WireFeedOutput


1   /*
2    * Copyright 2004 Sun Microsystems, Inc.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   *
16   */
17  package com.sun.syndication.io;
18  
19  import com.sun.syndication.feed.WireFeed;
20  import com.sun.syndication.io.impl.FeedGenerators;
21  import org.jdom.Document;
22  import org.jdom.JDOMException;
23  import org.jdom.output.DOMOutputter;
24  import org.jdom.output.Format;
25  import org.jdom.output.XMLOutputter;
26  
27  import java.io.IOException  ;
28  import java.io.Writer  ;
29  import java.io.File  ;
30  import java.io.FileWriter  ;
31  import java.util.List  ;
32  
33  /**
34   * Generates an XML document (String, File, OutputStream, Writer, W3C DOM document or JDOM document)
35   * out of an WireFeed (RSS/Atom).
36   * <p>
37   * It generates all flavors of RSS (0.90, 0.91, 0.92, 0.93, 0.94, 1.0 and 2.0) and
38   * Atom 0.3 feeds. Generators are plugable (they must implement the ModuleParser interface).
39   * <p>
40   * @author Alejandro Abdelnur
41   *
42   */
43  public class WireFeedOutput {
44      private final static FeedGenerators GENERATORS = new FeedGenerators();
45  
46      /**
47       * Returns the list of supported output feed types.
48       * <p>
49       * @see WireFeed for details on the format of these strings.
50       * <p>
51       * @return a list of String elements with the supported output feed types.
52       *
53       */
54      public static List   getSupportedFeedTypes() {
55          return GENERATORS.getSupportedFeedTypes();
56      }
57  
58      /**
59       * Creates a FeedOuput instance.
60       * <p>
61       *
62       */
63      public WireFeedOutput() {
64      }
65  
66      /**
67       * Creates a String with the XML representation for the given WireFeed.
68       * <p>
69       * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. It is the responsibility
70       * of the developer to ensure that if the String is written to a character stream the stream charset is the same as
71       * the feed encoding property.
72       * <p>
73       * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
74       * <p>
75       * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match
76       *        the type given to the FeedOuptut constructor.
77       * @return a String with the XML representation for the given WireFeed.
78       * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
79       * @throws FeedException thrown if the XML representation for the feed could not be created.
80       *
81       */
82      public String   outputString(WireFeed feed) throws IllegalArgumentException  ,FeedException {
83          Document doc = outputJDom(feed);
84          String   encoding = feed.getEncoding();
85          Format format = Format.getPrettyFormat();
86          if (encoding!=null) {
87              format.setEncoding(encoding);
88          }
89          XMLOutputter outputter = new XMLOutputter(format);
90          return outputter.outputString(doc);
91      }
92  
93      /**
94       * Creates a File containing with the XML representation for the given WireFeed.
95       * <p>
96       * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. The platform
97       * default charset encoding is used to write the feed to the file. It is the responsibility
98       * of the developer to ensure the feed encoding is set to the platform charset encoding.
99       * <p>
100      * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
101      * <p>
102      * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match
103      *        the type given to the FeedOuptut constructor.
104      * @param file the file where to write the XML representation for the given WireFeed.
105      * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
106      * @throws IOException thrown if there was some problem writing to the File.
107      * @throws FeedException thrown if the XML representation for the feed could not be created.
108      *
109      */
110     public void output(WireFeed feed,File   file) throws IllegalArgumentException  ,IOException  ,FeedException {
111         Writer   writer = new FileWriter  (file);
112         output(feed,writer);
113         writer.close();
114     }
115 
116     /**
117      * Writes to an Writer the XML representation for the given WireFeed.
118      * <p>
119      * If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. It is the responsibility
120      * of the developer to ensure the Writer instance is using the same charset encoding.
121      * <p>
122      * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
123      * <p>
124      * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match
125      *        the type given to the FeedOuptut constructor.
126      * @param writer Writer to write the XML representation for the given WireFeed.
127      * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
128      * @throws IOException thrown if there was some problem writing to the Writer.
129      * @throws FeedException thrown if the XML representation for the feed could not be created.
130      *
131      */
132     public void output(WireFeed feed,Writer   writer) throws IllegalArgumentException  ,IOException  , FeedException {
133         Document doc = outputJDom(feed);
134         String   encoding = feed.getEncoding();
135         Format format = Format.getPrettyFormat();
136         if (encoding!=null) {
137             format.setEncoding(encoding);
138         }
139         XMLOutputter outputter = new XMLOutputter(format);
140         outputter.output(doc,writer);
141     }
142 
143     /**
144      * Creates a W3C DOM document for the given WireFeed.
145      * <p>
146      * This method does not use the feed encoding property.
147      * <p>
148      * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
149      * <p>
150      * @param feed Abstract feed to create W3C DOM document from. The type of the WireFeed must match
151      *        the type given to the FeedOuptut constructor.
152      * @return the W3C DOM document for the given WireFeed.
153      * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
154      * @throws FeedException thrown if the W3C DOM document for the feed could not be created.
155      *
156      */
157     public org.w3c.dom.Document   outputW3CDom(WireFeed feed) throws IllegalArgumentException  ,FeedException {
158         Document doc = outputJDom(feed);
159         DOMOutputter outputter = new DOMOutputter();
160         try {
161             return outputter.output(doc);
162         }
163         catch (JDOMException jdomEx) {
164             throw new FeedException("Could not create DOM",jdomEx);
165         }
166     }
167 
168     /**
169      * Creates a JDOM document for the given WireFeed.
170      * <p>
171      * This method does not use the feed encoding property.
172      * <p>
173      * NOTE: All other output methods delegate to this method.
174      * <p>
175      * @param feed Abstract feed to create JDOM document from. The type of the WireFeed must match
176      *        the type given to the FeedOuptut constructor.
177      * @return the JDOM document for the given WireFeed.
178      * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
179      * @throws FeedException thrown if the JDOM document for the feed could not be created.
180      *
181      */
182     public Document outputJDom(WireFeed feed) throws IllegalArgumentException  ,FeedException {
183         String   type = feed.getFeedType();
184         WireFeedGenerator generator = GENERATORS.getGenerator(type);
185         if (generator==null) {
186             throw new IllegalArgumentException  ("Invalid feed type ["+type+"]");
187         }
188 
189         if (!generator.getType().equals(type)) {
190             throw new IllegalArgumentException  ("WireFeedOutput type["+type+"] and WireFeed type ["+
191                                                type+"] don't match");
192         }
193         return generator.generate(feed);
194     }
195 
196 }
197
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