ExtensionFileFilter.java |
package gui; import java.io.File; import java.util.Hashtable; import java.util.Enumeration; import javax.swing.*; import javax.swing.filechooser.*; /** * <b>Sun's FileFilter example, renamed</b> * <br> * A convenience implementation of FileFilter that filters out * all files except for those type extensions that it knows about. * <p> * Extensions are of the type ".foo", which is typically found on * Windows and Unix boxes, but not on Macintosh. Case is ignored. * <br> * Example - create a new filter that filters out all files * but gif and jpg image files: * <br> * <pre> * JFileChooser chooser = new JFileChooser(); * ExtensionFileFilter filter = new ExtensionFileFilter( * new String{"gif", "jpg"}, "JPEG & GIF Images") * chooser.addChoosableFileFilter(filter); * chooser.showOpenDialog(this); * </pre> * @version 1.1 10/14/99 * @author Jeff Dinkins */ public class ExtensionFileFilter extends FileFilter { private static String TYPE_UNKNOWN = "Type Unknown"; private static String HIDDEN_FILE = "Hidden File"; private Hashtable filters = null; private String description = null; private String fullDescription = null; private boolean useExtensionsInDescription = true; /** * Creates a file filter. If no filters are added, then all * files are accepted. * */ public ExtensionFileFilter() { this.filters = new Hashtable(); } /** * Creates a file filter that accepts files with the given extension. * <br> * Example: <tt>new ExtensionFileFilter("jpg");</tt> * */ public ExtensionFileFilter(String extension) { this(extension,null); } /** * Creates a file filter that accepts the given file type. * Example: <tt>new ExtensionFileFilter("jpg", "JPEG Image Images");</tt> * <br> * Note that the "." before the extension is not needed. If * provided, it will be ignored. * */ public ExtensionFileFilter(String extension, String description) { this(); if(extension!=null) addExtension(extension); if(description!=null) setDescription(description); } /** * Creates a file filter from the given string array. * <br> * Example: <tt>new ExtensionFileFilter(String {"gif", "jpg"});</tt> * <br> * Note that the "." before the extension is not needed adn * will be ignored. * */ public ExtensionFileFilter(String[] filters) { this(filters, null); } /** * Creates a file filter from the given string array and description. * <br> * Example: <tt>new ExtensionFileFilter(String {"gif", "jpg"}, "Gif and JPG Images");</tt> * <br> * Note that the "." before the extension is not needed and will be ignored. * */ public ExtensionFileFilter(String[] filters, String description) { this(); for (int i = 0; i < filters.length; i++) { // add filters one by one addExtension(filters[i]); } if(description!=null) setDescription(description); } /** * Return true if this file should be shown in the directory pane, * false if it shouldn't. * <br> * Files that begin with "." are ignored. * */ public boolean accept(File f) { if(f != null) { if(f.isDirectory()) { return true; } String extension = getExtension(f); if(extension != null && filters.get(getExtension(f)) != null) { return true; }; } return false; } /** * Return the extension portion of the file's name . * */ public String getExtension(File f) { if(f != null) { String filename = f.getName(); int i = filename.lastIndexOf('.'); if(i>0 && i<filename.length()-1) { return filename.substring(i+1).toLowerCase(); }; } return null; } /** * Adds a filetype "dot" extension to filter against. * <br> * For example: the following code will create a filter that filters * out all files except those that end in ".jpg" and ".tif": * <br> * <pre> * ExtensionFileFilter filter = new ExtensionFileFilter(); * filter.addExtension("jpg"); * filter.addExtension("tif"); * </pre> * Note that the "." before the extension is not needed and will be ignored. */ public void addExtension(String extension) { if(filters == null) { filters = new Hashtable(5); } filters.put(extension.toLowerCase(), this); fullDescription = null; } /** * Returns the human readable description of this filter. For * example: "JPEG and GIF Image Files (*.jpg, *.gif)" * */ public String getDescription() { if(fullDescription == null) { if(description == null || isExtensionListInDescription()) { fullDescription = description==null ? "(" : description + " ("; // build the description from the extension list Enumeration extensions = filters.keys(); if(extensions != null) { fullDescription += "." + (String) extensions.nextElement(); while (extensions.hasMoreElements()) { fullDescription += ", " + (String) extensions.nextElement(); } } fullDescription += ")"; } else { fullDescription = description; } } return fullDescription; } /** * Sets the human readable description of this filter. For * example: filter.setDescription("Gif and JPG Images"); * */ public void setDescription(String description) { this.description = description; fullDescription = null; } /** * Determines whether the extension list (.jpg, .gif, etc) should * show up in the human readable description. * <br> * Only relevant if a description was provided in the constructor * or using setDescription(); * */ public void setExtensionListInDescription(boolean b) { useExtensionsInDescription = b; fullDescription = null; } /** * Returns whether the extension list (.jpg, .gif, etc) should * show up in the human readable description. * <br> * Only relevant if a description was provided in the constructor * or using setDescription(); * */ public boolean isExtensionListInDescription() { return useExtensionsInDescription; } }