做東西的時候需要實現資源管理器樹形目錄。正好在網上搜到這么個源代碼，當邊用邊學習了 :)
1
import java.awt.*;
2import java.awt.event.*;
3import java.io.*;
4import java.util.*;
5
6import javax.swing.*;
7import javax.swing.tree.*;
8import javax.swing.event.*;
9
10public class FileTree1
11 extends JFrame
12
{
13
public static final ImageIcon ICON_COMPUTER =
14 new ImageIcon("computer.gif");
15 public static final ImageIcon ICON_DISK =
16 new ImageIcon("disk.gif");
17 public static final ImageIcon ICON_FOLDER =
18 new ImageIcon("folder.gif");
19 public static final ImageIcon ICON_EXPANDEDFOLDER =
20 new ImageIcon("expandedfolder.gif");
21
22 protected JTree m_tree;
23 protected DefaultTreeModel m_model;
24 protected JTextField m_display;
25
26 public FileTree1()
27
{
28 super("Directories Tree");
29 setSize(400, 300);
30
31 DefaultMutableTreeNode top = new DefaultMutableTreeNode(
32 new IconData(ICON_COMPUTER, null, "Computer"));
33
34 DefaultMutableTreeNode node;
35 File[] roots = File.listRoots();
36 for (int k=0; k<roots.length; k++)
37 {
38 node = new DefaultMutableTreeNode(new IconData(ICON_DISK,
39 null, new FileNode(roots[k])));
40 top.add(node);
41 node.add( new DefaultMutableTreeNode(new Boolean(true)));
42
}
43
44 m_model = new DefaultTreeModel(top);
45 m_tree = new JTree(m_model);
46 m_tree.putClientProperty("JTree.lineStyle", "Angled");
47
48 TreeCellRenderer renderer = new
49 IconCellRenderer();
50 m_tree.setCellRenderer(renderer);
51
52 m_tree.addTreeExpansionListener(new
53 DirExpansionListener());
54
55 m_tree.addTreeSelectionListener(new
56 DirSelectionListener());
57
58 m_tree.getSelectionModel().setSelectionMode(
59 TreeSelectionModel.SINGLE_TREE_SELECTION);
60 m_tree.setShowsRootHandles(true);
61 m_tree.setEditable(false);
62
63 JScrollPane s = new JScrollPane();
64 s.getViewport().add(m_tree);
65 getContentPane().add(s, BorderLayout.CENTER);
66
67 m_display = new JTextField();
68 m_display.setEditable(false);
69 getContentPane().add(m_display, BorderLayout.NORTH);
70
71 WindowListener wndCloser = new WindowAdapter()
72 {
73 public void windowClosing(WindowEvent e)
74 {
75 System.exit(0);
76 }
77 };
78 addWindowListener(wndCloser);
79
80 setVisible(true);
81 }
82
83 DefaultMutableTreeNode getTreeNode(TreePath path)
84 {
85 return (DefaultMutableTreeNode)(path.getLastPathComponent());
86 }
87
88 FileNode getFileNode(DefaultMutableTreeNode node)
89 {
90 if (node == null)
91 return null;
92 Object obj = node.getUserObject();
93 if (obj instanceof IconData)
94 obj = ((IconData)obj).getObject();
95 if (obj instanceof FileNode)
96 return (FileNode)obj;
97 else
98 return null;
99 }
100
101 // Make sure expansion is threaded and updating the tree model
102 // only occurs within the event dispatching thread.
103 class DirExpansionListener implements TreeExpansionListener
104 {
105 public void treeExpanded(TreeExpansionEvent event)
106 {
107 final DefaultMutableTreeNode node = getTreeNode(
108 event.getPath());
109 final FileNode fnode = getFileNode(node);
110
111 Thread runner = new Thread()
112 {
113 public void run()
114 {
115 if (fnode != null && fnode.expand(node))
116 {
117 Runnable runnable = new Runnable()
118 {
119 public void run()
120 {
121 m_model.reload(node);
122 }
123 };
124 SwingUtilities.invokeLater(runnable);
125 }
126 }
127 };
128 runner.start();
129 }
130
131 public void treeCollapsed(TreeExpansionEvent event) {}
132 }
133
134
135 class DirSelectionListener
136 implements TreeSelectionListener
137 {
138 public void valueChanged(TreeSelectionEvent event)
139 {
140 DefaultMutableTreeNode node = getTreeNode(
141 event.getPath());
142 FileNode fnode = getFileNode(node);
143 if (fnode != null)
144 m_display.setText(fnode.getFile().
