最近学习Swing，写了个文件选种器，可以浏览图片哦。很粗糙，不过很有意思。
首先是一个JPanel的继承类。用来设置文件选择器JFileChooser
1
package book.swing.jfilechooser;
2
3import javax.swing.*;
4import javax.swing.border.BevelBorder;
5import java.io.*;
6import java.awt.*;
7import java.awt.event.*;
8import java.beans.PropertyChangeEvent;
9import java.beans.PropertyChangeListener;
10
11
public class ImageAccessory extends JPanel implements PropertyChangeListener{
12
13 private Icon icon;
14 private JLabel imageName;
15 private JLabel imageLabel;
16 private JScrollPane scrollpane;
17
public ImageAccessory(){
18 setLayout(new BorderLayout());
19 icon = new ImageIcon("/home/madic/adapter.png");
20 imageLabel = new JLabel(icon);
21 // imagePanel.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED));
22 imageLabel.setBorder(BorderFactory.createLineBorder(Color.green));
23 scrollpane = new JScrollPane(imageLabel);
24 add(imageName = new JLabel("imagename"), BorderLayout.NORTH);
25 add(scrollpane, BorderLayout.CENTER);
26
}
27 public void propertyChange(PropertyChangeEvent pe){
28 if(pe.getPropertyName().equals(
29 JFileChooser.SELECTED_FILE_CHANGED_PROPERTY)){
30 File f = (File)pe.getNewValue();
31 if(f==null){
32 return;
33 }
34 if(!f.isDirectory()){
35 System.out.println(f.getAbsolutePath());
36 imageName.setText(f.getName());
37 ImageIcon ii = new ImageIcon(f.getAbsolutePath());
38 Image image = ii.getImage().getScaledInstance(200, 300, Image.SCALE_DEFAULT);
39 ii.setImage(image);
40 icon = ii;
41 imageLabel.setIcon(icon);
42 imageLabel.updateUI();
43 this.updateUI();
44 }
45 }
46 }
47
48
}
49
package book.swing.jfilechooser;2
3
import javax.swing.*;4
import javax.swing.border.BevelBorder;5
import java.io.*;6
import java.awt.*;7
import java.awt.event.*;8
import java.beans.PropertyChangeEvent;9
import java.beans.PropertyChangeListener;10
11
public class ImageAccessory extends JPanel implements PropertyChangeListener{
12
13
private Icon icon;14
private JLabel imageName;15
private JLabel imageLabel;16
private JScrollPane scrollpane;17
public ImageAccessory(){
18
setLayout(new BorderLayout());19
icon = new ImageIcon("/home/madic/adapter.png");20
imageLabel = new JLabel(icon);21
// imagePanel.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED));22
imageLabel.setBorder(BorderFactory.createLineBorder(Color.green));23
scrollpane = new JScrollPane(imageLabel);24
add(imageName = new JLabel("imagename"), BorderLayout.NORTH);25
add(scrollpane, BorderLayout.CENTER);26
}27
public void propertyChange(PropertyChangeEvent pe){28
if(pe.getPropertyName().equals(29
JFileChooser.SELECTED_FILE_CHANGED_PROPERTY)){30
File f = (File)pe.getNewValue();31
if(f==null){32
return;33
}34
if(!f.isDirectory()){35
System.out.println(f.getAbsolutePath());36
imageName.setText(f.getName());37
ImageIcon ii = new ImageIcon(f.getAbsolutePath());38
Image image = ii.getImage().getScaledInstance(200, 300, Image.SCALE_DEFAULT);39
ii.setImage(image);40
icon = ii;41
imageLabel.setIcon(icon);42
imageLabel.updateUI();43
this.updateUI();44
}45
}46
}47
48
}49
下面就是一个演示JFileChooser的例子了：
package book.swing.jfilechooser;import javax.swing.*;import java.awt.*;import java.awt.event.*;public class ImageFileChooser extends JFrame{ private JButton open; private JFrame parent; private final JLabel statusbar; public ImageFileChooser(){ super("ImageFileChooser"); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); parent = this; statusbar = new JLabel( "Output of your selection will go here"); Container c = getContentPane(); c.setLayout(new FlowLayout()); open = new JButton("Open"); open.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e){ JFileChooser chooser = new JFileChooser(); ImageAccessory ia = new ImageAccessory(); chooser.setAccessory(ia); chooser.addPropertyChangeListener(ia); int option = chooser.showOpenDialog(parent); if(option == JFileChooser.APPROVE_OPTION){ statusbar.setText("You chose " + ((chooser.getSelectedFile() != null) ? chooser .getSelectedFile().getName() : "nothing")); } else { statusbar.setText("You canceled."); } } }); c.add(open); c.add(statusbar); setSize(200,300); } public static void main(String[] args){ new ImageFileChooser().setVisible(true); }}关键在于 需要设置JFileChooser的 accessory属性，我们在这个JPanel中来实现我们的东西。还要注意的是我们的JPanel类需要实现一个PropertyChangeListener类，这样，当你选择改变的时候，就可以在函数
propertyChange(PropertyChangeEvent ev)中实现动作了。
其中注意getScaledInstance(200, 300, Image.SCALE_DEFAULT);这个函数主要用来设置图片的大小。最后一个参数：Image.SCALE_DEFAULT是改变图像大小的算法。
要点就这么多。呵呵。试试看。
