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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.impl;
18  
19  import com.sun.syndication.io.WireFeedParser;
20  import org.jdom.Document;
21  
22  import java.util.ArrayList;
23  import java.util.Collections;
24  import java.util.List;
25  
26  /***
27   * Parses an XML document (JDOM Document) into a Feed.
28   * <p>
29   * It accepts all flavors of RSS (0.90, 0.91, 0.92, 0.93, 0.94, 1.0 and 2.0) and
30   * Atom 0.3 feeds.
31   * <p>
32   * The WireFeedParser is a liberal parser.
33   * <p>
34   * WireFeedParser instances are thread safe.
35   * <p>
36   * Parsers for a specific type must extend this class and register in the parser list.
37   * (Right now registration is hardcoded in the WireFeedParser constructor).
38   * <p>
39   * @author Alejandro Abdelnur
40   *
41   */
42  public class FeedParsers {
43      private List PARSERS;
44      private List TYPES;
45  
46      private List loadParsers(String defaultFile,String fileProperty) {
47          List list = new ArrayList();
48          PlugableClasses pClasses = new PlugableClasses(defaultFile,fileProperty,Constants.FEED_PARSERS_KEY,
49                                                         true,FeedParsers.class.getClassLoader());
50          Object[] parsers;
51          try {
52              parsers = pClasses.createInstances();
53          }
54          catch (Exception ex) {
55              throw new RuntimeException(ex);
56          }
57          for (int i=0;i<parsers.length;i++) {
58              WireFeedParser parser = (WireFeedParser) parsers[i];
59              list.add(parser);
60          }
61          return list;
62      }
63  
64      /***
65       * Creates a parser instance.
66       * <p>
67       *
68       */
69      public FeedParsers() {
70          this(Constants.DEFAULT_IMPLS_FILE,Constants.IMPLS_SYSTEM_PROPERTY);
71      }
72  
73      public FeedParsers(String defaultFile,String fileProperty) {
74          PARSERS = loadParsers(defaultFile,fileProperty);
75          List types = new ArrayList();
76          for (int i=0;i<PARSERS.size();i++) {
77              types.add(((WireFeedParser)PARSERS.get(i)).getType());
78          }
79          TYPES = Collections.unmodifiableList(types);
80      }
81  
82      public List getSupportedFeedTypes() {
83          return TYPES;
84      }
85  
86      /***
87       * Finds the real parser type for the given document feed.
88       * <p>
89       * @param document document feed to find the parser for.
90       * @return the parser for the given document or <b>null</b> if there is no parser for that document.
91       *
92       */
93      public WireFeedParser getParserFor(Document document) {
94          WireFeedParser parser = null;
95          for (int i=0;parser==null && i<PARSERS.size();i++) {
96              parser = (WireFeedParser) PARSERS.get(i);
97              if (!parser.isMyType(document)) {
98                  parser = null;
99              }
100         }
101         return parser;
102     }
103 
104 }