Swing-JFileChooser的使用

JFileChooser文件选择器是Swing中经常用到的一个控件。它的使用主要包含以下几个参数：

1.当前路径。也就是它第一次打开时所在的路径，许多软件喜欢设置为桌面。

2.文件过滤器。通过设置文件过滤器，只有特定类型的文件是可见的，比如文本，音频，等。

3.选择模式。包含三种情况：仅文件, 仅目录, 文件或目录。

4.是否允许多选。

JFileChooser的参数当然不止以上4种，它还有很多高级选项，比如你可以对文件的显示图标进行定制等，由于不经常用，这里不再介绍。

有2个地方要注意：

1.文件过滤器建议使用FileNameExtensionFilter，它是FileFilter的子类，以非常方便的方法实现了过滤器。用法见代码。

2.getSelectedFiles()方法，它只在isMultiSelectionEnable()方法返回true是有效。也就是说，如果你不允许多选，则只能使用getSelectedFile()方法，否则只能得到一个空的文件列表。

下面通过一个demo来展示它的基本用法。

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package org.javacore.swing.JfileChooser;

import java.io.File;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.filechooser.FileNameExtensionFilter;
import javax.swing.filechooser.FileSystemView;

/**
 *
 * @author pzy
 */
public class JFileChooserFrame extends javax.swing.JFrame {

    /**
     * Creates new form JFileChooserFrame
     */
    public JFileChooserFrame() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        fileFilterisBG = new javax.swing.ButtonGroup();
        isMultiSelectBG = new javax.swing.ButtonGroup();
        jPanel1 = new javax.swing.JPanel();
        text_rb = new javax.swing.JRadioButton();
        video_rb = new javax.swing.JRadioButton();
        audio_rb = new javax.swing.JRadioButton();
        all_rb = new javax.swing.JRadioButton();
        jPanel2 = new javax.swing.JPanel();
        jComboBox1 = new javax.swing.JComboBox();
        multiSelect_rb = new javax.swing.JRadioButton();
        singleSelect_rb = new javax.swing.JRadioButton();
        jPanel3 = new javax.swing.JPanel();
        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setLocationByPlatform(true);

        jPanel1.setBorder(javax.swing.BorderFactory.createTitledBorder("文件类型"));

        fileFilterisBG.add(text_rb);
        text_rb.setText("文本");

        fileFilterisBG.add(video_rb);
        video_rb.setText("视频");

        fileFilterisBG.add(audio_rb);
        audio_rb.setText("音频");

        fileFilterisBG.add(all_rb);
        all_rb.setSelected(true);
        all_rb.setText("所有");

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(text_rb)
                .addGap(29, 29, 29)
                .addComponent(video_rb)
                .addGap(35, 35, 35)
                .addComponent(audio_rb)
                .addGap(39, 39, 39)
                .addComponent(all_rb)
                .addGap(32, 32, 32))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(video_rb)
                    .addComponent(text_rb)
                    .addComponent(audio_rb)
                    .addComponent(all_rb))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );

        jPanel2.setBorder(javax.swing.BorderFactory.createTitledBorder("选择模式"));

        jComboBox1.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "仅文件", "仅目录", "文件或目录" }));
        jComboBox1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jComboBox1ActionPerformed(evt);
            }
        });

        isMultiSelectBG.add(multiSelect_rb);
        multiSelect_rb.setText("可多选");

        isMultiSelectBG.add(singleSelect_rb);
        singleSelect_rb.setSelected(true);
        singleSelect_rb.setText("不可多选");

