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Java > Open Source Codes > org > apache > turbine > pipeline > ConditionalValve


1 package org.apache.turbine.pipeline;
2
3 /* ====================================================================
4  * The Apache Software License, Version 1.1
5  *
6  * Copyright (c) 2001 The Apache Software Foundation. All rights
7  * 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:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution,
22  * if any, must include the following acknowledgment:
23  * "This product includes software developed by the
24  * Apache Software Foundation (http://www.apache.org/)."
25  * Alternately, this acknowledgment may appear in the software itself,
26  * if and wherever such third-party acknowledgments normally appear.
27  *
28  * 4. The names "Apache" and "Apache Software Foundation" and
29  * "Apache Turbine" must not be used to endorse or promote products
30  * derived from this software without prior written permission. For
31  * written permission, please contact apache@apache.org.
32  *
33  * 5. Products derived from this software may not be called "Apache",
34  * "Apache Turbine", nor may "Apache" appear in their name, without
35  * prior written permission of the Apache Software Foundation.
36  *
37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
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50  *
51  * This software consists of voluntary contributions made by many
52  * individuals on behalf of the Apache Software Foundation. For more
53  * information on the Apache Software Foundation, please see
54  * <http://www.apache.org/>.
55  */
56
57 import java.io.BufferedReader JavaDoc;
58 import java.io.FileReader JavaDoc;
59 import java.io.IOException JavaDoc;
60 import java.io.Reader JavaDoc;
61
62 import org.apache.turbine.Pipeline;
63 import org.apache.turbine.RunData;
64 import org.apache.turbine.TurbineException;
65 import org.apache.turbine.Valve;
66 import org.apache.turbine.ValveContext;
67
68 import org.apache.commons.logging.Log;
69 import org.apache.commons.logging.LogFactory;
70
71 import com.thoughtworks.xstream.XStream;
72 import com.thoughtworks.xstream.io.xml.DomDriver;
73
74 /**
75  * Valve that conditionally executes a set of valves (internally
76  * contained in a <code>TurbinePipeline</code>).
77  *
78  * @author <a HREF="mailto:james@jamestaylor.org">James Taylor</a>
79  * @author <a HREF="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
80  * @version $Id: ConditionalValve.java,v 1.4 2004/11/01 19:10:15 epugh Exp $
81  */
82 public abstract class ConditionalValve
83     extends BranchPointValve
84 {
85     private static final Log log = LogFactory.getLog( ConditionalValve.class );
86     private static final String JavaDoc pipelineClassName =
87         "org.apache.turbine.pipeline.TurbinePipeline";
88
89     private String JavaDoc pipelineDescriptorPath;
90
91     /**
92      * Sets up our <code>TurbinePipeline</code> instance.
93      */
94     protected ConditionalValve()
95     {
96         pipelines = new Pipeline[] { new TurbinePipeline() };
97     }
98
99
100     public void setPipelineDescriptorPath(String JavaDoc pdp)
101     {
102         this.pipelineDescriptorPath = pdp;
103     }
104
105     /**
106      * Initializes all sub-pipelines.
107      *
108      * @see org.apache.turbine.Valve#initialize
109      */
110     public void initialize()
111         throws Exception JavaDoc
112     {
113             // Turbine's standard Pipeline implementation can use
114 // descriptors to define what Valves are attached to it.
115 if (pipelineDescriptorPath != null)
116         {
117             log.debug("ConditionalValve using descriptor path: "
118                       + pipelineDescriptorPath);
119             Reader JavaDoc reader = new BufferedReader JavaDoc(new FileReader JavaDoc(pipelineDescriptorPath));
120             XStream pipelineMapper = new XStream(new DomDriver()); // does not require XPP3 library
121 pipelines[0] = (Pipeline)
122             (Pipeline) pipelineMapper.fromXML(reader);
123         }
124         super.initialize();
125     }
126
127
128     /**
129      * Adds the provided valve to the contained pipeline.
130      */
131     public void addValve( Valve valve )
132     {
133         pipelines[0].addValve( valve );
134     }
135
136     /**
137      * @see org.apache.turbine.Valve#invoke
138      */
139     public void invoke( RunData data, ValveContext context )
140         throws IOException JavaDoc, TurbineException
141     {
142         if ( shouldInvoke( data ) )
143         {
144             log.debug("Invoking conditional pipeline");
145             pipelines[0].invoke( data );
146         }
147
148         context.invokeNext( data );
149     }
150
151     /**
152      * Determine whether the contained valves should be
153      * run. Subclasses should implement this method.
154      *
155      * @return Whether the contained valves should be run.
156      */
157     protected abstract boolean shouldInvoke( RunData data );
158 }
159
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