反射实现 AOP 动态代理模式(Spring AOP 的实现 原理)
2014-01-16 10:42
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其实AOP的意思就是面向切面编程.
OO注重的是我们解决问题的方法(封装成Method),而AOP注重的是许多解决解决问题的方法中的共同点,是对OO思想的一种补充!
还是拿人家经常举的一个例子讲解一下吧:
比如说,我们现在要开发的一个应用里面有很多的业务方法,但是,我们现在要对这个方法的执行做全面监控,或部分监控.也许我们就会在要一些方法前去加上一条日志记录,
我们写个例子看看我们最简单的解决方案
我们先写一个接口IHello.java代码如下:
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public interface IHello {
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 假设这是一个业务方法
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param name
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void sayHello(String name);
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
里面有个方法,用于输入"Hello" 加传进来的姓名;我们去写个类实现IHello接口
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Hello implements IHello {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayHello(String name) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println("Hello " + name);
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
现在我们要为这个业务方法加上日志记录的业务,我们在不改变原代码的情况下,我们会去怎么做呢?也许,你会去写一个类去实现IHello接口,并依赖Hello这个类.代码如下:
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class HelloProxy implements IHello {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private IHello hello;
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public HelloProxy(IHello hello) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
1db15
this.hello = hello;
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayHello(String name) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.DEBUGE, "sayHello method start
![](http://www.blogjava.net/Images/dot.gif)
.");
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello(name);
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, "sayHello method end!");
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
15
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
其中.Logger类和Level枚举代码如下:
Logger.java
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.util.Date;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Logger{
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 根据等级记录日志
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param level
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param context
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void logging(Level level, String context) {
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
if (level.equals(Level.INFO)) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println(new Date().toLocaleString() + " " + context);
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
if (level.equals(Level.DEBUGE)) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.err.println(new Date() + " " + context);
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Level.java
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public enum Level {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
INFO,DEBUGE;
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
那我们去写个测试类看看,代码如下:
Test.java
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = new HelloProxy(new Hello());
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Doublej");
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
运行以上代码我们可以得到下面结果:
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Tue Mar 04 20:57:12 CST 2008 sayHello method start
![](http://www.blogjava.net/Images/dot.gif)
.
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Hello Doublej
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
2008-3-4 20:57:12 sayHello method end!
从上面的代码我们可以看出,hello对象是被HelloProxy这个所谓的代理态所创建的.这样,如果我们以后要把日志记录的功能去掉.那我们只要把得到hello对象的代码改成以下:
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = new Hello();
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Doublej");
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
8
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
9
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
上面代码,可以说是AOP最简单的实现!
但是我们会发现一个问题,如果我们像Hello这样的类很多,那么,我们是不是要去写很多个HelloProxy这样的类呢.没错,是的.其实也是一种很麻烦的事.在jdk1.3以后.jdk跟我们提供了一个API java.lang.reflect.InvocationHandler的类.
这个类可以让我们在JVM调用某个类的方法时动态的为些方法做些什么事.让我们把以上的代码改一下来看看效果.
同样,我们写一个IHello的接口和一个Hello的实现类.在接口中.我们定义两个方法;代码如下 :
IHello.java
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public interface IHello {
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 业务处理A方法
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param name
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void sayHello(String name);
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 业务处理B方法
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param name
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void sayGoogBye(String name);
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Hello.java
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Hello implements IHello {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayHello(String name) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println("Hello " + name);
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayGoogBye(String name) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println(name+" GoodBye!");
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
我们一样的去写一个代理类.只不过.让这个类去实现java.lang.reflect.InvocationHandler接口,代码如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.InvocationHandler;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Proxy;
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![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class DynaProxyHello implements InvocationHandler {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象(也就是我们要在方法的前后加上业务逻辑的对象,如例子中的Hello)
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private Object delegate;
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 动态生成方法被处理过后的对象 (写法固定)
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
*
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param delegate
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param proxy
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @return
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public Object bind(Object delegate) {
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate = delegate;
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return Proxy.newProxyInstance(
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate.getClass().getClassLoader(), this.delegate
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
.getClass().getInterfaces(), this);
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象中的每个方法会被此方法送去JVM调用,也就是说,要处理的对象的方法只能通过此方法调用
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 此方法是动态的,不是手动调用的
30
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
public Object invoke(Object proxy, Method method, Object[] args)
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
throws Throwable {
33
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Object result = null;
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![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
try {
35
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//执行原来的方法之前记录日志
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.DEBUGE, method.getName() + " Method end
![](http://www.blogjava.net/Images/dot.gif)
.");
37
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//JVM通过这条语句执行原来的方法(反射机制)
39
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
result = method.invoke(this.delegate, args);
40
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//执行原来的方法之后记录日志
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, method.getName() + " Method Start!");
42
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
} catch (Exception e) {
43
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
e.printStackTrace();
44
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
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![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//返回方法返回值给调用者
46
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return result;
47
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
48
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
49
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
50
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
上面类中出现的Logger类和Level枚举还是和上一上例子的实现是一样的.这里就不贴出代码了.