145 getAbsolutePath());
146 else
147 m_display.setText("");
148 }
149 }
150
151 public static void main(String argv[])
152 {
153 new FileTree1();
154 }
155
}
156
157class IconCellRenderer
158 extends JLabel
159 implements TreeCellRenderer
160{
161 protected Color m_textSelectionColor;
162 protected Color m_textNonSelectionColor;
163 protected Color m_bkSelectionColor;
164 protected Color m_bkNonSelectionColor;
165 protected Color m_borderSelectionColor;
166
167 protected boolean m_selected;
168
169 public IconCellRenderer()
170 {
171 super();
172 m_textSelectionColor = UIManager.getColor(
173 "Tree.selectionForeground");
174 m_textNonSelectionColor = UIManager.getColor(
175 "Tree.textForeground");
176 m_bkSelectionColor = UIManager.getColor(
177 "Tree.selectionBackground");
178 m_bkNonSelectionColor = UIManager.getColor(
179 "Tree.textBackground");
180 m_borderSelectionColor = UIManager.getColor(
181 "Tree.selectionBorderColor");
182 setOpaque(false);
183 }
184
185 public Component getTreeCellRendererComponent(JTree tree,
186 Object value, boolean sel, boolean expanded, boolean leaf,
187 int row, boolean hasFocus)
188
189 {
190 DefaultMutableTreeNode node =
191 (DefaultMutableTreeNode)value;
192 Object obj = node.getUserObject();
193 setText(obj.toString());
194
195 if (obj instanceof Boolean)
196 setText("Retrieving data");
197
198 if (obj instanceof IconData)
199 {
200 IconData idata = (IconData)obj;
201 if (expanded)
202 setIcon(idata.getExpandedIcon());
203 else
204 setIcon(idata.getIcon());
205 }
206 else
207 setIcon(null);
208
209 setFont(tree.getFont());
210 setForeground(sel ? m_textSelectionColor :
211 m_textNonSelectionColor);
212 setBackground(sel ? m_bkSelectionColor :
213 m_bkNonSelectionColor);
214 m_selected = sel;
215 return this;
216 }
217
218
219 public void paintComponent(Graphics g)
220 {
221 Color bColor = getBackground();
222 Icon icon = getIcon();
223
224 g.setColor(bColor);
225 int offset = 0;
226 if(icon != null && getText() != null)
227 offset = (icon.getIconWidth() + getIconTextGap());
228 g.fillRect(offset, 0, getWidth() - 1 - offset,
229 getHeight() - 1);
230
231 if (m_selected)
232 {
233 g.setColor(m_borderSelectionColor);
234 g.drawRect(offset, 0, getWidth()-1-offset, getHeight()-1);
235 }
236 super.paintComponent(g);
237 }
238}
239
240class IconData
241{
242 protected Icon m_icon;
243 protected Icon m_expandedIcon;
244 protected Object m_data;
245
246 public IconData(Icon icon, Object data)
247 {
248 m_icon = icon;
249 m_expandedIcon = null;
250 m_data = data;
251 }
252
253 public IconData(Icon icon, Icon expandedIcon, Object data)
254 {
255 m_icon = icon;
256 m_expandedIcon = expandedIcon;
257 m_data = data;
258 }
259
260 public Icon getIcon()
261 {
262 return m_icon;
263 }
264
265 public Icon getExpandedIcon()
266 {
267 return m_expandedIcon!=null ? m_expandedIcon : m_icon;
268 }
269
270 public Object getObject()
271 {
272 return m_data;
273 }
274
275 public String toString()
276 {
277 return m_data.toString();
278 }
279}
280
281class FileNode
282{
283 protected File m_file;
284
285 public FileNode(File file)
286 {
287 m_file = file;
288 }
289
290 public File getFile()
291 {
292 return m_file;
293 }
294
295 public String toString()
296 {
297 return m_file.getName().length() > 0 ? m_file.getName() :
298 m_file.getPath();
299 }
300
301 public boolean expand(DefaultMutableTreeNode parent)
302 {
303 DefaultMutableTreeNode flag =
304 (DefaultMutableTreeNode)parent.getFirstChild();
305 if (flag==null) // No flag
306 return false;
307 Object obj = flag.getUserObject();
308 if (!(obj instanceof Boolean))
309 return false; // Already expanded
310
311 parent.removeAllChildren(); // Remove Flag
312
313 File[] files = listFiles();
314 if (files == null)
315 return true;
316
317 Vector v = new Vector();
318
319 for (int k=0; k<files.length; k++)
320 {
321 File f = files[k];
322 if (!(f.isDirectory()))
323 continue;
324
325 FileNode newNode = new FileNode(f);
326
327 boolean isAdded = false;
328 for (int i=0; i<v.size(); i++)
329 {
330 FileNode nd = (FileNode)v.elementAt(i);
331 if (newNode.compareTo(nd) < 0)
332 {
333 v.insertElementAt(newNode, i);
334 isAdded = true;
335 break;
336 }
337 }
338 if (!isAdded)
339 v.addElement(newNode);
340 }
341
342 for (int i=0; i<v.size(); i++)
343 {
344 FileNode nd = (FileNode)v.elementAt(i);
345 IconData idata = new IconData(FileTree1.ICON_FOLDER,
346 FileTree1.ICON_EXPANDEDFOLDER, nd);
347 DefaultMutableTreeNode node = new
348 DefaultMutableTreeNode(idata);
349 parent.add(node);
350
351 if (nd.hasSubDirs())
352 node.add(new DefaultMutableTreeNode(
353 new Boolean(true) ));
354 }
355
356 return true;
357 }
358
359 public boolean hasSubDirs()
360 {
361 File[] files = listFiles();
362 if (files == null)
363 return false;
364 for (int k=0; k<files.length; k++)
365 {
366 if (files[k].isDirectory())
367 return true;
368 }
369 return false;
370 }
371
372 public int compareTo(FileNode toCompare)
373 {
374 return m_file.getName().compareToIgnoreCase(
375 toCompare.m_file.getName() );
376 }
377
378 protected File[] listFiles()
379 {
380 if (!m_file.isDirectory())
381 return null;
382 try
383 {
384 return m_file.listFiles();
385 }
386 catch (Exception ex)
387 {
388 JOptionPane.showMessageDialog(null,
389 "Error reading directory "+m_file.getAbsolutePath(),
390 "Warning", JOptionPane.WARNING_MESSAGE);
391 return null;
392 }
393 }
394}
395
396