XStreamMessageTransformer


1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one or more
4    * contributor license agreements.  See the NOTICE file distributed with
5    * this work for additional information regarding copyright ownership.
6    * The ASF licenses this file to You under the Apache License, Version 2.0
7    * (the "License"); you may not use this file except in compliance with
8    * the License.  You may obtain a copy of the License at
9    *
10   * http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.activemq.util.xstream;
19  
20  import com.thoughtworks.xstream.XStream;
21  import com.thoughtworks.xstream.io.HierarchicalStreamReader;
22  import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
23  import com.thoughtworks.xstream.io.xml.PrettyPrintWriter;
24  import com.thoughtworks.xstream.io.xml.XppReader;
25  import org.apache.activemq.MessageTransformerSupport;
26  
27  import javax.jms.JMSException  ;
28  import javax.jms.Message  ;
29  import javax.jms.MessageConsumer  ;
30  import javax.jms.MessageProducer  ;
31  import javax.jms.ObjectMessage  ;
32  import javax.jms.Session  ;
33  import javax.jms.TextMessage  ;
34  import java.io.Serializable  ;
35  import java.io.StringReader  ;
36  import java.io.StringWriter  ;
37  
38  /**
39   * Transforms object messages to text messages using {@link XStream}
40   *
41   * @version $Revision: 475701 $
42   */
43  public class XStreamMessageTransformer extends MessageTransformerSupport {
44      private XStream xStream;
45  
46  
47      public Message   producerTransform(Session   session, MessageProducer   producer, Message   message) throws JMSException   {
48          if (message instanceof ObjectMessage  ) {
49              TextMessage   answer = session.createTextMessage(marshall(session, producer, (ObjectMessage  ) message));
50              copyProperties(message, answer);
51              return answer;
52          }
53          return message;
54      }
55  
56  
57      public Message   consumerTransform(Session   session, MessageConsumer   consumer, Message   message) throws JMSException   {
58          if (message instanceof TextMessage  ) {
59              TextMessage   textMessage = (TextMessage  ) message;
60              Object   object = unmarshall(session, consumer, textMessage);
61              if (object instanceof Serializable  ) {
62                  ObjectMessage   answer = session.createObjectMessage((Serializable  ) object);
63                  copyProperties(message, answer);
64                  return answer;
65              }
66              else {
67                  throw new JMSException  ("Object is not serializable: " + object);
68              }
69          }
70          return message;
71      }
72  
73  
74      // Properties
75      // -------------------------------------------------------------------------
76      public XStream getXStream() {
77          if (xStream == null) {
78              xStream = createXStream();
79          }
80          return xStream;
81      }
82  
83      public void setXStream(XStream xStream) {
84          this.xStream = xStream;
85      }
86  
87      // Implementation methods
88      // -------------------------------------------------------------------------
89      protected XStream createXStream() {
90          return new XStream();
91      }
92  
93      /**
94       * Marshalls the Object in the {@link ObjectMessage} to a string using XML encoding
95       */
96      protected String   marshall(Session   session, MessageProducer   producer, ObjectMessage   objectMessage) throws JMSException   {
97          Serializable   object = objectMessage.getObject();
98          StringWriter   buffer = new StringWriter  ();
99          HierarchicalStreamWriter out = new PrettyPrintWriter(buffer);
100         getXStream().marshal(object, out);
101         return buffer.toString();
102     }
103 
104     /**
105      * Unmarshalls the Object using XML encoding of the String
106      */
107     protected Object   unmarshall(Session   session, MessageConsumer   consumer, TextMessage   textMessage) throws JMSException   {
108         HierarchicalStreamReader in = new XppReader(new StringReader  (textMessage.getText()));
109         return getXStream().unmarshal(in);
110     }
111 
112 }
113
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