Document


1   package org.enhydra.snapper.wrapper.lucene;
2   
3   /**
4   
5    */
6   
7   import java.util.Enumeration  ;
8   import java.util.Iterator  ;
9   import java.util.List  ;
10  import java.util.ArrayList  ;
11  import java.util.Vector  ;
12  
13  
14  /** Documents are the unit of indexing and search.
15   *
16   * A Document is a set of fields.  Each field has a name and a textual value.
17   * A field may be {@link Field#isStored() stored} with the document, in which
18   * case it is returned with search hits on the document.  Thus each document
19   * should typically contain one or more stored fields which uniquely identify
20   * it.
21   *
22   * <p>Note that fields which are <i>not</i> {@link Field#isStored() stored} are
23   * <i>not</i> available in documents retrieved from the index, e.g. with {@link
24   * Hits#doc(int)}, {@link Searcher#doc(int)} or {@link
25   * IndexReader#document(int)}.
26   */
27  
28  public final class Document implements java.io.Serializable   {
29    List   fields = new Vector  ();
30    private float boost = 1.0f;
31  
32    /** Constructs a new document with no fields. */
33    public Document() {}
34  
35  
36    /** Sets a boost factor for hits on any field of this document.  This value
37     * will be multiplied into the score of all hits on this document.
38     *
39     * <p>Values are multiplied into the value of {@link Field#getBoost()} of
40     * each field in this document.  Thus, this method in effect sets a default
41     * boost for the fields of this document.
42     *
43     * @see Field#setBoost(float)
44     */
45    public void setBoost(float boost) {
46      this.boost = boost;
47    }
48  
49    /** Returns the boost factor for hits on any field of this document.
50     *
51     * <p>The default value is 1.0.
52     *
53     * <p>Note: This value is not stored directly with the document in the index.
54     * Documents returned from {@link IndexReader#document(int)} and
55     * {@link Hits#doc(int)} may thus not have the same value present as when
56     * this document was indexed.
57     *
58     * @see #setBoost(float)
59     */
60    public float getBoost() {
61      return boost;
62    }
63  
64    /**
65     * <p>Adds a field to a document.  Several fields may be added with
66     * the same name.  In this case, if the fields are indexed, their text is
67     * treated as though appended for the purposes of search.</p>
68     * <p> Note that add like the removeField(s) methods only makes sense 
69     * prior to adding a document to an index. These methods cannot
70     * be used to change the content of an existing index! In order to achieve this,
71     * a document has to be deleted from an index and a new changed version of that
72     * document has to be added.</p>
73     */
74    public final void add(Field field) {
75      fields.add(field);
76    }
77    
78    /**
79     * <p>Removes field with the specified name from the document.
80     * If multiple fields exist with this name, this method removes the first field that has been added.
81     * If there is no field with the specified name, the document remains unchanged.</p>
82     * <p> Note that the removeField(s) methods like the add method only make sense 
83     * prior to adding a document to an index. These methods cannot
84     * be used to change the content of an existing index! In order to achieve this,
85     * a document has to be deleted from an index and a new changed version of that
86     * document has to be added.</p>
87     */
88    public final void removeField(String   name) {
89      Iterator   it = fields.iterator();
90      while (it.hasNext()) {
91        Field field = (Field)it.next();
92        if (field.name().equals(name)) {
93          it.remove();
94          return;
95        }
96      }
97    }
98    
99    /**
100    * <p>Removes all fields with the given name from the document.
101    * If there is no field with the specified name, the document remains unchanged.</p>
102    * <p> Note that the removeField(s) methods like the add method only make sense 
103    * prior to adding a document to an index. These methods cannot
104    * be used to change the content of an existing index! In order to achieve this,
105    * a document has to be deleted from an index and a new changed version of that
106    * document has to be added.</p>
107    */
108   public final void removeFields(String   name) {
109     Iterator   it = fields.iterator();
110     while (it.hasNext()) {
111       Field field = (Field)it.next();
112       if (field.name().equals(name)) {
113         it.remove();
114       }
115     }
116   }
117 
118   /** Returns a field with the given name if any exist in this document, or
119    * null.  If multiple fields exists with this name, this method returns the
120    * first value added.
121    */
122   public final Field getField(String   name) {
123     for (int i = 0; i < fields.size(); i++) {
124       Field field = (Field)fields.get(i);
125       if (field.name().equals(name))
126     return field;
127     }
128     return null;
129   }
130 
131   /** Returns the string value of the field with the given name if any exist in
132    * this document, or null.  If multiple fields exist with this name, this
133    * method returns the first value added.
134    */
135   public final String   get(String   name) {
136     Field field = getField(name);
137     if (field != null)
138       return field.stringValue();
139     else
140       return null;
141   }
142 
143   /** Returns an Enumeration of all the fields in a document. */
144   public final Enumeration   fields() {
145     return ((Vector  )fields).elements();
146   }
147 
148   /**
149    * Returns an array of {@link Field}s with the given name.
150    * This method can return <code>null</code>.
151    *
152    * @param name the name of the field
153    * @return a <code>Field[]</code> array
154    */
155    public final Field[] getFields(String   name) {
156      List   result = new ArrayList  ();
157      for (int i = 0; i < fields.size(); i++) {
158        Field field = (Field)fields.get(i);
159        if (field.name().equals(name)) {
160          result.add(field);
161        }
162      }
163 
164      if (result.size() == 0)
165        return null;
166 
167      return (Field[])result.toArray(new Field[result.size()]);
168    }
169 
170   /**
171    * Returns an array of values of the field specified as the method parameter.
172    * This method can return <code>null</code>.
173    *
174    * @param name the name of the field
175    * @return a <code>String[]</code> of field values
176    */
177   public final String  [] getValues(String   name) {
178     Field[] namedFields = getFields(name);
179     if (namedFields == null)
180       return null;
181     String  [] values = new String  [namedFields.length];
182     for (int i = 0; i < namedFields.length; i++) {
183       values[i] = namedFields[i].stringValue();
184     }
185     return values;
186   }
187 
188   /** Prints the fields of a document for human consumption. */
189   public final String   toString() {
190     StringBuffer   buffer = new StringBuffer  ();
191     buffer.append("Document<");
192     for (int i = 0; i < fields.size(); i++) {
193       Field field = (Field)fields.get(i);
194       buffer.append(field.toString());
195       if (i != fields.size()-1)
196         buffer.append(" ");
197     }
198     buffer.append(">");
199     return buffer.toString();
200   }
201 }
202 
203
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