Java中反射及动态编译

package tk.javazhangwei.testReflection;

public class Users {
private int id;
private int age;
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Users(int id, int age, String name) {
super();
this.id = id;
this.age = age;
this.name = name;
}
public Users() {
// TODO Auto-generated constructor stub
}
}

package tk.javazhangwei.testReflection;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/***
* 通过反射动态的api，操作构造器 方法 属性
* @author zw
*
*/
public class Demo02 {

public static void main(String[] args) throws InstantiationException, IllegalAccessException, NoSuchMethodException, SecurityException, IllegalArgumentException, InvocationTargetException, NoSuchFieldException {
String path ="tk.javazhangwei.testReflection.Users";
try {
Class<Users> clazz = (Class<Users>)Class.forName(path);
Users u = clazz.newInstance();

Constructor<Users>  u1= clazz.getDeclaredConstructor(int.class,int.class,String.class);
Users u2 = u1.newInstance(1001,18,"张伟");
System.out.println(u2.getName());

//通过反射Api，调用普通方法
Users u3 = clazz.newInstance();
//u3.setName("老宋");
Method method = clazz.getDeclaredMethod("setName", String.class);
method.invoke(u3, "老王");//相当于u3.setName();
System.out.println(u3.getName());

//通过反射操作属性
Users u4 = clazz.newInstance();
Field f = clazz.getDeclaredField("name");
f.setAccessible(true);//这个属性不需要做安全检查了  直接访问
f.set(u4, "老宋");//通过反射写属性
System.out.println(u4.getName());
System.out.println(f.get(u4));

} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}

}

package tk.javazhangwei.testDynamicCompile;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;
/***
* 动态编译java 并且运行
* @author zw
*
*/

public class Demo01 {

public static void main(String[] args) throws IOException, ClassNotFoundException, NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {

String msg ="public class msg{public static void main(String[] args){System.out.println(\"nishizhu\");}}";
File f = new File("d:/mycode/test/msg.java");
OutputStream os = new FileOutputStream(f);
byte[] data = msg.getBytes();
os.write(data, 0, data.length);
os.flush();
System.out.println("写入文件成功~");
os.close();

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
int result = compiler.run(null, null, null, "d:/mycode/test/msg.java");
System.out.println(result==0?"编译成功":"编译失败 ");

//常规方法
/*Runtime run =Runtime.getRuntime();
Process process =run.exec("java -cp d:/mycode/test/ msg");
InputStream is = process.getInputStream();
BufferedReader bw = new BufferedReader(new InputStreamReader(is));
String info = "";
while((info=bw.readLine())!=null) {
System.out.println("编译结果"+info);
}
is.close();*/
//
URL[] urls = new URL[] {new URL("file:/"+"d:/mycode/test/")};
URLClassLoader loader = new URLClassLoader(urls);
Class c =loader.loadClass("msg");
Method m =c.getMethod("main", String[].class);
m.invoke(null, (Object)new String[] {});
}

}