JFileChooser添加文件过滤

    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());
    }

// Note: source for ExampleFileFilter can be found in FileChooserDemo,
// under the demo/jfc directory in the JDK.

/*
 * %W% %E%
 *
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.swing.filechooser;

import java.io.File;

/**
 * <code>FileFilter</code> is an abstract class used by {@code JFileChooser}
 * for filtering the set of files shown to the user. See 
 * {@code FileNameExtensionFilter} for an implementation that filters using
 * the file name extension.
 * <p>
 * A <code>FileFilter</code> 
 * can be set on a <code>JFileChooser</code> to
 * keep unwanted files from appearing in the directory listing.
 * For an example implementation of a simple file filter, see
 * <code><i>yourJDK</i>/demo/jfc/FileChooserDemo/ExampleFileFilter.java</code>.
 * For more information and examples see 
 * <a href="http://t.zoukankan.com/http://java.sun.com/docs/books/tutorial/uiswing/components/filechooser.html">How to Use File Choosers</a>,
 * a section in <em>The Java Tutorial</em>.
 *
 * @see FileNameExtensionFilter
 * @see javax.swing.JFileChooser#setFileFilter
 * @see javax.swing.JFileChooser#addChoosableFileFilter
 *
 * @version %I% %G%
 * @author Jeff Dinkins
 */
public abstract class FileFilter {
    /**
     * Whether the given file is accepted by this filter.
     */
    public abstract boolean accept(File f);

    /**
     * The description of this filter. For example: "JPG and GIF Images"
     * @see FileView#getName
     */
    public abstract String getDescription();
}

public class MyFileFilter extends FileFilter {
        public boolean accept(File f) {
            if(f.getName().contains(".jpg") || f.isDirectory()){
                return true;
            }
            return false;
        }
        public String getDescription() {
            return "jpg文件";
        }
}

import java.io.File;
import java.util.Enumeration;
import java.util.Hashtable;

import javax.swing.filechooser.FileFilter;

public class MyFileFilter 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 MyFileFilter() {
        this.filters = new Hashtable();
    }

    public MyFileFilter(String extension) {
        this(extension, null);
    }

    public MyFileFilter(String extension, String description) {
        this();
        if (extension != null)
            addExtension(extension);
        if (description != null)
            setDescription(description);
    }

    public MyFileFilter(String[] filters) {
        this(filters, null);
    }

    public MyFileFilter(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;
    }

}