第一个Java程序，简单的打开图片并显示在面板上

代码如下：

 1 import java.awt.Component;

 2 import java.awt.EventQueue;

 3 import java.awt.Graphics;

 4 import java.awt.event.*;

 5 import java.io.*;

 6 import javax.swing.*;

 7 

 8 public class HelloWorld {

 9 

10     /**

11      * @param args

12      */

13     public static void main(String[] args) {

14         // TODO Auto-generated method stub

15         EventQueue.invokeLater(new Runnable() {

16             

17             @Override

18             public void run() {

19                 // TODO Auto-generated method stub

20                 JFrame frame = new ImageViewerFrame();

21                 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

22                 frame.setVisible(true);

23             }

24         });

25     }

26 }

27 

28 class ImageViewerFrame extends JFrame{

29     public ImageViewerFrame(){

30         setTitle("ImageViewer");

31         setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

32         label = new JLabel();

33         add(label);

34         chooser = new JFileChooser();

35         chooser.setCurrentDirectory(new File("."));

36         JMenuBar menubar = new JMenuBar();

37         setJMenuBar(menubar);

38         JMenu menu = new JMenu("File");

39         menubar.add(menu);

40         JMenuItem openItem = new JMenuItem("Open");

41         menu.add(openItem);

42         JMenuItem exitItem = new JMenuItem("Close");

43         menu.add(exitItem);

44         openItem.addActionListener(new ActionListener() {

45             

46             @Override

47             public void actionPerformed(ActionEvent arg0) {

48                 // TODO Auto-generated method stub

49                 int result = chooser.showOpenDialog(null);

50                 if(result == JFileChooser.APPROVE_OPTION){

51                     String name = chooser.getSelectedFile().getPath();

52                     label.setIcon(new ImageIcon(name));

53                 }

54             }

55         });

56         exitItem.addActionListener(new ActionListener() {

57             

58             @Override

59             public void actionPerformed(ActionEvent arg0) {

60                 // TODO Auto-generated method stub

61                 System.exit(0);

62             }

63         });

64     }

65     private JLabel label;

66     private JFileChooser chooser;

67     private static final int DEFAULT_WIDTH = 300;

68     private static final int DEFAULT_HEIGHT = 400;

69 }

 显示效果如下：