让我们写一个Test类去测试一下.代码如下:
Test.java
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
4
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
5
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = (IHello)new DynaProxyHello().bind(new Hello());
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayGoogBye("Double J");
7
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Double J");
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
10
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
11
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
运行输出的结果如下:
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Tue Mar 04 21:24:03 CST 2008 sayGoogBye Method end
![](http://www.blogjava.net/Images/dot.gif)
.
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Double J GoodBye!
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
2008-3-4 21:24:03 sayGoogBye Method Start!
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Tue Mar 04 21:24:03 CST 2008 sayHello Method end
![](http://www.blogjava.net/Images/dot.gif)
.
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Hello Double J
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
2008-3-4 21:24:03 sayHello Method Start!
由于线程的关系,第二个方法的开始出现在第一个方法的结束之前.这不是我们所关注的!
从上面的例子我们看出.只要你是采用面向接口编程,那么,你的任何对象的方法执行之前要加上记录日志的操作都是可以的.他(DynaPoxyHello)自动去代理执行被代理对象(Hello)中的每一个方法,一个java.lang.reflect.InvocationHandler接口就把我们的代理对象和被代理对象解藕了.但是,我们又发现还有一个问题,这个DynaPoxyHello对象只能跟我们去在方法前后加上日志记录的操作.我们能不能把DynaPoxyHello对象和日志操作对象(Logger)解藕呢?
结果是肯定的.让我们来分析一下我们的需求.
我们要在被代理对象的方法前面或者后面去加上日志操作代码(或者是其它操作的代码),
那么,我们可以抽象出一个接口,这个接口里就只有两个方法,一个是在被代理对象要执行方法之前执行的方法,我们取名为start,第二个方法就是在被代理对象执行方法之后执行的方法,我们取名为end .接口定义如下 :
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
5
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public interface IOperation {
6
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
7
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 方法执行之前的操作
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param method
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
10
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void start(Method method);
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
12
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 方法执行之后的操作
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param method
14
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
15
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void end(Method method);
16
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
17
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
我们去写一个实现上面接口的类.我们把作他真正的操作者,如下面是日志操作者的一个类:
LoggerOperation.java
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class LoggerOperation implements IOperation {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void end(Method method) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.DEBUGE, method.getName() + " Method end
![](http://www.blogjava.net/Images/dot.gif)
.");
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void start(Method method) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, method.getName() + " Method Start!");
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
然后我们要改一下代理对象DynaProxyHello中的代码.如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.InvocationHandler;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
5
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Proxy;
6
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class DynaProxyHello implements InvocationHandler {
8
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
9
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 操作者
10
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
11
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private Object proxy;
12
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象(也就是我们要在方法的前后加上业务逻辑的对象,如例子中的Hello)
14
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
15
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private Object delegate;
16
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
17
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
18
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 动态生成方法被处理过后的对象 (写法固定)
19
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
*
20
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param delegate
21
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param proxy
22
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @return
23
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
24
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public Object bind(Object delegate,Object proxy) {
25
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
26
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.proxy = proxy;
27
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate = delegate;
28
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return Proxy.newProxyInstance(
29
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate.getClass().getClassLoader(), this.delegate
30
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
.getClass().getInterfaces(), this);
31
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
32
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
33
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象中的每个方法会被此方法送去JVM调用,也就是说,要处理的对象的方法只能通过此方法调用
34
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 此方法是动态的,不是手动调用的
35
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
36
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
public Object invoke(Object proxy, Method method, Object[] args)
37
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
throws Throwable {
38
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Object result = null;
39
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
try {
40
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//反射得到操作者的实例
41
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Class clazz = this.proxy.getClass();
42
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//反射得到操作者的Start方法
43
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Method start = clazz.getDeclaredMethod("start",
44
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
new Class[] { Method.class });
45
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//反射执行start方法
46
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
start.invoke(this.proxy, new Object[] { method });
47
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//执行要处理对象的原本方法
48
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
result = method.invoke(this.delegate, args);
49
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
// 反射得到操作者的end方法
50
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Method end = clazz.getDeclaredMethod("end",
51
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
new Class[] { Method.class });
52
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
// 反射执行end方法
53
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
end.invoke(this.proxy, new Object[] { method });
54
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
55
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
} catch (Exception e) {
56
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
e.printStackTrace();
57
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
58
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return result;
59
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
60
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
61
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
62
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
然后我们把Test.java中的代码改一下.测试一下:
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = (IHello)new DynaProxyHello().bind(new Hello(),new LoggerOperation());
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayGoogBye("Double J");
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Double J");
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
结果还是一样的吧.
