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1   /*
2    * $Id: AbstractExceptionHandler.java 471754 2006-11-06 14:55:09Z husted $
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  package org.apache.struts.chain.commands;
22  
23  import org.apache.commons.logging.Log;
24  import org.apache.commons.logging.LogFactory;
25  import org.apache.struts.chain.contexts.ActionContext;
26  import org.apache.struts.config.ActionConfig;
27  import org.apache.struts.config.ExceptionConfig;
28  import org.apache.struts.config.ForwardConfig;
29  import org.apache.struts.config.ModuleConfig;
30  
31  /**
32   * <p>Invoke the local or global exception handler configured for the
33   * exception class that occurred.</p>
34   *
35   * @version $Rev: 471754 $ $Date: 2005-11-12 13:01:44 -0500 (Sat, 12 Nov 2005)
36   *          $
37   */
38  public abstract class AbstractExceptionHandler extends ActionCommandBase {
39      // ------------------------------------------------------ Instance Variables
40  
41      /**
42       * Provide a Commons logging instance for this class.
43       */
44      private static final Log LOG =
45          LogFactory.getLog(AbstractExceptionHandler.class);
46  
47      // ---------------------------------------------------------- Public Methods
48  
49      /**
50       * <p>Invoke the appropriate <code>Action</code> for this request, and
51       * cache the returned <code>ActionForward</code>.</p>
52       *
53       * @param actionCtx The <code>Context</code> for the current request
54       * @return <code>false</code> if a <code>ForwardConfig</code> is returned,
55       *         else <code>true</code> to complete processing
56       * @throws Exception if thrown by the Action class and not declared by an
57       *                   Exception Handler
58       */
59      public boolean execute(ActionContext actionCtx)
60          throws Exception {
61          // Look up the exception that was thrown
62          Exception exception = actionCtx.getException();
63  
64          if (exception == null) {
65              LOG.warn("No Exception found in ActionContext");
66  
67              return (true);
68          }
69  
70          // Look up the local or global exception handler configuration
71          ExceptionConfig exceptionConfig = null;
72          ActionConfig actionConfig = actionCtx.getActionConfig();
73          ModuleConfig moduleConfig = actionCtx.getModuleConfig();
74  
75          if (actionConfig != null) {
76              if (LOG.isDebugEnabled()) {
77                  LOG.debug("See if actionConfig " + actionConfig
78                      + " has an exceptionConfig for "
79                      + exception.getClass().getName());
80              }
81  
82              exceptionConfig = actionConfig.findException(exception.getClass());
83          } else if (moduleConfig != null) {
84              if (LOG.isDebugEnabled()) {
85                  LOG.debug("No action yet, see if moduleConfig " + moduleConfig
86                      + " has an exceptionConfig "
87                      + exception.getClass().getName());
88              }
89  
90              exceptionConfig = moduleConfig.findException(exception.getClass());
91          }
92  
93          // Handle the exception in the configured manner
94          if (exceptionConfig == null) {
95              LOG.warn("Unhandled exception", exception);
96              throw exception;
97          }
98  
99          ForwardConfig forwardConfig =
100             handle(actionCtx, exception, exceptionConfig, actionConfig,
101                 moduleConfig);
102 
103         if (forwardConfig != null) {
104             actionCtx.setForwardConfig(forwardConfig);
105 
106             return (false);
107         } else {
108             return (true);
109         }
110     }
111 
112     // ------------------------------------------------------- Protected Methods
113 
114     /**
115      * <p>Perform the required handling of the specified exception.</p>
116      *
117      * @param context         The <code>Context</code> for this request
118      * @param exception       The exception being handled
119      * @param exceptionConfig The corresponding {@link ExceptionConfig}
120      * @param actionConfig    The {@link ActionConfig} for this request
121      * @param moduleConfig    The {@link ModuleConfig} for this request
122      * @return the <code>ForwardConfig</code> to be processed next (if any),
123      *         or <code>null</code> if processing has been completed
124      * @throws Exception if there are any problems handling the exception
125      */
126     protected abstract ForwardConfig handle(ActionContext context,
127         Exception exception, ExceptionConfig exceptionConfig,
128         ActionConfig actionConfig, ModuleConfig moduleConfig)
129         throws Exception;
130 }