View Javadoc

1   /*
2    * $Id: StrutsResultSupport.java 471756 2006-11-06 15:01:43Z husted $
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  package org.apache.struts2.dispatcher;
22  
23  import java.io.UnsupportedEncodingException;
24  import java.net.URLEncoder;
25  
26  import org.apache.commons.logging.Log;
27  import org.apache.commons.logging.LogFactory;
28  import org.apache.struts2.StrutsStatics;
29  
30  import com.opensymphony.xwork2.ActionInvocation;
31  import com.opensymphony.xwork2.Result;
32  import com.opensymphony.xwork2.util.TextParseUtil;
33  
34  
35  /***
36   * <!-- START SNIPPET: javadoc -->
37   *
38   * A base class for all Struts action execution results.
39   * The "location" param is the default parameter, meaning the most common usage of this result would be:
40   * <p/>
41   * This class provides two common parameters for any subclass:
42   * <ul>
43   * <li>location - the location to go to after execution (could be a jsp page or another action).
44   * It can be parsed as per the rules definied in the
45   * {@link TextParseUtil#translateVariables(java.lang.String, com.opensymphony.xwork2.util.ValueStack) translateVariables}
46   * method</li>
47   * <li>parse - true by default. If set to false, the location param will not be parsed for expressions</li>
48   * <li>encode - false by default. If set to false, the location param will not be url encoded. This only have effect when parse is true</li>
49   * </ul>
50   *
51   * <b>NOTE:</b>
52   * The encode param will only have effect when parse is true
53   *
54   * <!-- END SNIPPET: javadoc -->
55   *
56   * <p/>
57   *
58   * <!-- START SNIPPET: example -->
59   *
60   * <p/>
61   * In the struts.xml configuration file, these would be included as:
62   * <p/>
63   * <pre>
64   *  &lt;result name="success" type="redirect"&gt;
65   *      &lt;param name="<b>location</b>"&gt;foo.jsp&lt;/param&gt;
66   *  &lt;/result&gt;</pre>
67   * <p/>
68   * or
69   * <p/>
70   * <pre>
71   *  &lt;result name="success" type="redirect" &gt;
72   *      &lt;param name="<b>location</b>"&gt;foo.jsp?url=${myUrl}&lt;/param&gt;
73   *      &lt;param name="<b>parse</b>"&gt;true&lt;/param&gt;
74   *      &lt;param name="<b>encode</b>"&gt;true&lt;/param&gt;
75   *  &lt;/result&gt;</pre>
76   * <p/>
77   * In the above case, myUrl will be parsed against Ognl Value Stack and then
78   * URL encoded.
79   * <p/>
80   * or when using the default parameter feature
81   * <p/>
82   * <pre>
83   *  &lt;result name="success" type="redirect"&gt;<b>foo.jsp</b>&lt;/result&gt;</pre>
84   * <p/>
85   * You should subclass this class if you're interested in adding more parameters or functionality
86   * to your Result. If you do subclass this class you will need to
87   * override {@link #doExecute(String, ActionInvocation)}.<p>
88   * <p/>
89   * Any custom result can be defined in struts.xml as:
90   * <p/>
91   * <pre>
92   *  &lt;result-types&gt;
93   *      ...
94   *      &lt;result-type name="myresult" class="com.foo.MyResult" /&gt;
95   *  &lt;/result-types&gt;</pre>
96   * <p/>
97   * Please see the {@link com.opensymphony.xwork2.Result} class for more info on Results in general.
