DefaultFileFilter


1   /*
2    * @(#)DefaultFileFilter.java    1.12 01/12/03
3    *
4    * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package org.pdfbox.util;
8   
9   import java.io.File  ;
10  import java.util.Hashtable  ;
11  import java.util.Enumeration  ;
12  //import javax.swing.*;
13  import javax.swing.filechooser.FileFilter  ;
14  
15  /**
16   * A convenience implementation of FileFilter that filters out
17   * all files except for those type extensions that it knows about.
18   *
19   * Extensions are of the type ".foo", which is typically found on
20   * Windows and Unix boxes, but not on Macinthosh. Case is ignored.
21   *
22   * Example - create a new filter that filerts out all files
23   * but gif and jpg image files:
24   *
25   *     JFileChooser chooser = new JFileChooser();
26   *     DefaultFileFilter filter = new DefaultFileFilter(
27   *                   new String{"gif", "jpg"}, "JPEG & GIF Images")
28   *     chooser.addChoosableFileFilter(filter);
29   *     chooser.showOpenDialog(this);
30   *
31   * @version $Revision: 1.2 $
32   * @author Jeff Dinkins
33   */
34  public class DefaultFileFilter extends FileFilter  
35  {
36  
37      private static final String   TYPE_UNKNOWN = "Type Unknown";
38      private static final String   HIDDEN_FILE = "Hidden File";
39  
40      private Hashtable   filters = null;
41      private String   description = null;
42      private String   fullDescription = null;
43      private boolean useExtensionsInDescription = true;
44  
45      /**
46       * Creates a file filter. If no filters are added, then all
47       * files are accepted.
48       *
49       * @see #addExtension
50       */
51      public DefaultFileFilter()
52      {
53          this.filters = new Hashtable  ();
54      }
55  
56      /**
57       * Creates a file filter that accepts files with the given extension.
58       * Example: new DefaultFileFilter("jpg");
59       *
60       * @see #addExtension
61       */
62      public DefaultFileFilter(String   extension)
63      {
64          this(extension,null);
65      }
66  
67      /**
68       * Creates a file filter that accepts the given file type.
69       * Example: new DefaultFileFilter("jpg", "JPEG Image Images");
70       *
71       * Note that the "." before the extension is not needed. If
72       * provided, it will be ignored.
73       *
74       * @see #addExtension
75       */
76      public DefaultFileFilter(String   extension, String   desc)
77      {
78          this();
79          if(extension!=null)
80          {
81              addExtension(extension);
82          }
83          if(desc!=null)
84          {
85              setDescription(desc);
86          }
87      }
88  
89      /**
90       * Creates a file filter from the given string array.
91       * Example: new DefaultFileFilter(String {"gif", "jpg"});
92       *
93       * Note that the "." before the extension is not needed adn
94       * will be ignored.
95       *
96       * @see #addExtension
97       */
98      public DefaultFileFilter(String  [] filterArray)
99      {
100         this(filterArray, null);
101     }
102 
103     /**
104      * Creates a file filter from the given string array and description.
105      * Example: new DefaultFileFilter(String {"gif", "jpg"}, "Gif and JPG Images");
106      *
107      * Note that the "." before the extension is not needed and will be ignored.
108      *
109      * @see #addExtension
110      */
111     public DefaultFileFilter(String  [] filterArray, String   desc)
112     {
113         this();
114         for (int i = 0; i < filterArray.length; i++)
115         {
116             // add filters one by one
117             addExtension(filterArray[i]);
118         }
119         if(desc!=null)
120         {
121             setDescription(desc);
122         }
123     }
124 
125     /**
126      * Files that begin with "." are ignored.
127      *
128      * @param f The file to accept.
129      * @return true if this file should be shown in the directory pane, false if it shouldn't.
130      * @see #getExtension
131      * @see FileFilter#accepts
132      */
133     public boolean accept(File   f)
134     {
135         if(f != null)
136         {
137             if(f.isDirectory())
138             {
139                 return true;
140             }
141             String   extension = getExtension(f);
142             if(extension != null && filters.get(getExtension(f)) != null)
143             {
144                 return true;
145             }
146         }
147         return false;
148     }
149 
150     /**
151      * Return the extension portion of the file's name .
152      *
153      * @param f The file to get the extension of.
154      * @return The extension of a file.
155      * @see #getExtension
156      * @see FileFilter#accept
157      */
158      public String   getExtension(File   f)
159      {
160         if(f != null)
161         {
162             String   filename = f.getName();
163             int i = filename.lastIndexOf('.');
164             if(i>0 && i<filename.length()-1)
165             {
166                 return filename.substring(i+1).toLowerCase();
167             }
168         }
169         return null;
170     }
171 
172     /**
173      * Adds a filetype "dot" extension to filter against.
174      *
175      * For example: the following code will create a filter that filters
176      * out all files except those that end in ".jpg" and ".tif":
177      *
178      *   DefaultFileFilter filter = new DefaultFileFilter();
179      *   filter.addExtension("jpg");
180      *   filter.addExtension("tif");
181      *
182      * Note that the "." before the extension is not needed and will be ignored.
183      *
184      * @param extension The new extension to add.
185      */
186     public void addExtension(String   extension)
187     {
188         if(filters == null)
189         {
190             filters = new Hashtable  (5);
191         }
192         filters.put(extension.toLowerCase(), this);
193         fullDescription = null;
194     }
195 
196 
197     /**
198      * Returns the human readable description of this filter. For
199      * example: "JPEG and GIF Image Files (*.jpg, *.gif)"
200      *
201      * @see setDescription
202      * @see setExtensionListInDescription
203      * @see isExtensionListInDescription
204      * @see FileFilter#getDescription
205      *
206      * @return The human readable description of this filter.
207      */
208     public String   getDescription()
209     {
210         if(fullDescription == null)
211         {
212             if(description == null || isExtensionListInDescription())
213             {
214                 fullDescription = description==null ? "(" : description + " (";
215                 // build the description from the extension list
216                 Enumeration   extensions = filters.keys();
217                 if(extensions != null)
218                 {
219                     fullDescription += "." + (String  ) extensions.nextElement();
220                     while (extensions.hasMoreElements())
221                     {
222                         fullDescription += ", ." + (String  ) extensions.nextElement();
223                     }
224                 }
225                 fullDescription += ")";
226             }
227             else
228             {
229                 fullDescription = description;
230             }
231         }
232         return fullDescription;
233     }
234 
235     /**
236      * Sets the human readable description of this filter. For
237      * example: filter.setDescription("Gif and JPG Images");
238      *
239      * @param desc the new description for the file.
240      * @see setDescription
241      * @see setExtensionListInDescription
242      * @see isExtensionListInDescription
243      */
244     public void setDescription(String   desc)
245     {
246         description = desc;
247         fullDescription = null;
248     }
249 
250     /**
251      * Determines 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      *
258      * @param b Tell if the extionsion shoud show up in human readable description.
259      * @see getDescription
260      * @see setDescription
261      * @see isExtensionListInDescription
262      */
263     public void setExtensionListInDescription(boolean b)
264     {
265         useExtensionsInDescription = b;
266         fullDescription = null;
267     }
268 
269     /**
270      * @return whether the extension list (.jpg, .gif, etc) should
271      * show up in the human readable description.
272      *
273      * Only relevent if a description was provided in the constructor
274      * or using setDescription();
275      *
276      *
277      * @see getDescription
278      * @see setDescription
279      * @see setExtensionListInDescription
280      */
281     public boolean isExtensionListInDescription()
282     {
283         return useExtensionsInDescription;
284     }
285 }
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