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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