JFileChooser：ExampleFileFilter.java 类文件
http://whisperlin.blog.163.com/blog/static/605237102008310113243310/
今天在写打开文件对话框的代码时，想对文件类型进行限制，在JDK帮助文档中,提供了如下方法：
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Java代码 JFileChooser chooser = new JFileChooser(); // Note: source for ExampleFileFilter can be found in FileChooserDemo, // under the demo/jfc directory in the JDK. ExampleFileFilter filter = new ExampleFileFilter(); filter.addExtension("jpg"); filter.addExtension("gif"); filter.setDescription("JPG & GIF Images"); chooser.setFileFilter(filter); int returnVal = chooser.showOpenDialog(parent); if(returnVal == JFileChooser.APPROVE_OPTION) { System.out.println("You chose to open this file: " + chooser.getSelectedFile().getName()); } |
在其中用到ExampleFileFilter这个类，继承了FileFilter这个接口，它放在j2sdk1.4.2_16\demo\jfc\FileChooserDemo\src 中，我用的是jdk1.6版本，偏偏没有这个文件，郁闷了半天，无奈装了遍j1.4,现在问题解决了，将代码提取出来如下：
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Java代码 import java.io.File; import java.util.Hashtable; import java.util.Enumeration; import javax.swing.*; import javax.swing.filechooser.*; public class ExampleFileFilter 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; public ExampleFileFilter() { this.filters = new Hashtable(); } public ExampleFileFilter(String extension) { this(extension,null); } public ExampleFileFilter(String extension, String description) { this(); if(extension!=null) addExtension(extension); if(description!=null) setDescription(description); } public ExampleFileFilter(String[] filters) { this(filters, null); } public ExampleFileFilter(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); } 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; } 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; } public void addExtension(String extension) { if(filters == null) { filters = new Hashtable(5); } filters.put(extension.toLowerCase(), this); fullDescription = null; } 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; } public void setDescription(String description) { this.description = description; fullDescription = null; } public void setExtensionListInDescription(boolean b) { useExtensionsInDescription = b; fullDescription = null; } public boolean isExtensionListInDescription() { return useExtensionsInDescription; } } |
