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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.util.PlugableClasses;
20  import com.sun.syndication.io.FeedParser;
21  import org.jdom.Document;
22  
23  import java.util.ArrayList;
24  import java.util.Collections;
25  import java.util.List;
26  
27  /***
28   * Parses an XML document (JDOM Document) into a Feed.
29   * <p>
30   * It accepts all flavors of RSS (0.90, 0.91, 0.92, 0.93, 0.94, 1.0 and 2.0) and
31   * Atom 0.3 feeds.
32   * <p>
33   * The FeedParser is a liberal parser.
34   * <p>
35   * FeedParser instances are thread safe.
36   * <p>
37   * Parsers for a specific type must extend this class and register in the parser list.
38   * (Right now registration is hardcoded in the FeedParser constructor).
39   * <p>
40   * @author Alejandro Abdelnur
41   *
42   */
43  public class FeedParsers {
44      private List PARSERS;
45      private List TYPES;
46  
47      private List loadParsers(String defaultFile,String fileProperty) {
48          List list = new ArrayList();
49          PlugableClasses pClasses = new PlugableClasses(defaultFile,fileProperty,Constants.FEED_PARSERS_KEY,
50                                                         true,FeedParsers.class.getClassLoader());
51          Object[] parsers;
52          try {
53              parsers = pClasses.createInstances();
54          }
55          catch (Exception ex) {
56              throw new RuntimeException(ex);
57          }
58          for (int i=0;i<parsers.length;i++) {
59              FeedParser parser = (FeedParser) parsers[i];
60              list.add(parser);
61          }
62          return list;
63      }
64  
65      /***
66       * Creates a parser instance.
67       * <p>
68       *
69       */
70      public FeedParsers() {
71          this(Constants.DEFAULT_IMPLS_FILE,Constants.IMPLS_SYSTEM_PROPERTY);
72      }
73  
74      public FeedParsers(String defaultFile,String fileProperty) {
75          PARSERS = loadParsers(defaultFile,fileProperty);
76          List types = new ArrayList();
77          for (int i=0;i<PARSERS.size();i++) {
78              types.add(((FeedParser)PARSERS.get(i)).getType());
79          }
80          TYPES = Collections.unmodifiableList(types);
81      }
82  
83      public List getSupportedFeedTypes() {
84          return TYPES;
85      }
86  
87      /***
88       * Finds the real parser type for the given document feed.
89       * <p>
90       * @param document document feed to find the parser for.
91       * @return the parser for the given document or <b>null</b> if there is no parser for that document.
92       *
93       */
94      public FeedParser getParserFor(Document document) {
95          FeedParser parser = null;
96          for (int i=0;parser==null && i<PARSERS.size();i++) {
97              parser = (FeedParser) PARSERS.get(i);
98              if (!parser.isMyType(document)) {
99                  parser = null;
100             }
101         }
102         return parser;
103     }
104 
105 }