看到很多人问关于用JTree实现资源管理器的方法，在这里我提供一个例子共大家参考，这个例子虽然也是转自其他书，但是JTree的用法，我掌握的差不多了，如果哪位朋友，对此例子有问题，我愿意与他交流。我的email是：[email protected]这个例子涵盖了JTree的大部分属性，希望对大家能够有所帮助。需要一些图标文件，请大家自己复制好相同名字的gif图片放到目录下。
下面是源代码:
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
public class FileTree1
extends JFrame
{
public static final ImageIcon ICON_COMPUTER =
new ImageIcon("computer.gif");
public static final ImageIcon ICON_DISK =
new ImageIcon("disk.gif");
public static final ImageIcon ICON_FOLDER =
new ImageIcon("folder.gif");
public static final ImageIcon ICON_EXPANDEDFOLDER =
new ImageIcon("expandedfolder.gif");
protected JTree m_tree;
protected DefaultTreeModel m_model;
protected JTextField m_display;
public FileTree1()
{
super("Directories Tree");
setSize(400, 300);
DefaultMutableTreeNode top = new DefaultMutableTreeNode(
new IconData(ICON_COMPUTER, null, "Computer"));
DefaultMutableTreeNode node;
File[] roots = File.listRoots();
for (int k=0; k<roots.length; k++)
{
node = new DefaultMutableTreeNode(new IconData(ICON_DISK,
null, new FileNode(roots[k])));
top.add(node);
node.add( new DefaultMutableTreeNode(new Boolean(true)));
}
m_model = new DefaultTreeModel(top);
m_tree = new JTree(m_model);
m_tree.putClientProperty("JTree.lineStyle", "Angled");
TreeCellRenderer renderer = new
IconCellRenderer();
m_tree.setCellRenderer(renderer);
m_tree.addTreeExpansionListener(new
DirExpansionListener());
m_tree.addTreeSelectionListener(new
DirSelectionListener());
m_tree.getSelectionModel().setSelectionMode(
TreeSelectionModel.SINGLE_TREE_SELECTION);
m_tree.setShowsRootHandles(true);
m_tree.setEditable(false);
JScrollPane s = new JScrollPane();
s.getViewport().add(m_tree);
getContentPane().add(s, BorderLayout.CENTER);
m_display = new JTextField();
m_display.setEditable(false);
getContentPane().add(m_display, BorderLayout.NORTH);
WindowListener wndCloser = new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
};
addWindowListener(wndCloser);
setVisible(true);
}
DefaultMutableTreeNode getTreeNode(TreePath path)
{
return (DefaultMutableTreeNode)(path.getLastPathComponent());
}
FileNode getFileNode(DefaultMutableTreeNode node)
{
if (node == null)
return null;
Object obj = node.getUserObject();
if (obj instanceof IconData)
obj = ((IconData)obj).getObject();
if (obj instanceof FileNode)
return (FileNode)obj;
else
return null;
}
// Make sure expansion is threaded and updating the tree model
// only occurs within the event dispatching thread.
class DirExpansionListener implements TreeExpansionListener
{
public void treeExpanded(TreeExpansionEvent event)
{
final DefaultMutableTreeNode node = getTreeNode(
event.getPath());
final FileNode fnode = getFileNode(node);
Thread runner = new Thread()
{
public void run()
{
if (fnode != null && fnode.expand(node))
{
Runnable runnable = new Runnable()
{
public void run()
{
m_model.reload(node);
}
};
SwingUtilities.invokeLater(runnable);
}
}
};
runner.start();
}
public void treeCollapsed(TreeExpansionEvent event) {}
}
class DirSelectionListener
implements TreeSelectionListener
{
public void valueChanged(TreeSelectionEvent event)
{
DefaultMutableTreeNode node = getTreeNode(
event.getPath());
FileNode fnode = getFileNode(node);
if (fnode != null)
m_display.setText(fnode.getFile().
