将指定目录下的所有文件显示到列表框（JList）中。
代码如下：
1 import java.awt*;
2 import javax.swing*;
3 import java.util.*;
4 import java.io.*;
5
6 public class FileUtils extends JFrame
7 implements ChangeListener, ActionListener
8 {
9 private static final String VERSION = "Version 1.0";
10 private static final String WENJ_DIR = "文件";
11
12 private JList fileList;
13 private SoundEngine player;
14
15
16 public static void main(String[] args)
17 {
18 FileUtils gui = new FileUtils();
19 }
20
21
22 public FileUtils()
23 {
24 super("文件");
25 player = new SoundEngine();
26 String[] FileNames = findFiles(WENJ_DIR, null);
27 makeFrame(FileNames);
28 }
29
30
31
32 private void quit()
33 {
34 System.exit(0);
35 }
36
37
38
39 private void showAbout()
40 {
41 JOptionPane.showMessageDialog(this,
42 "文件
" + VERSION,
43 "About 文件",
44 JOptionPane.INFORMATION_MESSAGE);
45 }
46
47 private String[] findFiles(String dirName, String suffix)
48 {
49 File dir = new File(dirName);
50 if(dir.isDirectory()) {
51 String[] allFiles = dir.list();
52 if(suffix == null) {
53 return allFiles;
54 }
55 else {
56 List<String> selected = new ArrayList<String>();
57 for(String filename : allFiles) {
58 if(filename.endsWith(suffix)) {
59 selected.add(filename);
60 }
61 }
62 return selected.toArray(new String[selected.size()]);
63 }
64 }
65 else {
66 System.out.println("Error: " + dirName + " must be a directory");
67 return null;
68 }
69 }
70
71
72 public void stateChanged(ChangeEvent evt)
73 {
74
75 }
76
77 //添加监听器
78 public void actionPerformed(ActionEvent evt)
79 {
80 JComboBox cb = (JComboBox)evt.getSource();
81 String format = (String)cb.getSelectedItem();
82 if(format.equals("all")) {
83 format = null;
84 }
85 fileList.setListData(findFiles(WENJ_DIR, format));
86 }
87
88
89 private void makeFrame(String[] Files)
90 {
91
92 setDefaultCloseOperation(EXIT_ON_CLOSE);
93
94 JPanel contentPane = (JPanel)getContentPane();
95 contentPane.setBorder(new EmptyBorder(6, 10, 10, 10));
96
97 makeMenuBar();
98
99
100 contentPane.setLayout(new BorderLayout(8, 8));
101
102
103 JPanel leftPane = new JPanel();
104 {
105 leftPane.setLayout(new BorderLayout(8, 8));
106
107 String[] formats = { "all", ".doc", ".png", ".mp3" };
108
109
110 JComboBox formatList = new JComboBox(formats);
111 formatList.addActionListener(this);
112 leftPane.add(formatList, BorderLayout.NORTH);
113
114
115 fileList = new JList(Files);
116 fileList.setForeground(new Color(140,171,226));
117 fileList.setBackground(new Color(0,0,0));
118 fileList.setSelectionBackground(new Color(87,49,134));
119 fileList.setSelectionForeground(new Color(140,171,226));
120 JScrollPane scrollPane = new JScrollPane(fileList);
121 scrollPane.setColumnHeaderView(new JLabel("wenj files"));
122 leftPane.add(scrollPane, BorderLayout.CENTER);
123 }
124 contentPane.add(leftPane, BorderLayout.CENTER);
125
126 pack();
127
128 Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
129 setLocation(d.width/2 - getWidth()/2, d.height/2 - getHeight()/2);
130 setVisible(true);
131 }
132 //设置菜单项
133 private void makeMenuBar()
134 {
135 final int SHORTCUT_MASK =
136 Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
137
138 JMenuBar menubar = new JMenuBar();
139 setJMenuBar(menubar);
140
141 JMenu menu;
142 JMenuItem item;
143
144
145 menu = new JMenu("File");
146 menubar.add(menu);
147
148 item = new JMenuItem("Quit");
149 item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
150 item.addActionListener(new ActionListener() {
151 public void actionPerformed(ActionEvent e) { quit(); }
152 });
153 menu.add(item);
154
155
156 menu = new JMenu("Help");
157 menubar.add(menu);
158
159 item = new JMenuItem("About ...");
160 item.addActionListener(new ActionListener() {
161 public void actionPerformed(ActionEvent e) { showAbout(); }
162 });
163 menu.add(item);
164 }
165 }
