1    package classUtils.delegate; 
2     
3     
4    public class Delegator { 
5     
6        // preloaded Method objects for the methods in java.lang.Object 
7        private static java.lang.reflect.Method hashCodeMethod; 
8        private static java.lang.reflect.Method equalsMethod; 
9        private static java.lang.reflect.Method toStringMethod; 
10    
11       static { 
12           try { 
13               hashCodeMethod = Object.class.getMethod("hashCode", null); 
14               equalsMethod = 
15                       Object.class.getMethod("equals", new Class[]{Object.class 
16                       }); 
17               toStringMethod = Object.class.getMethod("toString", null); 
18           } catch (NoSuchMethodException e) { 
19               throw new NoSuchMethodError(e.getMessage()); 
20           } 
21       } 
22    
23    
24       private Class[] interfaces; 
25       private Object[] delegates; 
26    
27       public Delegator(Class[] interfaces, Object[] delegates) { 
28           this.interfaces = (Class[]) interfaces.clone(); 
29           this.delegates = (Object[]) delegates.clone(); 
30       } 
31    
32       public Object invoke(Object proxy, java.lang.reflect.Method m, Object[] args) 
33               throws Throwable { 
34           Class declaringClass = m.getDeclaringClass(); 
35    
36           if (declaringClass == Object.class) { 
37               if (m.equals(hashCodeMethod)) { 
38                   return proxyHashCode(proxy); 
39               } else if (m.equals(equalsMethod)) { 
40                   return proxyEquals(proxy, args[0]); 
41               } else if (m.equals(toStringMethod)) { 
42                   return proxyToString(proxy); 
43               } else { 
44                   throw new InternalError( 
45                           "unexpected Object method dispatched: " + m); 
46               } 
47           } else { 
48               for (int i = 0; i < interfaces.length; i++) { 
49                   if (declaringClass.isAssignableFrom(interfaces[i])) { 
50                       try { 
51                           return m.invoke(delegates[i], args); 
52                       } catch (java.lang.reflect.InvocationTargetException e) { 
53                           throw e.getTargetException(); 
54                       } 
55                   } 
56               } 
57    
58               return invokeNotDelegated(proxy, m, args); 
59           } 
60       } 
61    
62       protected Object invokeNotDelegated(Object proxy, java.lang.reflect.Method m, 
63                                           Object[] args) 
64               throws Throwable { 
65           throw new InternalError("unexpected method dispatched: " + m); 
66       } 
67    
68       protected Integer proxyHashCode(Object proxy) { 
69           return new Integer(System.identityHashCode(proxy)); 
70       } 
71    
72       protected Boolean proxyEquals(Object proxy, Object other) { 
73           return (proxy == other ? Boolean.TRUE : Boolean.FALSE); 
74       } 
75    
76       protected String proxyToString(Object proxy) { 
77           return proxy.getClass().getName() + '@' + 
78                   Integer.toHexString(proxy.hashCode()); 
79       } 
80   }