getAbsolutePath());
else
m_display.setText("");
}
}
public static void main(String argv[])
{
new FileTree1();
}
}
class IconCellRenderer
extends JLabel
implements TreeCellRenderer
{
protected Color m_textSelectionColor;
protected Color m_textNonSelectionColor;
protected Color m_bkSelectionColor;
protected Color m_bkNonSelectionColor;
protected Color m_borderSelectionColor;
protected boolean m_selected;
public IconCellRenderer()
{
super();
m_textSelectionColor = UIManager.getColor(
"Tree.selectionForeground");
m_textNonSelectionColor = UIManager.getColor(
"Tree.textForeground");
m_bkSelectionColor = UIManager.getColor(
"Tree.selectionBackground");
m_bkNonSelectionColor = UIManager.getColor(
"Tree.textBackground");
m_borderSelectionColor = UIManager.getColor(
"Tree.selectionBorderColor");
setOpaque(false);
}
public Component getTreeCellRendererComponent(JTree tree,
Object value, boolean sel, boolean expanded, boolean leaf,
int row, boolean hasFocus)
{
DefaultMutableTreeNode node =
(DefaultMutableTreeNode)value;
Object obj = node.getUserObject();
setText(obj.toString());
if (obj instanceof Boolean)
setText("Retrieving data...");
if (obj instanceof IconData)
{
IconData idata = (IconData)obj;
if (expanded)
setIcon(idata.getExpandedIcon());
else
setIcon(idata.getIcon());
}
else
setIcon(null);
setFont(tree.getFont());
setForeground(sel ? m_textSelectionColor :
m_textNonSelectionColor);
setBackground(sel ? m_bkSelectionColor :
m_bkNonSelectionColor);
m_selected = sel;
return this;
}
public void paintComponent(Graphics g)
{
Color bColor = getBackground();
Icon icon = getIcon();
g.setColor(bColor);
int offset = 0;
if(icon != null && getText() != null)
offset = (icon.getIconWidth() + getIconTextGap());
g.fillRect(offset, 0, getWidth() - 1 - offset,
getHeight() - 1);
if (m_selected)
{
g.setColor(m_borderSelectionColor);
g.drawRect(offset, 0, getWidth()-1-offset, getHeight()-1);
}
super.paintComponent(g);
}
}
class IconData
{
protected Icon m_icon;
protected Icon m_expandedIcon;
protected Object m_data;
public IconData(Icon icon, Object data)
{
m_icon = icon;
m_expandedIcon = null;
m_data = data;
}
public IconData(Icon icon, Icon expandedIcon, Object data)
{
m_icon = icon;
m_expandedIcon = expandedIcon;
m_data = data;
}
public Icon getIcon()
{
return m_icon;
}
public Icon getExpandedIcon()
{
return m_expandedIcon!=null ? m_expandedIcon : m_icon;
}
public Object getObject()
{
return m_data;
}
public String toString()
{
return m_data.toString();
}
}
class FileNode
{
protected File m_file;
public FileNode(File file)
{
m_file = file;
}
public File getFile()
{
return m_file;
}
public String toString()
{
return m_file.getName().length() > 0 ? m_file.getName() :
m_file.getPath();
}
public boolean expand(DefaultMutableTreeNode parent)
{
DefaultMutableTreeNode flag =
(DefaultMutableTreeNode)parent.getFirstChild();
if (flag==null) // No flag
return false;
Object obj = flag.getUserObject();
if (!(obj instanceof Boolean))
return false; // Already expanded
parent.removeAllChildren(); // Remove Flag
File[] files = listFiles();
if (files == null)
return true;
Vector v = new Vector();
for (int k=0; k<files.length; k++)
{
File f = files[k];
if (!(f.isDirectory()))
continue;
FileNode newNode = new FileNode(f);
boolean isAdded = false;
for (int i=0; i<v.size(); i++)
{
FileNode nd = (FileNode)v.elementAt(i);
if (newNode.compareTo(nd) < 0)
{
v.insertElementAt(newNode, i);
isAdded = true;
break;
}
}
if (!isAdded)
v.addElement(newNode);
}
for (int i=0; i<v.size(); i++)
{
FileNode nd = (FileNode)v.elementAt(i);
IconData idata = new IconData(FileTree1.ICON_FOLDER,
FileTree1.ICON_EXPANDEDFOLDER, nd);
DefaultMutableTreeNode node = new
DefaultMutableTreeNode(idata);
parent.add(node);
if (nd.hasSubDirs())
node.add(new DefaultMutableTreeNode(
new Boolean(true) ));
}
return true;
}
public boolean hasSubDirs()
{
File[] files = listFiles();
if (files == null)
return false;
for (int k=0; k<files.length; k++)
{
if (files[k].isDirectory())
return true;
}
return false;
}
public int compareTo(FileNode toCompare)
{
return m_file.getName().compareToIgnoreCase(
toCompare.m_file.getName() );
}
protected File[] listFiles()
{
if (!m_file.isDirectory())
return null;
try
{
return m_file.listFiles();
}
catch (Exception ex)
{
JOptionPane.showMessageDialog(null,
"Error reading directory "+m_file.getAbsolutePath(),
"Warning", JOptionPane.WARNING_MESSAGE);
return null;
}
}
}
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