View Javadoc

1   /*
2    * $Id: GetAsStringModel.java 797765 2009-07-25 13:20:26Z 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.tiles.template;
23  
24  import java.io.IOException;
25  import java.io.Writer;
26  
27  import org.apache.tiles.ArrayStack;
28  import org.apache.tiles.Attribute;
29  import org.apache.tiles.TilesContainer;
30  import org.slf4j.Logger;
31  import org.slf4j.LoggerFactory;
32  
33  /***
34   * <p>
35   * <strong> Render the value of the specified template attribute to the current
36   * Writer</strong>
37   * </p>
38   *
39   * <p>
40   * Retrieve the value of the specified template attribute property, and render
41   * it to the current Writer as a String. The usual toString() conversions is
42   * applied on found value.
43   * </p>
44   *
45   * @version $Rev: 797765 $ $Date: 2009-07-25 15:20:26 +0200 (sab, 25 lug 2009) $
46   * @since 2.2.0
47   */
48  public class GetAsStringModel {
49  
50      /***
51       * The logging object.
52       */
53      private Logger log = LoggerFactory.getLogger(getClass());
54  
55      /***
56       * The attribute resolver to use.
57       */
58      private AttributeResolver attributeResolver;
59  
60      /***
61       * Constructor.
62       *
63       * @param attributeResolver The attribute resolver to use.
64       * @since 2.2.0
65       */
66      public GetAsStringModel(AttributeResolver attributeResolver) {
67          this.attributeResolver = attributeResolver;
68      }
69  
70      /***
71       * Starts the operation.
72       *
73       * @param composeStack The compose stack,
74       * @param container The Tiles container to use.
75       * @param ignore If <code>true</code>, if an exception happens during
76       * rendering, of if the attribute is null, the problem will be ignored.
77       * @param preparer The preparer to invoke before rendering the attribute.
78       * @param role A comma-separated list of roles. If present, the attribute
79       * will be rendered only if the current user belongs to one of the roles.
80       * @param defaultValue The default value of the attribute. To use only if
81       * the attribute was not computed.
82       * @param defaultValueRole The default comma-separated list of roles. To use
83       * only if the attribute was not computed.
84       * @param defaultValueType The default type of the attribute. To use only if
85       * the attribute was not computed.
86       * @param name The name of the attribute.
87       * @param value The attribute to use immediately, if not null.
88       * @param requestItems The request objects.
89       * @since 2.2.0
90       */
91      public void start(ArrayStack<Object> composeStack, TilesContainer container,
92              boolean ignore, String preparer, String role, Object defaultValue,
93              String defaultValueRole, String defaultValueType, String name,
94              Attribute value, Object... requestItems) {
95          Attribute attribute = resolveAttribute(container, ignore, preparer,
96                  role, defaultValue, defaultValueRole, defaultValueType, name,
97                  value, requestItems);
98          composeStack.push(attribute);
99      }
100 
101     /***
102      * Ends the operation.
103      *
104      * @param composeStack The compose stack,
105      * @param container The Tiles container to use.
106      * @param writer The writer into which the attribute will be written.
107      * @param ignore If <code>true</code>, if an exception happens during
108      * rendering, of if the attribute is null, the problem will be ignored.
109      * @param requestItems The request objects.
110      * @throws IOException If an I/O error happens during rendering.
111      */
112     public void end(ArrayStack<Object> composeStack, TilesContainer container,
113             Writer writer, boolean ignore, Object... requestItems)
114             throws IOException {
115         Attribute attribute = (Attribute) composeStack.pop();
116         renderAttribute(attribute, container, writer, ignore, requestItems);
117     }
118 
119     /***
120      * Executes the operation.
121      *
122      * @param container The Tiles container to use.
123      * @param writer The writer into which the attribute will be written.
124      * @param ignore If <code>true</code>, if an exception happens during
125      * rendering, of if the attribute is null, the problem will be ignored.
