关于JTree的问题

[LoveXiaoShuang]

请问各位大虾，我想把系统里面的本地磁盘列到JTree里面，就像有些软件选择目录（文件夹）的窗口一样，可以进行对本地磁盘的查询，提取在本地磁盘上面选择的目录文件夹，请问这个应该怎么实现呢？希望各位帮帮忙，最好附源码，谢谢！

[gtlang78]

import java.io.File;
import java.util.*;

import javax.swing.filechooser.FileSystemView;
import javax.swing.tree.TreeNode;

public class DirTreeNode implements TreeNode {
private File dir = null;

private List<DirTreeNode> children = null;

private DirTreeNode parent;

public DirTreeNode(File dir, DirTreeNode parent) {
this.dir = dir;
this.parent = parent;
}

public TreeNode getChildAt(int childIndex) {
initChildrenList();

return (TreeNode) children.get(childIndex);
}

public int getChildCount() {
initChildrenList();

return children.size();
}

public TreeNode getParent() {
return parent;
}

public int getIndex(TreeNode node) {
initChildrenList();

return children.indexOf(node);
}

public boolean getAllowsChildren() {
return true;
}

public boolean isLeaf() {
if (dir != null && FileSystemView.getFileSystemView().isFloppyDrive(dir)) {
return false;
}

initChildrenList();

return children.isEmpty();
}

public Enumeration children() {
initChildrenList();

final Iterator iter = children.iterator();
return new Enumeration() {
public boolean hasMoreElements() {
return iter.hasNext();
}

public Object nextElement() {
return iter.next();
}
};
}

private void initChildrenList() {
if (children == null) {
File[] subDirs = null;
if (dir == null) {
subDirs = FileSystemView.getFileSystemView().getRoots();
}
else {
subDirs = FileSystemView.getFileSystemView().getFiles(dir, false);
}
if (subDirs == null || subDirs.length == 0) {
children = Collections.emptyList();
}
else {
children = new ArrayList<DirTreeNode>();
for (int i = 0; i < subDirs.length; i++) {
if (subDirs[i]!= null && subDirs[i].isDirectory()) {
children.add(new DirTreeNode(subDirs[i], this));
}
}
}
}
}

public File getDir() {
return dir;
}

public String toString() {
return dir == null ?
"" : FileSystemView.getFileSystemView().getSystemDisplayName(dir);
}

public boolean equals(Object obj) {
if (obj instanceof DirTreeNode) {
DirTreeNode t = (DirTreeNode) obj;
return dir == null ? t.dir == null : dir.equals(t.dir);
}
return false;
}

public int hashCode() {
return dir == null ? 0 : dir.hashCode();
}

}

[gtlang78]

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import javax.swing.*;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.filechooser.FileSystemView;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreePath;

public class DirChooserDialog
extends JDialog
{
private JLabel descrLabel = new JLabel("", JLabel.LEFT);
private JTree dirTree = null;
private JScrollPane scrollPane = null;

private JButton okBtn = new JButton("确定");
private JButton cancleBtn = new JButton("取消");

private JPanel btnPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT));
private boolean okBtnPressed;

public DirChooserDialog(Frame owner, String dialogTitle, String descrStr) {
super(owner, dialogTitle, true);

initComponents(descrStr);
}

public DirChooserDialog(Dialog owner, String dialogTitle, String descrStr) {
super(owner, dialogTitle, true);

initComponents(descrStr);
}

private void initComponents(String descrStr)
{
descrLabel.setText(descrStr);

btnPanel.add(okBtn);
btnPanel.add(cancleBtn);

DirTreeNode rootNode = new DirTreeNode(null, null);
dirTree = new JTree(rootNode);
dirTree.setCellRenderer(new DefaultTreeCellRenderer() {
public Component getTreeCellRendererComponent(
JTree tree, Object value, boolean sel, boolean expanded,
boolean leaf, int row, boolean hasFocus) {

super.getTreeCellRendererComponent(
tree, value, sel, expanded, leaf, row, hasFocus);

DirTreeNode node = (DirTreeNode) value;
if (node.getDir() != null) {
setIcon(FileSystemView.getFileSystemView().getSystemIcon(node.getDir()));
}
return this;
}
});
dirTree.addTreeSelectionListener(new TreeSelectionListener() {
public void valueChanged(TreeSelectionEvent e)
{
updateOKBtnState();
}
});
dirTree.setRootVisible(false);
dirTree.expandRow(0);
JScrollPane scrollPane = new JScrollPane(dirTree);
scrollPane.setPreferredSize(new Dimension(300, 300));

okBtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
okBtnPressed = true;
dispose();
}
});

cancleBtn.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
okBtnPressed = false;
dispose();
}
});

((JComponent) getContentPane()).setBorder(BorderFactory.createEmptyBorder(10, 10, 5, 10));
getContentPane().setLayout(new BorderLayout(5, 5));

getContentPane().add(descrLabel, BorderLayout.NORTH);
getContentPane().add(scrollPane, BorderLayout.CENTER);
getContentPane().add(btnPanel, BorderLayout.SOUTH);

setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);

updateOKBtnState();
pack();
}

private void updateOKBtnState()
{
okBtn.setEnabled(getSelectedDir() != null);
}

public File showDirChooserDialog() {
okBtnPressed = false;

Rectangle bounds = getParent().getBounds();
setLocation(bounds.x + (bounds.width - getWidth()) / 2 ,
bounds.y + (bounds.height - getHeight()) / 2);
setVisible(true);

if (okBtnPressed) {
return getSelectedDir();
}
else {
return null;
}
}

public File getSelectedDir() {
TreePath path = dirTree.getSelectionPath();
if (path == null || path.getPathCount() == 1) {
return null;
}
DirTreeNode node = (DirTreeNode) path.getLastPathComponent();

return node.getDir();
}

public void setSelectedDir(File dir) {
List<File> pathList = new LinkedList<File>();
do {
pathList.add(0, dir);
dir = dir.getParentFile();
} while (dir != null);

TreePath path = new TreePath(dirTree.getModel().getRoot());
for (Iterator iter = pathList.iterator(); iter.hasNext();) {
File d = (File) iter.next();
path = path.pathByAddingChild(
new DirTreeNode(d, (DirTreeNode) path.getLastPathComponent()));
}

dirTree.setSelectionPath(path);
dirTree.scrollPathToVisible(path);
}

public static void main(String[] args)
{
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception e) {
e.printStackTrace();
}

final JFrame f = new JFrame("DirChooserTest");

JButton btn = new JButton("ChooseDir");
btn.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
DirChooserDialog dlg = new DirChooserDialog(f, "DirChooserDialog", "选择保存文件的目录:");
//dlg.setSelectedDir(new File("F:/temp"));
System.out.println(dlg.showDirChooserDialog());
}
});

f.getContentPane().add(btn, BorderLayout.CENTER);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}

[LoveXiaoShuang]

非常感谢，不过我有个地方没有搞明白，就是像
List<File> pathList = new LinkedList<File>();这样的语句，为什么用<>这个符号？我告白明白，编译器也报错，不知道是什么问题？

[gtlang78]

这是1.5里面新加的语法，如果你用1.4的话就把所有的<>都删掉，然后有些地方需要加上强制类型转换

[LoveXiaoShuang]

怎么，真的没有人会？

[LoveXiaoShuang]

谢谢你，我使用的1.5的JVM通过了编译，但是你能不能讲一下，<>的作用，什么时候用，是做什么用的可以吗？

[gtlang78]

http://java.sun.com/j2se/1.5/pdf/generics-tutorial.pdf