FileDialog使用方法:

FileDialog fd=new FileDialog(new Frame(),"测试",FileDialog.LOAD);
FilenameFilter ff=new FilenameFilter(){
   public boolean accept(File dir, String name) {
    if (name.endsWith("jpg")){
     return true;
    }
    return false;
   }
  };
  fd.setFilenameFilter(ff);
fd.setVisible(true);
System.out.println(fd.getDirectory()+fd.getFile());

但在Windows中FileDialog + FilenameFilter无法正常工作, jdoc的原注释为:Filename filters do not function in Sun's reference implementation for Microsoft Windows.

2.FileDialog + FilenameFilter可以用JFileChooser + javax.swing.filechooser.FileFilter 来代替，jdoc中的例子如下：

    JFileChooser chooser = new JFileChooser();
    // Note: source for ExampleFileFilter can be found in FileChooserDemo,
    // under the demo/jfc directory in the Java 2 SDK, Standard Edition.
    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());
    }

转应用实例：
    JFileChooser filechooser = new JFileChooser();//创建文件选择器
    filechooser.setCurrentDirectory(new File("."));//设置当前目录
    filechooser.setAcceptAllFileFilterUsed(false);
    //显示所有文件
    filechooser.addChoosableFileFilter(new javax.swing.filechooser.FileFilter() {
      public boolean accept(File f) {
        return true;
      }
      public String getDescription() {
        return "所有文件(*.*)";
      }
    });
    //显示JAVA源文件
    filechooser.setFileFilter(new javax.swing.filechooser.FileFilter() {
      public boolean accept(File f) { //设定可用的文件的后缀名
        if(f.getName().endsWith(".java")||f.isDirectory()){
          return true;
        }
        return false;
      }
      public String getDescription() {
        return "JAVA源程序(*.java)";
      }
    });