126      * @param preparer The preparer to invoke before rendering the attribute.
127      * @param role A comma-separated list of roles. If present, the attribute
128      * will be rendered only if the current user belongs to one of the roles.
129      * @param defaultValue The default value of the attribute. To use only if
130      * the attribute was not computed.
131      * @param defaultValueRole The default comma-separated list of roles. To use
132      * only if the attribute was not computed.
133      * @param defaultValueType The default type of the attribute. To use only if
134      * the attribute was not computed.
135      * @param name The name of the attribute.
136      * @param value The attribute to use immediately, if not null.
137      * @param requestItems The request objects.
138      * @throws IOException If an I/O error happens during rendering.
139      * @since 2.2.0
140      */
141     public void execute(TilesContainer container, Writer writer,
142             boolean ignore, String preparer, String role, Object defaultValue,
143             String defaultValueRole, String defaultValueType, String name,
144             Attribute value, Object... requestItems) throws IOException {
145         Attribute attribute = resolveAttribute(container, ignore, preparer,
146                 role, defaultValue, defaultValueRole, defaultValueType, name,
147                 value, requestItems);
148         renderAttribute(attribute, container, writer, ignore, requestItems);
149     }
150 
151     /***
152      * Resolves the attribute. and starts the context.
153      *
154      * @param container The Tiles container to use.
155      * @param ignore If <code>true</code>, if an exception happens during
156      * rendering, of if the attribute is null, the problem will be ignored.
157      * @param preparer The preparer to invoke before rendering the attribute.
158      * @param role A comma-separated list of roles. If present, the attribute
159      * will be rendered only if the current user belongs to one of the roles.
160      * @param defaultValue The default value of the attribute. To use only if
161      * the attribute was not computed.
162      * @param defaultValueRole The default comma-separated list of roles. To use
163      * only if the attribute was not computed.
164      * @param defaultValueType The default type of the attribute. To use only if
165      * the attribute was not computed.
166      * @param name The name of the attribute.
167      * @param value The attribute to use immediately, if not null.
168      * @param requestItems The request objects.
169      * @return The resolved attribute.
170      */
171     private Attribute resolveAttribute(TilesContainer container,
172             boolean ignore, String preparer, String role, Object defaultValue,
173             String defaultValueRole, String defaultValueType, String name,
174             Attribute value, Object... requestItems) {
175         if (preparer != null) {
176             container.prepare(preparer, requestItems);
177         }
178         Attribute attribute = attributeResolver.computeAttribute(container,
179                 value, name, role, ignore, defaultValue, defaultValueRole,
180                 defaultValueType, requestItems);
181         container.startContext(requestItems);
182         return attribute;
183     }
184 
185     /***
186      * Renders the attribute as a string.
187      *
188      * @param attribute The attribute to use, previously resolved.
189      * @param container The Tiles container to use.
190      * @param writer The writer into which the attribute will be written.
191      * @param ignore If <code>true</code>, if an exception happens during
192      * rendering, of if the attribute is null, the problem will be ignored.
193      * @param requestItems The request objects.
194      * @throws IOException If an I/O error happens during rendering.
195      */
196     private void renderAttribute(Attribute attribute, TilesContainer container,
197             Writer writer, boolean ignore, Object... requestItems)
198             throws IOException {
199         if (attribute == null && ignore) {
200             return;
201         }
202         try {
203             writer.write(attribute.getValue().toString());
204         } catch (IOException e) {
205             if (!ignore) {
206                 throw e;
207             } else if (log.isDebugEnabled()) {
208                 log.debug("Ignoring exception", e);
209             }
210         } catch (RuntimeException e) {
211             if (!ignore) {
212                 throw e;
213             } else if (log.isDebugEnabled()) {
214                 log.debug("Ignoring exception", e);
215             }
216         } finally {
217             container.endContext(requestItems);
218         }
219     }
220 }