1 /*
2 * $Id: TilesContextBeanELResolver.java 816924 2009-09-19 13:45:40Z 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 package org.apache.tiles.el;
22
23 import java.beans.FeatureDescriptor;
24 import java.util.ArrayList;
25 import java.util.Iterator;
26 import java.util.List;
27 import java.util.Map;
28
29 import javax.el.ELContext;
30 import javax.el.ELResolver;
31
32 import org.apache.tiles.TilesApplicationContext;
33 import org.apache.tiles.context.TilesRequestContext;
34
35 /**
36 * Resolves beans in request, session and application scope.
37 *
38 * @version $Rev: 816924 $ $Date: 2009-09-19 15:45:40 +0200 (sab, 19 set 2009) $
39 * @since 2.2.1
40 */
41 public class TilesContextBeanELResolver extends ELResolver {
42
43 /** {@inheritDoc} */
44 @Override
45 public Class<?> getCommonPropertyType(ELContext context, Object base) {
46 // only resolve at the root of the context
47 if (base != null) {
48 return null;
49 }
50
51 return String.class;
52 }
53
54 /** {@inheritDoc} */
55 @Override
56 public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context,
57 Object base) {
58 List<FeatureDescriptor> list = new ArrayList<FeatureDescriptor>();
59
60 TilesRequestContext request = (TilesRequestContext) context
61 .getContext(TilesRequestContext.class);
62 collectBeanInfo(request.getRequestScope(), list);
63 collectBeanInfo(request.getSessionScope(), list);
64
65 TilesApplicationContext applicationContext = (TilesApplicationContext) context
66 .getContext(TilesApplicationContext.class);
67 collectBeanInfo(applicationContext.getApplicationScope(), list);
68 return list.iterator();
69 }
70
71 /** {@inheritDoc} */
72 @Override
73 public Class<?> getType(ELContext context, Object base, Object property) {
74 if (base != null) {
75 return null;
76 }
77
78 Object obj = findObjectByProperty(context, property);
79 if (obj != null) {
80 context.setPropertyResolved(true);
81 return obj.getClass();
82 }
83 return null;
84 }
85
86 /** {@inheritDoc} */
87 @Override
88 public Object getValue(ELContext context, Object base, Object property) {
89 if (base != null) {
90 return null;
91 }
92
93 Object retValue = findObjectByProperty(context, property);
94
95 if (retValue != null) {
96 context.setPropertyResolved(true);
97 }
98
99 return retValue;
100 }
101
102 /** {@inheritDoc} */
103 @Override
104 public boolean isReadOnly(ELContext context, Object base, Object property) {
105 if (context == null) {
106 throw new NullPointerException();
107 }
108
109 return true;
110 }
111
112 /** {@inheritDoc} */
113 @Override
114 public void setValue(ELContext context, Object base, Object property,
115 Object value) {
116 // Does nothing for the moment.
117 }
118
119 /**
120 * Collects bean infos from a map's values and filling a list.
121 *
122 * @param map The map containing the bean to be inspected.
123 * @param list The list to fill.
124 * @since 2.2.1
125 */
126 protected void collectBeanInfo(Map<String, ? extends Object> map,
127 List<FeatureDescriptor> list) {
128 if (map == null || map.isEmpty()) {
129 return;
130 }
131
132 for (Map.Entry<String, ? extends Object> entry : map.entrySet()) {
133 FeatureDescriptor descriptor = new FeatureDescriptor();
134 descriptor.setDisplayName(entry.getKey());
135 descriptor.setExpert(false);
136 descriptor.setHidden(false);
137 descriptor.setName(entry.getKey());
138 descriptor.setPreferred(true);
139 descriptor.setShortDescription("");
140 descriptor.setValue("type", String.class);
141 descriptor.setValue("resolvableAtDesignTime", Boolean.FALSE);
142 list.add(descriptor);
143 }
144 }
145
146 /**
147 * Finds an object in request, session or application scope, in this order.
148 *
149 * @param context The context to use.
150 * @param property The property used as an attribute name.
151 * @return The found bean, if it exists, or <code>null</code> otherwise.
152 * @since 2.2.1
153 */
154 protected Object findObjectByProperty(ELContext context, Object property) {
155 Object retValue = null;
156
157 TilesRequestContext request = (TilesRequestContext) context
158 .getContext(TilesRequestContext.class);
159
160 String prop = property.toString();
161
162 retValue = getObject(request.getRequestScope(), prop);
163 if (retValue == null) {
164 retValue = getObject(request.getSessionScope(), prop);
165 if (retValue == null) {
166 TilesApplicationContext applicationContext = (TilesApplicationContext) context
167 .getContext(TilesApplicationContext.class);
168 retValue = getObject(applicationContext.getApplicationScope(),
169 prop);
170 }
171 }
172
173 return retValue;
174 }
175
176 /**
177 * Returns an object from a map in a null-safe manner.
178 *
179 * @param map The map to use.
180 * @param property The property to use as a key.
181 * @return The object, if present, or <code>null</code> otherwise.
182 * @since 2.2.1
183 */
184 protected Object getObject(Map<String, ? extends Object> map,
185 String property) {
186 Object retValue = null;
187 if (map != null) {
188 retValue = map.get(property);
189 }
190 return retValue;
191 }
192 }