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Java > Open Source Codes > org > apache > servicemix > expression > PropertyExpression


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 package org.apache.servicemix.expression;
18
19 import javax.jbi.messaging.MessageExchange;
20 import javax.jbi.messaging.MessagingException;
21 import javax.jbi.messaging.NormalizedMessage;
22
23 /**
24  * A simple expression which returns the value of a property on the message.
25  *
26  * @version $Revision: 426415 $
27  */
28 public class PropertyExpression implements Expression {
29     private String JavaDoc property;
30     private Object JavaDoc defaultValue;
31
32     public PropertyExpression(String JavaDoc property) {
33         this.property = property;
34     }
35
36     public PropertyExpression(String JavaDoc property, Object JavaDoc defaultValue) {
37         this.property = property;
38         this.defaultValue = defaultValue;
39     }
40
41     public Object JavaDoc evaluate(MessageExchange exchange, NormalizedMessage message) throws MessagingException {
42         Object JavaDoc answer = message.getProperty(property);
43         if (answer == null) {
44             answer = exchange.getProperty(property);
45             if (answer == null) {
46                 answer = defaultValue;
47             }
48         }
49         return answer;
50     }
51 }
52
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