1. package cn.itcast.day3;
   
2. 
   
3. import java.lang.reflect.Constructor;
   
4. import java.lang.reflect.InvocationHandler;
   
5. import java.lang.reflect.Method;
   
6. import java.lang.reflect.Proxy;
   
7. import java.util.Collection;
   
8. 
   
9. public class ProxyTest {
   
10. 
    
11. /**
    
12. * @param args
    
13. */
    
14. public static void main(String[] args)throws Exception {
    
15. // TODO Auto-generated method stub
    
16. 
    
17. Class clazzProxy1 = Proxy.getProxyClass(Collection.class.getClassLoader(), Collection.class);
    
18. System.out.println(clazzProxy1.getName());
    
19. 
    
20. System.out.println("------begin constructors list------");
    
21. /*$Proxy0()
    
22. $Proxy0(InvocationHandler,int)*/
    
23. Constructor[] constructors = clazzProxy1.getConstructors();
    
24. for(Constructor constructor : constructors){
    
25. String name = constructor.getName();
    
26. StringBuilder sBuilder = new StringBuilder(name);
    
27. sBuilder.append('(');
    
28. Class[] clazzParams = constructor.getParameterTypes();
    
29. for(Class clazzParam : clazzParams){
    
30. sBuilder.append(clazzParam.getName()).append(',');
    
31. }
    
32. if(clazzParams!=null && clazzParams.length != 0)
    
33. sBuilder.deleteCharAt(sBuilder.length()-1);
    
34. sBuilder.append(')');
    
35. 
    
36. System.out.println(sBuilder.toString());
    
37. }
    
38. 
    
39. 
    
40. 
    
41. 
    
42. System.out.println("------begin methods list------");
    
43. /*$Proxy0()
    
44. $Proxy0(InvocationHandler,int)*/
    
45. Method[] methods = clazzProxy1.getMethods();
    
46. for(Method method : methods){
    
47. String name = method.getName();
    
48. StringBuilder sBuilder = new StringBuilder(name);
    
49. sBuilder.append('(');
    
50. Class[] clazzParams = method.getParameterTypes();
    
51. for(Class clazzParam : clazzParams){
    
52. sBuilder.append(clazzParam.getName()).append(',');
    
53. }
    
54. if(clazzParams!=null && clazzParams.length != 0)
    
55. sBuilder.deleteCharAt(sBuilder.length()-1);
    
56. sBuilder.append(')');
    
57. 
    
58. System.out.println(sBuilder.toString());
    
59. }
    
60. System.out.println("------begin create instance object------");
    
61. //Object obj = clazzProxy1.newInstance();
    
62. Constructor constructor = clazzProxy1.getConstructor(InvocationHandler.class);
    
63. class MyInvocationHandler1 implements InvocationHandler {
    
64. 
    
65. @Override
    
66. public Object invoke(Object proxy, Method method, Object[] args)
    
67. throws Throwable {
    
68. // TODO Auto-generated method stub
    
69. return null;
    
70. }
    
71. Collection proxy1 = (Collection)constructor.newInstance(new MyInvocationHandler1());//
    
72. 
    
73. System.out.println(proxy1);
    
74. 
    
75. 
    
76. }
    
77. }
    
78. 
    
79. }
    

复制代码

最后一行打印代码System.out.println(proxy1);为什么不能打印？求解答。。。。。。

缩进一下
Collection proxy1 = (Collection)constructor.newInstance(new MyInvocationHandler1());//
System.out.println(proxy1);
这2句直接写在了ProxyTest类里面，放进main函数里面

打印出来的结果是null，但对象是创建成功了
只是还没有补全invoke方法，所以这个对象的toString方法返回了null

温少邦 发表于 2012-7-12 08:01
缩进一下
Collection proxy1 = (Collection)constructor.newInstance(new MyInvocationHandler1());//
Syst ...

:handshake,谢谢！