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1   /*
2    * Copyright 2002,2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.commons.jelly.tags.core;
17  
18  import org.apache.commons.jelly.JellyTagException;
19  import org.apache.commons.jelly.TagSupport;
20  import org.apache.commons.jelly.XMLOutput;
21  
22  /***
23   * A tag which catches exceptions thrown by its body.
24   * This allows conditional logic to be performed based on if exceptions
25   * are thrown or to do some kind of custom exception logging logic.
26   *
27   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
28   * @version $Revision: 155420 $
29   */
30  public class CatchTag extends TagSupport {
31  
32      private String var;
33  
34      public CatchTag() {
35      }
36  
37      // Tag interface
38      //-------------------------------------------------------------------------
39      public void doTag(XMLOutput output) throws JellyTagException {
40          if (var != null) {
41              context.removeVariable(var);
42          }
43          try {
44              invokeBody(output);
45          }
46          catch (Throwable t) {
47              if (var != null) {
48                  context.setVariable(var, t);
49              }
50          }
51      }
52  
53      // Properties
54      //-------------------------------------------------------------------------
55  
56      /***
57       * Sets the name of the variable which is exposed with the Exception that gets
58       * thrown by evaluating the body of this tag or which is set to null if there is
59       * no exception thrown.
60       */
61      public void setVar(String var) {
62          this.var = var;
63      }
64  }