ExampleFileFilter


1   /*
2    * @(#)ExampleFileFilter.java   1.9 99/04/23
3    *
4    * Copyright (c) 1998, 1999 by Sun Microsystems, Inc. All Rights Reserved.
5    * 
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7    * modify and redistribute this software in source and binary code form,
8    * provided that i) this copyright notice and license appear on all copies of
9    * the software; and ii) Licensee does not utilize the software in a manner
10   * which is disparaging to Sun.
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29   */
30  package browser;
31  
32  import java.io.File  ;
33  import java.util.Hashtable  ;
34  import java.util.Enumeration  ;
35  import javax.swing.*;
36  import javax.swing.filechooser.*;
37  
38  /**
39   * A convenience implementation of FileFilter that filters out
40   * all files except for those type extensions that it knows about.
41   *
42   * Extensions are of the type ".foo", which is typically found on
43   * Windows and Unix boxes, but not on Macinthosh. Case is ignored.
44   *
45   * Example - create a new filter that filerts out all files
46   * but gif and jpg image files:
47   *
48   *     JFileChooser chooser = new JFileChooser();
49   *     ExampleFileFilter filter = new ExampleFileFilter(
50   *                   new String{"gif", "jpg"}, "JPEG & GIF Images")
51   *     chooser.addChoosableFileFilter(filter);
52   *     chooser.showOpenDialog(this);
53   *
54   * @version 1.9 04/23/99
55   * @author Jeff Dinkins
56   */
57  public class ExampleFileFilter extends FileFilter {
58  
59      private static String   TYPE_UNKNOWN = "Type Unknown";
60      private static String   HIDDEN_FILE = "Hidden File";
61  
62      private Hashtable   filters = null;
63      private String   description = null;
64      private String   fullDescription = null;
65      private boolean useExtensionsInDescription = true;
66  
67      /**
68       * Creates a file filter. If no filters are added, then all
69       * files are accepted.
70       *
71       * @see #addExtension
72       */
73      public ExampleFileFilter() {
74      this.filters = new Hashtable  ();
75      }
76  
77      /**
78       * Creates a file filter that accepts files with the given extension.
79       * Example: new ExampleFileFilter("jpg");
80       *
81       * @see #addExtension
82       */
83      public ExampleFileFilter(String   extension) {
84      this(extension,null);
85      }
86  
87      /**
88       * Creates a file filter that accepts the given file type.
89       * Example: new ExampleFileFilter("jpg", "JPEG Image Images");
90       *
91       * Note that the "." before the extension is not needed. If
92       * provided, it will be ignored.
93       *
94       * @see #addExtension
95       */
96      public ExampleFileFilter(String   extension, String   description) {
97      this();
98      if(extension!=null) addExtension(extension);
99      if(description!=null) setDescription(description);
100     }
101 
102     /**
103      * Creates a file filter from the given string array.
104      * Example: new ExampleFileFilter(String {"gif", "jpg"});
105      *
106      * Note that the "." before the extension is not needed adn
107      * will be ignored.
108      *
109      * @see #addExtension
110      */
111     public ExampleFileFilter(String  [] filters) {
112     this(filters, null);
113     }
114 
115     /**
116      * Creates a file filter from the given string array and description.
117      * Example: new ExampleFileFilter(String {"gif", "jpg"}, "Gif and JPG Images");
118      *
119      * Note that the "." before the extension is not needed and will be ignored.
120      *
121      * @see #addExtension
122      */
123     public ExampleFileFilter(String  [] filters, String   description) {
124     this();
125     for (int i = 0; i < filters.length; i++) {
126         // add filters one by one
127         addExtension(filters[i]);
128     }
129     if(description!=null) setDescription(description);
130     }
131 
132     /**
133      * Return true if this file should be shown in the directory pane,
134      * false if it shouldn't.
135      *
136      * Files that begin with "." are ignored.
137      *
138      * @see #getExtension
139      * @see FileFilter#accepts
140      */
141     public boolean accept(File   f) {
142     if(f != null) {
143         if(f.isDirectory()) {
144         return true;
145         }
146         String   extension = getExtension(f);
147         if(extension != null && filters.get(getExtension(f)) != null) {
148         return true;
149         };
150     }
151     return false;
152     }
153 
154     /**
155      * Return the extension portion of the file's name .
156      *
157      * @see #getExtension
158      * @see FileFilter#accept
159      */
160      public String   getExtension(File   f) {
161     if(f != null) {
162         String   filename = f.getName();
163         int i = filename.lastIndexOf('.');
164         if(i>0 && i<filename.length()-1) {
165         return filename.substring(i+1).toLowerCase();
166         };
167     }
168     return null;
169     }
170 
171     /**
172      * Adds a filetype "dot" extension to filter against.
173      *
174      * For example: the following code will create a filter that filters
175      * out all files except those that end in ".jpg" and ".tif":
176      *
177      *   ExampleFileFilter filter = new ExampleFileFilter();
178      *   filter.addExtension("jpg");
179      *   filter.addExtension("tif");
180      *
181      * Note that the "." before the extension is not needed and will be ignored.
182      */
183     public void addExtension(String   extension) {
184     if(filters == null) {
185         filters = new Hashtable  (5);
186     }
187     filters.put(extension.toLowerCase(), this);
188     fullDescription = null;
189     }
190 
191 
192     /**
193      * Returns the human readable description of this filter. For
194      * example: "JPEG and GIF Image Files (*.jpg, *.gif)"
195      *
196      * @see setDescription
197      * @see setExtensionListInDescription
198      * @see isExtensionListInDescription
199      * @see FileFilter#getDescription
200      */
201     public String   getDescription() {
202     if(fullDescription == null) {
203         if(description == null || isExtensionListInDescription()) {
204         fullDescription = description==null ? "(" : description + " (";
205         // build the description from the extension list
206         Enumeration   extensions = filters.keys();
207         if(extensions != null) {
208             fullDescription += "." + (String  ) extensions.nextElement();
209             while (extensions.hasMoreElements()) {
210             fullDescription += ", " + (String  ) extensions.nextElement();
211             }
212         }
213         fullDescription += ")";
214         } else {
215         fullDescription = description;
216         }
217     }
218     return fullDescription;
219     }
220 
221     /**
222      * Sets the human readable description of this filter. For
223      * example: filter.setDescription("Gif and JPG Images");
224      *
225      * @see setDescription
226      * @see setExtensionListInDescription
227      * @see isExtensionListInDescription
228      */
229     public void setDescription(String   description) {
230     this.description = description;
231     fullDescription = null;
232     }
233 
234     /**
235      * Determines whether the extension list (.jpg, .gif, etc) should
236      * show up in the human readable description.
237      *
238      * Only relevent if a description was provided in the constructor
239      * or using setDescription();
240      *
241      * @see getDescription
242      * @see setDescription
243      * @see isExtensionListInDescription
244      */
245     public void setExtensionListInDescription(boolean b) {
246     useExtensionsInDescription = b;
247     fullDescription = null;
248     }
249 
250     /**
251      * Returns whether the extension list (.jpg, .gif, etc) should
252      * show up in the human readable description.
253      *
254      * Only relevent if a description was provided in the constructor
255      * or using setDescription();
256      *
257      * @see getDescription
258      * @see setDescription
259      * @see setExtensionListInDescription
260      */
261     public boolean isExtensionListInDescription() {
262     return useExtensionsInDescription;
263     }
264 }
265
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