如果你想在每个方法之前加上日志记录,而不在方法后加上日志记录.你就把LoggerOperation类改成如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
5
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class LoggerOperation implements IOperation {
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void end(Method method) {
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//Logger.logging(Level.DEBUGE, method.getName() + " Method end
![](http://www.blogjava.net/Images/dot.gif)
.");
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
10
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void start(Method method) {
12
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, method.getName() + " Method Start!");
13
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
14
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
15
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
16
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
运行一下.你就会发现,每个方法之后没有记录日志了. 这样,我们就把代理者和操作者解藕了!
下面留一个问题给大家,如果我们不想让所有方法都被日志记录,我们应该怎么去解藕呢.?
我的想法是在代理对象的public Object invoke(Object proxy, Method method, Object[] args)方法里面加上个if(),对传进来的method的名字进行判断,判断的条件存在XML里面.这样我们就可以配置文件时行解藕了.如果有兴趣的朋友可以把操作者,被代理者,都通过配置文件进行配置
,那么就可以写一个简单的SpringAOP框架了.
OO注重的是我们解决问题的方法(封装成Method),而AOP注重的是许多解决解决问题的方法中的共同点,是对OO思想的一种补充!
还是拿人家经常举的一个例子讲解一下吧:
比如说,我们现在要开发的一个应用里面有很多的业务方法,但是,我们现在要对这个方法的执行做全面监控,或部分监控.也许我们就会在要一些方法前去加上一条日志记录,
我们写个例子看看我们最简单的解决方案
我们先写一个接口IHello.java代码如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public interface IHello {
4
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
5
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 假设这是一个业务方法
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param name
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void sayHello(String name);
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
10
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
里面有个方法,用于输入"Hello" 加传进来的姓名;我们去写个类实现IHello接口
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Hello implements IHello {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayHello(String name) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println("Hello " + name);
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
现在我们要为这个业务方法加上日志记录的业务,我们在不改变原代码的情况下,我们会去怎么做呢?也许,你会去写一个类去实现IHello接口,并依赖Hello这个类.代码如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class HelloProxy implements IHello {
4
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private IHello hello;
5
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
6
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public HelloProxy(IHello hello) {
7
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
1db15
this.hello = hello;
8
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
9
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
10
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayHello(String name) {
11
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.DEBUGE, "sayHello method start
![](http://www.blogjava.net/Images/dot.gif)
.");
12
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello(name);
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, "sayHello method end!");
14
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
15
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
16
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
17
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
18
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
其中.Logger类和Level枚举代码如下:
Logger.java
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.util.Date;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
5
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Logger{
6
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
7
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 根据等级记录日志
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param level
9
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param context
10
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void logging(Level level, String context) {
12
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
if (level.equals(Level.INFO)) {
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println(new Date().toLocaleString() + " " + context);
14
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
15
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
if (level.equals(Level.DEBUGE)) {
16
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.err.println(new Date() + " " + context);
17
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
18
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
19
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
20
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
21
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Level.java
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public enum Level {
4
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
INFO,DEBUGE;
5
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
6
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
那我们去写个测试类看看,代码如下:
Test.java
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
4
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
5
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = new HelloProxy(new Hello());
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Doublej");
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
8
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
9
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
运行以上代码我们可以得到下面结果:
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Tue Mar 04 20:57:12 CST 2008 sayHello method start
![](http://www.blogjava.net/Images/dot.gif)
.
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Hello Doublej
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
2008-3-4 20:57:12 sayHello method end!
从上面的代码我们可以看出,hello对象是被HelloProxy这个所谓的代理态所创建的.这样,如果我们以后要把日志记录的功能去掉.那我们只要把得到hello对象的代码改成以下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.staticaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
4
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
5
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = new Hello();
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Doublej");
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
8
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
9
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
上面代码,可以说是AOP最简单的实现!
