|
/Users/lyon/j4p/src/gui/ExtensionFileFilter.java
|
1 package gui;
2
3 import javax.swing.filechooser.FileFilter;
4 import java.io.File;
5 import java.util.Enumeration;
6 import java.util.Hashtable;
7
8 /**
9 * <b>Sun's FileFilter example, renamed</b>
10 * <br>
11 * A convenience implementation of FileFilter that filters out
12 * all files except for those type extensions that it knows about.
13 * <p>
14 * Extensions are of the type ".foo", which is typically found on
15 * Windows and Unix boxes, but not on Macintosh. Case is ignored.
16 * <br>
17 * Example - create a new filter that filters out all files
18 * but gif and jpg image files:
19 * <br>
20 * <pre>
21 * JFileChooser chooser = new JFileChooser();
22 * ExtensionFileFilter filter = new ExtensionFileFilter(
23 * new String{"gif", "jpg"}, "JPEG & GIF Images")
24 * chooser.addChoosableFileFilter(filter);
25 * chooser.showOpenDialog(this);
26 * </pre>
27 * @version 1.1 10/14/99
28 * @author Jeff Dinkins
29 */
30 public class ExtensionFileFilter extends FileFilter {
31
32 private static String TYPE_UNKNOWN = "Type Unknown";
33 private static String HIDDEN_FILE = "Hidden File";
34
35 private Hashtable filters = null;
36 private String description = null;
37 private String fullDescription = null;
38 private boolean useExtensionsInDescription = true;
39
40 /**
41 * Creates a file filter. If no filters are added, then all
42 * files are accepted.
43 *
44 */
45 public ExtensionFileFilter() {
46 this.filters = new Hashtable();
47 }
48
49 /**
50 * Creates a file filter that accepts files with the given extension.
51 * <br>
52 * Example: <tt>new ExtensionFileFilter("jpg");</tt>
53 *
54 */
55 public ExtensionFileFilter(String extension) {
56 this(extension, null);
57 }
58
59 /**
60 * Creates a file filter that accepts the given file type.
61 * Example: <tt>new ExtensionFileFilter("jpg", "JPEG Image Images");</tt>
62 * <br>
63 * Note that the "." before the extension is not needed. If
64 * provided, it will be ignored.
65 *
66 */
67 public ExtensionFileFilter(String extension, String description) {
68 this();
69 if (extension != null) addExtension(extension);
70 if (description != null) setDescription(description);
71 }
72
73 /**
74 * Creates a file filter from the given string array.
75 * <br>
76 * Example: <tt>new ExtensionFileFilter(String {"gif", "jpg"});</tt>
77 * <br>
78 * Note that the "." before the extension is not needed adn
79 * will be ignored.
80 *
81 */
82 public ExtensionFileFilter(String[] filters) {
83 this(filters, null);
84 }
85
86 /**
87 * Creates a file filter from the given string array and description.
88 * <br>
89 * Example: <tt>new ExtensionFileFilter(String {"gif", "jpg"}, "Gif and JPG Images");</tt>
90 * <br>
91 * Note that the "." before the extension is not needed and will be ignored.
92 *
93 */
94 public ExtensionFileFilter(String[] filters, String description) {
95 this();
96 for (int i = 0; i < filters.length; i++) {
97 // add filters one by one
98 addExtension(filters[i]);
99 }
100 if (description != null) setDescription(description);
101 }
102
103 /**
104 * Return true if this file should be shown in the directory pane,
105 * false if it shouldn't.
106 * <br>
107 * Files that begin with "." are ignored.
108 *
109 */
110 public boolean accept(File f) {
111 if (f != null) {
112 if (f.isDirectory()) {
113 return true;
114 }
115 String extension = getExtension(f);
116 if (extension != null && filters.get(getExtension(f)) != null) {
117 return true;
118 }
119 ;
120 }
121 return false;
122 }
123
124 /**
125 * Return the extension portion of the file's name .
126 *
127 */
128 public String getExtension(File f) {
129 if (f != null) {
130 String filename = f.getName();
131 int i = filename.lastIndexOf('.');
132 if (i > 0 && i < filename.length() - 1) {
133 return filename.substring(i + 1).toLowerCase();
134 }
135 ;
136 }
137 return null;
138 }
139
140 /**
141 * Adds a filetype "dot" extension to filter against.
142 * <br>
143 * For example: the following code will create a filter that filters
144 * out all files except those that end in ".jpg" and ".tif":
145 * <br>
146 * <pre>
147 * ExtensionFileFilter filter = new ExtensionFileFilter();
148 * filter.addExtension("jpg");
149 * filter.addExtension("tif");
150 * </pre>
151 * Note that the "." before the extension is not needed and will be ignored.
152 */
153 public void addExtension(String extension) {
154 if (filters == null) {
155 filters = new Hashtable(5);
156 }
157 filters.put(extension.toLowerCase(), this);
158 fullDescription = null;
159 }
160
161
162 /**
163 * Returns the human readable description of this filter. For
164 * example: "JPEG and GIF Image Files (*.jpg, *.gif)"
165 *
166 */
167 public String getDescription() {
168 if (fullDescription == null) {
169 if (description == null || isExtensionListInDescription()) {
170 fullDescription = description == null ? "(" : description + " (";
171 // build the description from the extension list
172 Enumeration extensions = filters.keys();
173 if (extensions != null) {
174 fullDescription += "." + (String) extensions.nextElement();
175 while (extensions.hasMoreElements()) {
176 fullDescription += ", " + (String) extensions.nextElement();
177 }
178 }
179 fullDescription += ")";
180 } else {
181 fullDescription = description;
182 }
183 }
184 return fullDescription;
185 }
186
187 /**
188 * Sets the human readable description of this filter. For
189 * example: filter.setDescription("Gif and JPG Images");
190 *
191 */
192 public void setDescription(String description) {
193 this.description = description;
194 fullDescription = null;
195 }
196
197 /**
198 * Determines whether the extension list (.jpg, .gif, etc) should
199 * show up in the human readable description.
200 * <br>
201 * Only relevant if a description was provided in the constructor
202 * or using setDescription();
203 *
204 */
205 public void setExtensionListInDescription(boolean b) {
206 useExtensionsInDescription = b;
207 fullDescription = null;
208 }
209
210 /**
211 * Returns whether the extension list (.jpg, .gif, etc) should
212 * show up in the human readable description.
213 * <br>
214 * Only relevant if a description was provided in the constructor
215 * or using setDescription();
216 *
217 */
218 public boolean isExtensionListInDescription() {
219 return useExtensionsInDescription;
220 }
221 }