jdk动态代理(Proxy,InvocationHandler),含$Proxy0源码
一.相关类及其方法:

java.lang.reflect.Proxy,
Proxy 提供用于创建动态代理类和实例的静态方法.
newProxyInstance()
返回一个指定接口的代理类实例，该接口可以将方法调用指派到指定的调用处理程序
(详见api文档)

java.lang.reflect.InvocationHandler,
InvocationHandler 是代理实例的调用处理程序 实现的接口。
invoke()
在代理实例上处理方法调用并返回结果。在与方法关联的代理实例上调用方法时，将在调用处理程序上调用此方法。
(详见api文档)

二.源代码:

被代理对象的接口及实现类:
Java代码 收藏代码

 1. class Proxy{     2.    InvocationHandler h=null;     3.    protected Proxy(InvocationHandler h) {     4.     this.h = h;     5.    }     6.    ...     7. }  class Proxy{   InvocationHandler h=null;   protected Proxy(InvocationHandler h) {    this.h = h;   }   ...}

下面是本例的$Proxy0类的源码(好不容易才把它提出来,改了JRE源码,打印出字节码,把字节码保存为class文件,并反编译class文件):


Java代码 收藏代码

1. import java.lang.reflect.InvocationHandler;
2. import java.lang.reflect.Method;
3. import java.lang.reflect.Proxy;
4. import java.lang.reflect.UndeclaredThrowableException;
5.
6. public final class $Proxy0 extends Proxy implements Manager {
7.
8. private static Method m1;
9. private static Method m0;
10. private static Method m3;
11. private static Method m2;
12.
13. static {
14. try {
15. m1 = Class.forName("java.lang.Object").getMethod("equals",
16. new Class[] { Class.forName("java.lang.Object") });
17. m0 = Class.forName("java.lang.Object").getMethod("hashCode",
18. new Class[0]);
19. m3 = Class.forName("com.ml.test.Manager").getMethod("modify",
20. new Class[0]);
21. m2 = Class.forName("java.lang.Object").getMethod("toString",
22. new Class[0]);
23. } catch (NoSuchMethodException nosuchmethodexception) {
24. throw new NoSuchMethodError(nosuchmethodexception.getMessage());
25. } catch (ClassNotFoundException classnotfoundexception) {
26. throw new NoClassDefFoundError(classnotfoundexception.getMessage());
27. }
28. }
29.
30. public $Proxy0(InvocationHandler invocationhandler) {
31. super(invocationhandler);
32. }
33.
34. @Override
35. public final boolean equals(Object obj) {
36. try {
37. return ((Boolean) super.h.invoke(this, m1, new Object[] { obj }))
38. .booleanValue();
39. } catch (Throwable throwable) {
40. throw new UndeclaredThrowableException(throwable);
41. }
42. }
43.
44. @Override
45. public final int hashCode() {
46. try {
47. return ((Integer) super.h.invoke(this, m0, null)).intValue();
48. } catch (Throwable throwable) {
49. throw new UndeclaredThrowableException(throwable);
50. }
51. }
52.
53. public final void modify() {
54. try {
55. super.h.invoke(this, m3, null);
56. return;
57. } catch (Error e) {
58. } catch (Throwable throwable) {
59. throw new UndeclaredThrowableException(throwable);
60. }
61. }
62.
63. @Override
64. public final String toString() {
65. try {
66. return (String) super.h.invoke(this, m2, null);
67. } catch (Throwable throwable) {
68. throw new UndeclaredThrowableException(throwable);
69. }
70. }
71. }

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 Manager {

private static Method m1;
private static Method m0;
private static Method m3;
private static Method m2;

static {
try {
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]);
m3 = Class.forName("com.ml.test.Manager").getMethod("modify",
new Class[0]);
m2 = Class.forName("java.lang.Object").getMethod("toString",
new Class[0]);
} catch (NoSuchMethodException nosuchmethodexception) {
throw new NoSuchMethodError(nosuchmethodexception.getMessage());
} catch (ClassNotFoundException classnotfoundexception) {
throw new NoClassDefFoundError(classnotfoundexception.getMessage());
}
}

public $Proxy0(InvocationHandler invocationhandler) {
super(invocationhandler);
}

@Override
public final boolean equals(Object obj) {
try {
return ((Boolean) super.h.invoke(this, m1, new Object[] { obj }))
.booleanValue();
} catch (Throwable throwable) {
throw new UndeclaredThrowableException(throwable);
}
}

@Override
public final int hashCode() {
try {
return ((Integer) super.h.invoke(this, m0, null)).intValue();
} catch (Throwable throwable) {
throw new UndeclaredThrowableException(throwable);
}
}

public final void modify() {
try {
super.h.invoke(this, m3, null);
return;
} catch (Error e) {
} catch (Throwable throwable) {
throw new UndeclaredThrowableException(throwable);
}
}

@Override
public final String toString() {
try {
return (String) super.h.invoke(this, m2, null);
} catch (Throwable throwable) {
throw new UndeclaredThrowableException(throwable);
}
}
}


接着把得到的$Proxy0实例强制转换成Manager.
当执行managerProxy.modify()方法时,就调用了$Proxy0类中的modify()方法.
在modify方法中,调用父类Proxy中的h的invoke()方法.
即InvocationHandler.invoke();