但是我们会发现一个问题,如果我们像Hello这样的类很多,那么,我们是不是要去写很多个HelloProxy这样的类呢.没错,是的.其实也是一种很麻烦的事.在jdk1.3以后.jdk跟我们提供了一个API java.lang.reflect.InvocationHandler的类.
这个类可以让我们在JVM调用某个类的方法时动态的为些方法做些什么事.让我们把以上的代码改一下来看看效果.
同样,我们写一个IHello的接口和一个Hello的实现类.在接口中.我们定义两个方法;代码如下 :
IHello.java
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public interface IHello {
4
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
5
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 业务处理A方法
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param name
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void sayHello(String name);
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
10
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 业务处理B方法
11
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param name
12
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void sayGoogBye(String name);
14
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
15
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Hello.java
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Hello implements IHello {
4
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
5
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayHello(String name) {
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println("Hello " + name);
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
8
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void sayGoogBye(String name) {
9
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
System.out.println(name+" GoodBye!");
10
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
12
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
我们一样的去写一个代理类.只不过.让这个类去实现java.lang.reflect.InvocationHandler接口,代码如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.InvocationHandler;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
5
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Proxy;
6
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class DynaProxyHello implements InvocationHandler {
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
10
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象(也就是我们要在方法的前后加上业务逻辑的对象,如例子中的Hello)
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
12
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private Object delegate;
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
14
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
15
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 动态生成方法被处理过后的对象 (写法固定)
16
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
*
17
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param delegate
18
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param proxy
19
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @return
20
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
21
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public Object bind(Object delegate) {
22
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate = delegate;
23
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return Proxy.newProxyInstance(
24
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate.getClass().getClassLoader(), this.delegate
25
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
.getClass().getInterfaces(), this);
26
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
27
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
28
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象中的每个方法会被此方法送去JVM调用,也就是说,要处理的对象的方法只能通过此方法调用
29
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 此方法是动态的,不是手动调用的
30
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
31
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
public Object invoke(Object proxy, Method method, Object[] args)
32
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
throws Throwable {
33
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Object result = null;
34
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
try {
35
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//执行原来的方法之前记录日志
36
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.DEBUGE, method.getName() + " Method end
![](http://www.blogjava.net/Images/dot.gif)
.");
37
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
38
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//JVM通过这条语句执行原来的方法(反射机制)
39
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
result = method.invoke(this.delegate, args);
40
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//执行原来的方法之后记录日志
41
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, method.getName() + " Method Start!");
42
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
} catch (Exception e) {
43
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
e.printStackTrace();
44
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
45
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//返回方法返回值给调用者
46
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return result;
47
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
48
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
49
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
50
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
上面类中出现的Logger类和Level枚举还是和上一上例子的实现是一样的.这里就不贴出代码了.
让我们写一个Test类去测试一下.代码如下:
Test.java
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
4
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
5
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = (IHello)new DynaProxyHello().bind(new Hello());
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayGoogBye("Double J");
7
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Double J");
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
10
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
11
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
运行输出的结果如下:
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Tue Mar 04 21:24:03 CST 2008 sayGoogBye Method end
![](http://www.blogjava.net/Images/dot.gif)
.
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Double J GoodBye!
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
2008-3-4 21:24:03 sayGoogBye Method Start!
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Tue Mar 04 21:24:03 CST 2008 sayHello Method end
![](http://www.blogjava.net/Images/dot.gif)
.
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
Hello Double J
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
2008-3-4 21:24:03 sayHello Method Start!
由于线程的关系,第二个方法的开始出现在第一个方法的结束之前.这不是我们所关注的!
从上面的例子我们看出.只要你是采用面向接口编程,那么,你的任何对象的方法执行之前要加上记录日志的操作都是可以的.他(DynaPoxyHello)自动去代理执行被代理对象(Hello)中的每一个方法,一个java.lang.reflect.InvocationHandler接口就把我们的代理对象和被代理对象解藕了.但是,我们又发现还有一个问题,这个DynaPoxyHello对象只能跟我们去在方法前后加上日志记录的操作.我们能不能把DynaPoxyHello对象和日志操作对象(Logger)解藕呢?
结果是肯定的.让我们来分析一下我们的需求.
