ExceptionHelperImpl


1   /*
2    * All content copyright (c) 2003-2006 Terracotta, Inc., except as may otherwise be noted in a separate copyright notice.  All rights reserved.
3    */
4   package com.tc.exception;
5   
6   import java.util.Iterator  ;
7   import java.util.LinkedList  ;
8   import java.util.List  ;
9   
10  /**
11   * Helper for extracting proximate cause and ultimate cause from exceptions.
12   */
13  public class ExceptionHelperImpl implements ExceptionHelper {
14    
15    private final List   helpers = new LinkedList  ();
16    private final ExceptionHelper nullHelper = new NullExceptionHelper();
17    
18    public boolean accepts(Throwable   t) {
19      return true;
20    }
21    
22    public void addHelper(ExceptionHelper helper) {
23      helpers.add(helper);
24    }
25  
26    public Throwable   getProximateCause(Throwable   t) {
27      return getHelperFor(t).getProximateCause(t);
28    }
29  
30    public Throwable   getUltimateCause(Throwable   t) {
31      Throwable   rv = getProximateCause(t);
32      while (rv != getProximateCause(rv)) {
33        rv = getProximateCause(rv);
34      }
35      return rv;
36      //return getHelperFor(t).getUltimateCause(t);
37    }
38    
39    private ExceptionHelper getHelperFor(Throwable   t) {
40      ExceptionHelper helper;
41      for (Iterator   i = helpers.iterator(); i.hasNext(); ) {
42        helper = (ExceptionHelper) i.next();
43        if (helper.accepts(t)) return helper;
44      }
45      return nullHelper;
46    }
47    
48    private static final class NullExceptionHelper implements ExceptionHelper{
49  
50      public boolean accepts(Throwable   t) {
51        return true;
52      }
53      
54      public Throwable   getProximateCause(Throwable   t) {
55        return t;
56      }
57  
58      public Throwable   getUltimateCause(Throwable   t) {
59        return t;
60      }
61      
62    }
63  
64  }
65
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags