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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       * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
70       * <p>
71       * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match
72       *        the type given to the FeedOuptut constructor.
73       * @return a String with the XML representation for the given WireFeed.
74       * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
75       * @throws FeedException thrown if the XML representation for the feed could not be created.
76       *
77       */
78      public String outputString(WireFeed feed) throws IllegalArgumentException,FeedException {
79          Document doc = outputJDom(feed);
80          XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat());
81          return outputter.outputString(doc);
82      }
83  
84      /***
85       * Creates a File containing with the XML representation for the given WireFeed.
86       * <p>
87       * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
88       * <p>
89       * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match
90       *        the type given to the FeedOuptut constructor.
91       * @param file the file where to write the XML representation for the given WireFeed.
92       * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
93       * @throws IOException thrown if there was some problem writing to the File.
94       * @throws FeedException thrown if the XML representation for the feed could not be created.
95       *
96       */
97      public void output(WireFeed feed,File file) throws IllegalArgumentException,IOException,FeedException {
98          Writer writer = new FileWriter(file);
99          output(feed,writer);
100         writer.close();
101     }
102 
103     /***
104      * Writes to an Writer the XML representation for the given WireFeed.
105      * <p>
106      * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
107      * <p>
108      * @param feed Abstract feed to create XML representation from. The type of the WireFeed must match
109      *        the type given to the FeedOuptut constructor.
110      * @param writer Writer to write the XML representation for the given WireFeed.
111      * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
112      * @throws IOException thrown if there was some problem writing to the Writer.
113      * @throws FeedException thrown if the XML representation for the feed could not be created.
114      *
115      */
116     public void output(WireFeed feed,Writer writer) throws IllegalArgumentException,IOException, FeedException {
117         Document doc = outputJDom(feed);
118         XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat());
119         outputter.output(doc,writer);
120     }
121 
122     /***
123      * Creates a W3C DOM document for the given WireFeed.
124      * <p>
125      * NOTE: This method delages to the 'Document WireFeedOutput#outputJDom(WireFeed)'.
126      * <p>
127      * @param feed Abstract feed to create W3C DOM document from. The type of the WireFeed must match
128      *        the type given to the FeedOuptut constructor.
129      * @return the W3C DOM document for the given WireFeed.
130      * @throws IllegalArgumentException thrown if the feed type of the WireFeedOutput and WireFeed don't match.
131      * @throws FeedException thrown if the W3C DOM document for the feed could not be created.
132      *
133      */
134     public org.w3c.dom.Document outputW3CDom(WireFeed feed) throws IllegalArgumentException,FeedException {
135         Document doc = outputJDom(feed);
136         DOMOutputter outputter = new DOMOutputter();
137         try {
138             return outputter.output(doc);
139         }
140         catch (JDOMException jdomEx) {
141             throw new FeedException("Could not create DOM",jdomEx);
142         }
143     }
144 
145     /***
146      * Creates a JDOM document for the given WireFeed.
147      * <p>
148      * NOTE: All other output methods delegate to this method.
149      * <p>
150      * @param feed Abstract feed to create JDOM document from. The type of the WireFeed must match
151      *        the type given to the FeedOuptut constructor.
152      * @return the JDOM 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 JDOM document for the feed could not be created.
155      *
156      */
157     public Document outputJDom(WireFeed feed) throws IllegalArgumentException,FeedException {
158         String type = feed.getFeedType();
159         WireFeedGenerator generator = GENERATORS.getGenerator(type);
160         if (generator==null) {
161             throw new IllegalArgumentException("Invalid feed type ["+type+"]");
162         }
163 
164         if (!generator.getType().equals(type)) {
165             throw new IllegalArgumentException("WireFeedOutput type["+type+"] and WireFeed type ["+
166                                                type+"] don't match");
167         }
168         return generator.generate(feed);
169     }
170 
171 }