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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 java.io.FileOutputStream;
19  import java.io.IOException;
20  import java.io.UnsupportedEncodingException;
21  
22  import org.apache.commons.jelly.JellyContext;
23  import org.apache.commons.jelly.JellyTagException;
24  import org.apache.commons.jelly.TagSupport;
25  import org.apache.commons.jelly.XMLOutput;
26  import org.apache.commons.logging.Log;
27  import org.apache.commons.logging.LogFactory;
28  
29  /*** A tag that spawns the contained script in a separate thread
30    *
31    * @author <a href="mailto:vinayc@apache.org">Vinay Chandran</a>
32    */
33  public class ThreadTag extends TagSupport  {
34      /*** Thread Name */
35      private String name = null;
36      /*** the destination of output */
37      private XMLOutput xmlOutput;
38      /*** Should we close the underlying output */
39      private boolean closeOutput;
40      /*** The Log to which logging calls will be made. */
41      private static final Log log = LogFactory.getLog(ThreadTag.class);
42  
43      public ThreadTag() {
44      }
45  
46      // Tag interface
47      //-------------------------------------------------------------------------
48      public void doTag(final XMLOutput output) throws JellyTagException {
49          if ( xmlOutput == null ) {
50              // lets default to system.out
51              try {
52                  xmlOutput = XMLOutput.createXMLOutput( System.out );
53              } catch (UnsupportedEncodingException e) {
54                  throw new JellyTagException(e);
55              }
56          }
57  
58          // lets create a child context
59          final JellyContext newContext = context.newJellyContext();
60  
61          Thread thread = new Thread(
62              new Runnable() {
63                  public void run() {
64                      try {
65                          getBody().run(newContext, xmlOutput);
66                          if (closeOutput) {
67                              xmlOutput.close();
68                          }
69                          else {
70                              xmlOutput.flush();
71                          }
72                      }
73                      catch (Exception e) {
74                          if (log.isErrorEnabled()) log.error("error running thread tag", e);
75                      }
76                  }
77              }
78          );
79          if ( name != null ) {
80              thread.setName( name );
81          }
82          thread.start();
83      }
84  
85      /***
86       * Sets the name of the thread.
87       * @param name The name to set
88       */
89      public void setName(String name) {
90          this.name = name;
91      }
92  
93      /***
94       * Sets the destination of output
95       */
96      public void setXmlOutput(XMLOutput xmlOutput) {
97          this.closeOutput = false;
98          this.xmlOutput = xmlOutput;
99      }
100 
101     /***
102      * Set the file which is generated from the output
103      * @param name The output file name
104      */
105     public void setFile(String name) throws IOException {
106         this.closeOutput = true;
107         setXmlOutput( XMLOutput.createXMLOutput(new FileOutputStream(name)) );
108     }
109 }