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 144, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(multiSelect_rb, javax.swing.GroupLayout.PREFERRED_SIZE, 82, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(singleSelect_rb, javax.swing.GroupLayout.PREFERRED_SIZE, 82, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(14, Short.MAX_VALUE))
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(multiSelect_rb)
                    .addComponent(singleSelect_rb))
                .addContainerGap(16, Short.MAX_VALUE))
        );

        jButton1.setText("开始");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
        jPanel3.setLayout(jPanel3Layout);
        jPanel3Layout.setHorizontalGroup(
            jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel3Layout.createSequentialGroup()
                .addGap(117, 117, 117)
                .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 139, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        jPanel3Layout.setVerticalGroup(
            jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel3Layout.createSequentialGroup()
                .addGap(26, 26, 26)
                .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 32, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(19, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addGap(84, 84, 84)))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(8, 8, 8)
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18)
                .addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

    private void jComboBox1ActionPerformed(java.awt.event.ActionEvent evt) {                                           
        // TODO add your handling code here:
        String itemString = jComboBox1.getSelectedItem().toString();
        if ("仅文件".equals(itemString)) {
            fileSelectionMode = JFileChooser.FILES_ONLY;
        } else if ("仅目录".equals(itemString)) {
            fileSelectionMode = JFileChooser.DIRECTORIES_ONLY;
        } else if ("文件或目录".equals(itemString)) {
            fileSelectionMode = JFileChooser.FILES_AND_DIRECTORIES;
        }
    }                                          

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        fileChooser = new JFileChooser();
        //初始化当前路径
        FileSystemView fsv = FileSystemView.getFileSystemView();
        File homeFile =fsv.getHomeDirectory();    //这便是读取桌面路径的方法了
        fileChooser.setCurrentDirectory(homeFile);
        
        //初始化文件过滤器
        if (text_rb.isSelected()) {
            filter = new FileNameExtensionFilter("文本文件", "log", "txt");
            fileChooser.setFileFilter(filter);
        }
        if (video_rb.isSelected()) {
            filter = new FileNameExtensionFilter("视频文件", "mp4", "mkv");
            fileChooser.setFileFilter(filter);
        }
        if (audio_rb.isSelected()) {
            filter = new FileNameExtensionFilter("音频文件", "mp3", "wma");
            fileChooser.setFileFilter(filter);
        }
        //初始化选择模式
        fileChooser.setFileSelectionMode(fileSelectionMode);
        //是否允许多选
        if (multiSelect_rb.isSelected()) {
            fileChooser.setMultiSelectionEnabled(true);
        }
        else if(singleSelect_rb.isSelected()) {
            fileChooser.setMultiSelectionEnabled(false);
        }
        
        //打开文件选择器
        int i = fileChooser.showDialog(this, "选择");
        if(i == JFileChooser.APPROVE_OPTION){
            StringBuilder sb;
            if(fileChooser.isMultiSelectionEnabled()){
            sb = new StringBuilder("您选择了以下文件：");
            
            File [] files = fileChooser.getSelectedFiles();
            for (File file : files) {
                sb.append("
");
                sb.append(file.getName());
            }
            }
            else{
                File file = fileChooser.getSelectedFile();
                sb = new StringBuilder("您选择的文件是：");
                 sb.append("
");
                sb.append(file.getName());
            }
            JOptionPane.showMessageDialog(this, sb);
        }
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(JFileChooserFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(JFileChooserFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(JFileChooserFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(JFileChooserFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new JFileChooserFrame().setVisible(true);
            }
        });
    }

    private JFileChooser fileChooser;
    private FileNameExtensionFilter filter;
    private int fileSelectionMode = JFileChooser.FILES_ONLY;

    // Variables declaration - do not modify                     
    private javax.swing.JRadioButton all_rb;
    private javax.swing.JRadioButton audio_rb;
    private javax.swing.ButtonGroup fileFilterisBG;
    private javax.swing.ButtonGroup isMultiSelectBG;
    private javax.swing.JButton jButton1;
    private javax.swing.JComboBox jComboBox1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JPanel jPanel3;
    private javax.swing.JRadioButton multiSelect_rb;
    private javax.swing.JRadioButton singleSelect_rb;
    private javax.swing.JRadioButton text_rb;
    private javax.swing.JRadioButton video_rb;
    // End of variables declaration                   
}

运行效果如下：