98   *
99   * <!-- END SNIPPET: example -->
100  *
101  * @see com.opensymphony.xwork2.Result
102  */
103 public abstract class StrutsResultSupport implements Result, StrutsStatics {
104 
105     private static final Log _log = LogFactory.getLog(StrutsResultSupport.class);
106 
107     /*** The default parameter */
108     public static final String DEFAULT_PARAM = "location";
109 
110     private boolean parse;
111     private boolean encode;
112     private String location;
113     private String lastFinalLocation;
114 
115     public StrutsResultSupport() {
116         this(null, true, false);
117     }
118 
119     public StrutsResultSupport(String location) {
120         this(location, false, false);
121     }
122 
123     public StrutsResultSupport(String location, boolean parse, boolean encode) {
124         this.location = location;
125         this.parse = parse;
126         this.encode = encode;
127     }
128 
129     /***
130      * The location to go to after action execution. This could be a JSP page or another action.
131      * The location can contain OGNL expressions which will be evaulated if the <tt>parse</tt>
132      * parameter is set to <tt>true</tt>.
133      *
134      * @param location the location to go to after action execution.
135      * @see #setParse(boolean)
136      */
137     public void setLocation(String location) {
138         this.location = location;
139     }
140 
141     /***
142      * Returns the last parsed and encoded location value
143      */
144     public String getLastFinalLocation() {
145         return lastFinalLocation;
146     }
147 
148     /***
149      * Set parse to <tt>true</tt> to indicate that the location should be parsed as an OGNL expression. This
150      * is set to <tt>true</tt> by default.
151      *
152      * @param parse <tt>true</tt> if the location parameter is an OGNL expression, <tt>false</tt> otherwise.
153      */
154     public void setParse(boolean parse) {
155         this.parse = parse;
156     }
157 
158     /***
159      * Set encode to <tt>true</tt> to indicate that the location should be url encoded. This is set to
160      * <tt>true</tt> by default
161      *
162      * @param encode <tt>true</tt> if the location parameter should be url encode, <tt>false</tt> otherwise.
163      */
164     public void setEncode(boolean encode) {
165         this.encode = encode;
166     }
167 
168     /***
169      * Implementation of the <tt>execute</tt> method from the <tt>Result</tt> interface. This will call
170      * the abstract method {@link #doExecute(String, ActionInvocation)} after optionally evaluating the
171      * location as an OGNL evaluation.
172      *
173      * @param invocation the execution state of the action.
174      * @throws Exception if an error occurs while executing the result.
175      */
176     public void execute(ActionInvocation invocation) throws Exception {
177         lastFinalLocation = conditionalParse(location, invocation);
178         doExecute(lastFinalLocation, invocation);
179     }
180 
181     /***
182      * Parses the parameter for OGNL expressions against the valuestack
183      *
184      * @param param The parameter value
185      * @param invocation The action invocation instance
186      * @return The resulting string
187      */
188     protected String conditionalParse(String param, ActionInvocation invocation) {
189         if (parse && param != null && invocation != null) {
190             return TextParseUtil.translateVariables(param, invocation.getStack(),
191                     new TextParseUtil.ParsedValueEvaluator() {
192                         public Object evaluate(Object parsedValue) {
193                             if (encode) {
194                                 if (parsedValue != null) {
195                                     try {
196                                         // use UTF-8 as this is the recommended encoding by W3C to
197                                         // avoid incompatibilities.
198                                         return URLEncoder.encode(parsedValue.toString(), "UTF-8");
199                                     }
200                                     catch(UnsupportedEncodingException e) {
201                                         _log.warn("error while trying to encode ["+parsedValue+"]", e);
202                                     }
203                                 }
204                             }
205                             return parsedValue;
206                         }
207             });
208         } else {
209             return param;
210         }
211     }
212 
213     /***
214      * Executes the result given a final location (jsp page, action, etc) and the action invocation
215      * (the state in which the action was executed). Subclasses must implement this class to handle
216      * custom logic for result handling.
217      *
218      * @param finalLocation the location (jsp page, action, etc) to go to.
219      * @param invocation    the execution state of the action.
220      * @throws Exception if an error occurs while executing the result.
221      */
222     protected abstract void doExecute(String finalLocation, ActionInvocation invocation) throws Exception;
223 }