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1   /*
2    * $Id: GenericUIBean.java 651946 2008-04-27 13:41:38Z apetrelli $
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  
22  package org.apache.struts2.components;
23  
24  import javax.servlet.http.HttpServletRequest;
25  import javax.servlet.http.HttpServletResponse;
26  
27  import org.apache.struts2.views.annotations.StrutsTag;
28  import org.apache.struts2.util.ContainUtil;
29  
30  import com.opensymphony.xwork2.util.ValueStack;
31  
32  /***
33   * <!-- START SNIPPET: javadoc -->
34   *
35   * Renders an custom UI widget using the specified templates. Additional objects can be passed in to the template
36   * using the param tags.<p/>
37   *
38   * <b>Freemarker:</b><p/>
39   * Objects provided can be retrieve from within the template via $parameters._paramname_.<p/>
40   *
41   * <b>Jsp:</b><p/>
42   * Objects provided can be retrieve from within the template via &lt;s:property value="%{parameters._paramname_}" /&gt;<p/>
43   *
44   *
45   * In the bottom JSP and Velocity samples, two parameters are being passed in to the component. From within the
46   * component, they can be accessed as:- <p/>
47   *
48   * <b>Freemarker:</b><p/>
49   * $parameters.get('key1') and $parameters.get('key2') or $parameters.key1 and $parameters.key2<p/>
50   *
51   * <b>Jsp:</b><p/>
52   * &lt;s:property value="%{parameters.key1}" /&gt; and &lt;s:property value="%{'parameters.key2'}" /&gt; or
53   * &lt;s:property value="%{parameters.get('key1')}" /&gt; and &lt;s:property value="%{parameters.get('key2')}" /&gt;<p/>
54   *
55   * Currently, your custom UI components can be written in Velocity, JSP, or Freemarker, and the correct rendering
56   * engine will be found based on file extension.<p/>
57   *
58   * <b>Remember:</b> the value params will always be resolved against the ValueStack so if you mean to pass a
59   * string literal to your component, make sure to wrap it in quotes i.e. value="'value1'" otherwise, the the value
60   * stack will search for an Object on the stack with a method of getValue1(). (now that i've written this, i'm not
61   * entirely sure this is the case. i should verify this manana)<p/>
62   *
63   * <!-- END SNIPPET: javadoc -->
64   *
65   * <p/> <b>Examples</b>
66   *
67   * <pre>
68   * <!-- START SNIPPET: example -->
69   * JSP
70   *     &lt;s:component template="/my/custom/component.vm"/&gt;
71   *
72   *       or
73   *
74   *     &lt;s:component template="/my/custom/component.vm"&gt;
75   *       &lt;s:param name="key1" value="value1"/&gt;
76   *       &lt;s:param name="key2" value="value2"/&gt;
77   *     &lt;/s:component&gt;
78   *
79   * Velocity
80   *     #s-component( "template=/my/custom/component.vm" )
81   *
82   *       or
83   *
84   *     #s-component( "template=/my/custom/component.vm" )
85   *       #s-param( "name=key1" "value=value1" )
86   *       #s-param( "name=key2" "value=value2" )
87   *     #end
88   *
89   * Freemarker
90   *    &lt;@s..component template="/my/custom/component.ftl" />
91   *
92   *      or
93   *
94   *    &lt;@s..component template="/my/custom/component.ftl"&gt;
95   *       &lt;@s..param name="key1" value="%{'value1'}" /&gt;
96   *       &lt;@s..param name="key2" value="%{'value2'}" /&gt;
97   *    &lt;/@s..component&gt;
98   *
99   * <!-- END SNIPPET: example -->
100  * </pre>
101  *
102  * <p/>
103  *
104  * <b>NOTE:</b>
105  * <!-- START SNIPPET: note -->
106  *
107  * If Jsp is used as the template, the jsp template itself must lie within the
108  * webapp itself and not the classpath. Unlike Freemarker or Velocity, JSP template
109  * could not be picked up from the classpath.
110  *
111  * <!-- END SNIPPET: note -->
112  *
113  */
114 @StrutsTag(name="component", tldTagClass="org.apache.struts2.views.jsp.ui.ComponentTag", description="Render a custom ui widget")
115 public class GenericUIBean extends UIBean {
116     private final static String TEMPLATE = "empty";
117 
118     public GenericUIBean(ValueStack stack, HttpServletRequest request, HttpServletResponse response) {
119         super(stack, request, response);
120     }
121 
122     public boolean contains(Object obj1, Object obj2) {
123         return ContainUtil.contains(obj1, obj2);
124     }
125 
126     protected String getDefaultTemplate() {
127         return TEMPLATE;
128     }
129 }