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1
4 package com.tc.util;
5
6 import org.apache.commons.lang.exception.ExceptionUtils;
7
8 import java.io.IOException  ;
9 import java.io.Writer ;
10 import java.lang.reflect.InvocationHandler ;
11 import java.lang.reflect.InvocationTargetException ;
12 import java.lang.reflect.Method ;
13 import java.lang.reflect.Proxy ;
14 import java.util.ArrayList ;
15 import java.util.List ;
16
17
26 public class LoggingInvocationHandler implements InvocationHandler {
27
28 private final Object delegate;
29 private final Writer dest;
30 private final Class [] furtherProxies;
31
32 public LoggingInvocationHandler(Object delegate, Writer dest, Class [] furtherProxies) {
33 Assert.assertNotNull(delegate);
34 Assert.assertNotNull(dest);
35 Assert.assertNoNullElements(furtherProxies);
36 this.delegate = delegate;
37 this.dest = dest;
38 this.furtherProxies = furtherProxies;
39 }
40
41 public Object invoke(Object arg0, Method arg1, Object [] arg2) throws Throwable {
42 Thread theThread = Thread.currentThread();
43 StringBuffer message = new StringBuffer ();
44
45 message.append("[" + theThread.getName() + "]: " + delegate + "." + arg1 + "(" + describeArguments(arg2) + ")");
46 try {
47 Object result = arg1.invoke(delegate, arg2);
48 message.append(" ==> " + result);
49 process(message.toString());
50 return reproxify(result);
51 } catch (InvocationTargetException ite) {
52 message.append(" => THROWABLE: ");
53 message.append(ExceptionUtils.getStackTrace(ite.getCause()));
54 message.append(".");
55 process(message.toString());
56 throw ite.getCause();
57 }
58 }
59
60 private Object reproxify(Object out) {
61 if (out == null) return out;
62 if (Proxy.isProxyClass(out.getClass())) return out;
63
64 List implementedClasses = new ArrayList ();
65
66 for (int i = 0; i < furtherProxies.length; ++i) {
67 if (furtherProxies[i].isInstance(out)) {
68 implementedClasses.add(furtherProxies[i]);
69 }
70 }
71
72 if (implementedClasses.size() > 0) {
73 return Proxy.newProxyInstance(getClass().getClassLoader(), (Class []) implementedClasses
74 .toArray(new Class [implementedClasses.size()]), new LoggingInvocationHandler(out, this.dest,
75 this.furtherProxies));
76 } else {
77 return out;
78 }
79 }
80
81 private String describeArguments(Object [] arguments) {
82 if (arguments == null) return "";
83
84 StringBuffer out = new StringBuffer ();
85
86 for (int i = 0; i < arguments.length; ++i) {
87 if (i > 0) out.append(", ");
88 out.append(arguments[i]);
89 }
90
91 return out.toString();
92 }
93
94 private void process(String message) {
95 try {
96 dest.write("\n\n" + message + "\n");
97 dest.flush();
98 } catch (IOException ioe) {
99 throw Assert.failure("Got an IOException when writing.", ioe);
100 }
101 }
102
103 }
104 |
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