深入理解Sping——AOP的试水

深入理解Sping——AOP的试水

定义接口

public interface HelloWorld {
void printHelloWorld();

void doPrint();
}

定义接口的实现

public class HelloWorldImpl1 implements HelloWorld {

public void printHelloWorld() {
System.out.println("Enter HelloWorldImpl1.printHelloWorld()");
}

public void doPrint() {
System.out.println("Enter HelloWorldImpl1.doPrint()");
return;
}
}

public class HelloWorldImpl2 implements HelloWorld {

public void printHelloWorld() {
System.out.println("Enter HelloWorldImpl2.printHelloWorld()");
}

public void doPrint() {
System.out.println("Enter HelloWorldImpl2.doPrint()");
return;
}
}

定义Handler

public class LogHandler {

public void LogBefore() {
System.out.println("Log before method");
}

public void LogAfter() {
System.out.println("Log after method");
}
}

public class TimeHandler {

public void printTime() {
System.out.println("CurrentTime = " + System.currentTimeMillis());
}
}

定义XML配置

//spring-context-aop.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd"> 
<bean id="helloWorldImpl1" class="com.melon.spring.aop.helloworld.HelloWorldImpl1"/>
<bean id="helloWorldImpl2" class="com.melon.spring.aop.helloworld.HelloWorldImpl2"/>
<bean id="timeHandler" class="com.melon.spring.aop.helloworld.TimeHandler"/>
<bean id="logHandler" class="com.melon.spring.aop.helloworld.LogHandler"/>

<!--proxy-target-class 为true，基于类代理；为false，基于接口代理-->
<aop:config>
<!--
（1）aspect里面有一个order属性，order属性的数字就是横切关注点的顺序
（2）把logHandler定义在timeHandler前面，Spring默认以aspect的定义顺序作为织入顺序
-->
<aop:aspect id="time" ref="timeHandler">
<aop:pointcut id="addAllMethod" expression="execution(* com.melon.spring.aop.helloworld.HelloWorld.*(..))"/>
<aop:before method="printTime" pointcut-ref="addAllMethod"/>
<aop:after method="printTime" pointcut-ref="addAllMethod"/>
</aop:aspect>
<aop:aspect id="log" ref="logHandler" order="2">
<aop:pointcut id="printLog" expression="execution(* com.melon.spring.aop.helloworld.HelloWorld.*(..))"/>
<aop:before method="LogBefore" pointcut-ref="printLog"/>
<aop:after method="LogAfter" pointcut-ref="printLog"/>
</aop:aspect>
</aop:config>
</beans>

定义测试类

@Log4j2
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring/spring-context-test.xml"})
@WebAppConfiguration
public class AopTest {
@Test
public void testHelloWorld() {

HelloWorld hw1 = (HelloWorld) SpringContextHolder.getBean("helloWorldImpl1");
HelloWorld hw2 = (HelloWorld) SpringContextHolder.getBean("helloWorldImpl2");
hw1.printHelloWorld();
System.out.println();
hw1.doPrint();

System.out.println();
hw2.printHelloWorld();
System.out.println();
hw2.doPrint();
}
}

Log before method
CurrentTime = 1485690199071
Enter HelloWorldImpl1.printHelloWorld()
CurrentTime = 1485690199079
Log after method

Log before method
CurrentTime = 1485690199079
Enter HelloWorldImpl1.doPrint()
CurrentTime = 1485690199079
Log after method

Log before method
CurrentTime = 1485690199079
Enter HelloWorldImpl2.printHelloWorld()
CurrentTime = 1485690199085
Log after method

Log before method
CurrentTime = 1485690199085
Enter HelloWorldImpl2.doPrint()
CurrentTime = 1485690199085
Log after method