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Java > Open Source Codes > org > objectstyle > cayenne > distribution > AbstractMessage


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
5  *
6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
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13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
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16  * 2. Redistributions in binary form must reproduce the above copyright
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19  * distribution.
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21  * 3. The end-user documentation included with the redistribution, if any,
22  * must include the following acknowlegement:
23  * "This product includes software developed by independent contributors
24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
27  *
28  * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
29  * or promote products derived from this software without prior written
30  * permission. For written permission, email
31  * "andrus at objectstyle dot org".
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34  * or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
35  * names without prior written permission.
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37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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51  * This software consists of voluntary contributions made by many
52  * individuals and hosted on ObjectStyle Group web site. For more
53  * information on the ObjectStyle Group, please see
54  * <http://objectstyle.org/>.
55  */
56 package org.objectstyle.cayenne.distribution;
57
58 import org.apache.commons.lang.builder.ToStringBuilder;
59 import org.objectstyle.cayenne.client.CayenneClientException;
60
61 /**
62  * A convenience common superclass of client messages.
63  *
64  * @since 1.2
65  * @author Andrus Adamchik
66  */
67 public abstract class AbstractMessage implements ClientMessage {
68
69     public abstract Object JavaDoc onReceive(ClientMessageHandler handler);
70
71     /**
72      * Convenience method to send this message over CayenneConnector and get a result of a
73      * specific class. Use by subclasses to implement safe casting of result.
74      *
75      * @throws org.objectstyle.cayenne.client.CayenneClientException if an underlying
76      * connector exception occured, or a result is not of expected type.
77      */
78     protected Object JavaDoc send(CayenneConnector connector, Class JavaDoc resultClass) {
79         Object JavaDoc result = connector.sendMessage(this);
80
81         if (result != null && !resultClass.isInstance(result)) {
82             String JavaDoc resultString = new ToStringBuilder(result).toString();
83             throw new CayenneClientException("Expected result type: "
84                     + resultClass.getName()
85                     + ", actual: "
86                     + resultString);
87         }
88
89         return result;
90     }
91 }
92
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