JDK动态代理接口和接口实现类深入详解

 
/**
 * 要代理的接口
 */
public interface Target{
    String say();
}
/**
 * 真实调用对象
 */
public class RealTarget {
    public String invoke(){
        return "i'm proxy";
    }
}
/**
 * JDK代理类生成
 */
public class JDKProxy implements InvocationHandler {
    private Object target;
    JDKProxy(Object target) {
        this.target = target;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] paramValues) {
        System.out.println("Before method invocation");
        Object result = ((RealTarget)target).invoke();
        System.out.println("After method invocation");
        return result;
    }
}
/**
 * 测试例子
 */
public class TestProxy {
    public static void main(String[] args){
        // 构建代理器
        JDKProxy proxy = new JDKProxy(new RealTarget());
        ClassLoader classLoader = ClassLoaderUtils.getCurrentClassLoader();
        // 把生成的代理类保存到文件
        System.setProperty("sun.misc.ProxyGenerator.saveGeneratedFiles","true");
        // 生成代理类
        Target test = (Target) Proxy.newProxyInstance(classLoader, new Class[]{Target.class}, proxy);
        // 方法调用
        System.out.println(test.say());
    }
}

package com.sun.proxy;
import com.proxy.Hello;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
public final class $Proxy0 extends Proxy implements Target {
  private static Method m3;
  private static Method m1;
  private static Method m0;
  private static Method m2;
  public $Proxy0(InvocationHandler paramInvocationHandler) {
    super(paramInvocationHandler);
  }
  public final String say() {
    try {
      return (String)this.h.invoke(this, m3, null);
    } catch (Error|RuntimeException error) {
      throw null;
    } catch (Throwable throwable) {
      throw new UndeclaredThrowableException(throwable);
    } 
  }
  public final boolean equals(Object paramObject) {
    try {
      return ((Boolean)this.h.invoke(this, m1, new Object[] { paramObject })).booleanValue();
    } catch (Error|RuntimeException error) {
      throw null;
    } catch (Throwable throwable) {
      throw new UndeclaredThrowableException(throwable);
    } 
  }
  public final int hashCode() {
    try {
      return ((Integer)this.h.invoke(this, m0, null)).intValue();
    } catch (Error|RuntimeException error) {
      throw null;
    } catch (Throwable throwable) {
      throw new UndeclaredThrowableException(throwable);
    } 
  }
  public final String toString() {
    try {
      return (String)this.h.invoke(this, m2, null);
    } catch (Error|RuntimeException error) {
      throw null;
    } catch (Throwable throwable) {
      throw new UndeclaredThrowableException(throwable);
    } 
  }
  static {
    try {
      m3 = Class.forName("com.proxy.Target").getMethod("say", new Class[0]);
      m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[] { Class.forName("java.lang.Object") });
      m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
      m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
      return;
    } catch (NoSuchMethodException noSuchMethodException) {
      throw new NoSuchMethodError(noSuchMethodException.getMessage());
    } catch (ClassNotFoundException classNotFoundException) {
      throw new NoClassDefFoundError(classNotFoundException.getMessage());
    } 
  }
}