1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.myfaces.taglib.core;
20
21 import javax.el.ELException;
22 import javax.el.ValueExpression;
23 import javax.faces.FacesException;
24 import javax.faces.component.StateHolder;
25 import javax.faces.context.FacesContext;
26 import javax.faces.event.AbortProcessingException;
27 import javax.faces.event.ValueChangeEvent;
28 import javax.faces.event.ValueChangeListener;
29
30 /**
31 * This class is used in conjunction with ValueChangeListenerTag.
32 *
33 * When a tag like this is in a jsp page:
34 *
35 * <f:valueChangeListener binding="#{mybean}"/>
36 *
37 * or
38 *
39 * <f:valueChangeListener type="#{'anyid'}" binding="#{mybean}"/>
40 *
41 * The value of mybean could be already on the context, so this converter avoid creating a new variable and use the
42 * previous one.
43 *
44 * @author Leonardo Uribe (latest modification by $Author$)
45 * @version $Revision$ $Date$
46 */
47 public class DelegateValueChangeListener implements ValueChangeListener, StateHolder
48 {
49
50 private ValueExpression _type;
51 private ValueExpression _binding;
52
53 public DelegateValueChangeListener()
54 {
55 }
56
57 public DelegateValueChangeListener(ValueExpression type, ValueExpression binding)
58 {
59 super();
60 _type = type;
61 _binding = binding;
62 }
63
64 public boolean isTransient()
65 {
66 return false;
67 }
68
69 public void restoreState(FacesContext facesContext, Object state)
70 {
71 Object[] values = (Object[]) state;
72 _type = (ValueExpression) values[0];
73 _binding = (ValueExpression) values[1];
74 }
75
76 public Object saveState(FacesContext facesContext)
77 {
78 Object[] values = new Object[2];
79 values[0] = _type;
80 values[1] = _binding;
81 return values;
82 }
83
84 public void setTransient(boolean arg0)
85 {
86 // Do nothing
87 }
88
89 private ValueChangeListener _getDelegate()
90 {
91 return _createValueChangeListener();
92 }
93
94 private ValueChangeListener _createValueChangeListener()
95 {
96 FacesContext facesContext = FacesContext.getCurrentInstance();
97 ValueChangeListener listener = null;
98 // type and/or binding must be specified
99 try
100 {
101 if (null != _binding)
102 {
103 try
104 {
105 listener = (ValueChangeListener)_binding.getValue(facesContext.getELContext());
106 if (null != listener)
107 {
108 return listener;
109 }
110 }
111 catch (ELException e)
112 {
113 // throw new JspException("Exception while evaluating the binding attribute of Component "
114 // + component.getId(), e);
115 }
116 }
117
118 if (null != _type)
119 {
120 // FIXME: The listener never get created, check when this class is really used.
121 /*String className;
122 if (_type.isLiteralText())
123 {
124 className = _type.getExpressionString();
125 }
126 else
127 {
128 className = (String) _type.getValue(facesContext.getELContext());
129 }*/
130
131 listener = null;
132 // listener = (ActionListener) ClassUtils.newInstance(className);
133 if (null != _binding)
134 {
135 try
136 {
137 _binding.setValue(facesContext.getELContext(), listener);
138 }
139 catch (ELException e)
140 {
141 // throw new JspException("Exception while evaluating the binding attribute of Component "
142 // + component.getId(), e);
143 }
144 }
145
146 return listener;
147 }
148 }
149 catch (ClassCastException e)
150 {
151 throw new FacesException(e);
152 }
153
154 return listener;
155 }
156
157 public void processValueChange(ValueChangeEvent event) throws AbortProcessingException
158 {
159 _getDelegate().processValueChange(event);
160 }
161 }