我们要在被代理对象的方法前面或者后面去加上日志操作代码(或者是其它操作的代码),
那么,我们可以抽象出一个接口,这个接口里就只有两个方法,一个是在被代理对象要执行方法之前执行的方法,我们取名为start,第二个方法就是在被代理对象执行方法之后执行的方法,我们取名为end .接口定义如下 :
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
5
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public interface IOperation {
6
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
7
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 方法执行之前的操作
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param method
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
10
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void start(Method method);
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
12
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 方法执行之后的操作
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param method
14
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
15
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
void end(Method method);
16
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
17
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
我们去写一个实现上面接口的类.我们把作他真正的操作者,如下面是日志操作者的一个类:
LoggerOperation.java
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class LoggerOperation implements IOperation {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void end(Method method) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.DEBUGE, method.getName() + " Method end
![](http://www.blogjava.net/Images/dot.gif)
.");
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void start(Method method) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, method.getName() + " Method Start!");
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
然后我们要改一下代理对象DynaProxyHello中的代码.如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.InvocationHandler;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
5
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Proxy;
6
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class DynaProxyHello implements InvocationHandler {
8
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
9
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 操作者
10
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
11
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private Object proxy;
12
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
13
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象(也就是我们要在方法的前后加上业务逻辑的对象,如例子中的Hello)
14
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
15
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
private Object delegate;
16
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
17
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
18
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 动态生成方法被处理过后的对象 (写法固定)
19
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
*
20
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param delegate
21
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @param proxy
22
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* @return
23
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
24
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public Object bind(Object delegate,Object proxy) {
25
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
26
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.proxy = proxy;
27
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate = delegate;
28
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return Proxy.newProxyInstance(
29
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
this.delegate.getClass().getClassLoader(), this.delegate
30
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
.getClass().getInterfaces(), this);
31
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
32
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
/**
33
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 要处理的对象中的每个方法会被此方法送去JVM调用,也就是说,要处理的对象的方法只能通过此方法调用
34
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
* 此方法是动态的,不是手动调用的
35
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
*/
36
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
public Object invoke(Object proxy, Method method, Object[] args)
37
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
throws Throwable {
38
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Object result = null;
39
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
try {
40
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//反射得到操作者的实例
41
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Class clazz = this.proxy.getClass();
42
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//反射得到操作者的Start方法
43
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Method start = clazz.getDeclaredMethod("start",
44
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
new Class[] { Method.class });
45
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//反射执行start方法
46
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
start.invoke(this.proxy, new Object[] { method });
47
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//执行要处理对象的原本方法
48
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
result = method.invoke(this.delegate, args);
49
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
// 反射得到操作者的end方法
50
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Method end = clazz.getDeclaredMethod("end",
51
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
new Class[] { Method.class });
52
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
// 反射执行end方法
53
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
end.invoke(this.proxy, new Object[] { method });
54
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
55
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
} catch (Exception e) {
56
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
e.printStackTrace();
57
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
58
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
return result;
59
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
60
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
61
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
62
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
然后我们把Test.java中的代码改一下.测试一下:
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class Test {
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public static void main(String[] args) {
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
IHello hello = (IHello)new DynaProxyHello().bind(new Hello(),new LoggerOperation());
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayGoogBye("Double J");
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
hello.sayHello("Double J");
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
结果还是一样的吧.
如果你想在每个方法之前加上日志记录,而不在方法后加上日志记录.你就把LoggerOperation类改成如下:
1
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
package sinosoft.dj.aop.proxyaop;
2
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
3
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
import java.lang.reflect.Method;
4
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
5
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockStart.gif)
public class LoggerOperation implements IOperation {
6
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
7
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void end(Method method) {
8
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
//Logger.logging(Level.DEBUGE, method.getName() + " Method end
![](http://www.blogjava.net/Images/dot.gif)
.");
9
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
10
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
11
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
public void start(Method method) {
12
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
Logger.logging(Level.INFO, method.getName() + " Method Start!");
13
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
}
14
![](http://www.blogjava.net/Images/OutliningIndicators/InBlock.gif)
15
![](http://www.blogjava.net/Images/OutliningIndicators/ExpandedBlockEnd.gif)
}
16
![](http://www.blogjava.net/Images/OutliningIndicators/None.gif)
运行一下.你就会发现,每个方法之后没有记录日志了. 这样,我们就把代理者和操作者解藕了!
下面留一个问题给大家,如果我们不想让所有方法都被日志记录,我们应该怎么去解藕呢.?
我的想法是在代理对象的public Object invoke(Object proxy, Method method, Object[] args)方法里面加上个if(),对传进来的method的名字进行判断,判断的条件存在XML里面.这样我们就可以配置文件时行解藕了.如果有兴趣的朋友可以把操作者,被代理者,都通过配置文件进行配置
,那么就可以写一个简单的SpringAOP框架了.
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