JTreeComboBox--Swing树形下拉框

    最近公司用SWing开发时，需要实现网友们称为的“树形下拉框的”效果。关于此效果B/S模式很容易实现，放到Swing上面事先就有点困难。这个东西弄了将近一下午，终于出效果了。先分享出去。希望共同提高！

package com.pos.utils.tree;

import java.awt.*;

/**
 * @author wanghaoqian
 * Description: 树形下拉列表框
 */
public class JTreeComboBox extends JComboBox {
	/**
	 * 显示用的树
	 */
	private JTree tree;

	public JTreeComboBox() {
		this(new JTree());
	}

	public JTreeComboBox(JTree tree) {
		this.setTree(tree);
	}

	/**
	 * 设置树
	 * 
	 * @param tree
	 *            JTree
	 */
	public void setTree(JTree tree) {
		this.tree = tree;
		if (tree != null) {
			this.setSelectedItem(tree.getSelectionPath());
			this.setRenderer(new JTreeComboBoxRenderer());
		}
		this.updateUI();
	}

	/**
	 * 取得树
	 * 
	 * @return JTree
	 */
	public JTree getTree() {
		return tree;
	}

	/**
	 * 设置当前选择的树路径
	 * 
	 * @param o
	 *            Object
	 */
	public void setSelectedItem(Object o) {
		tree.setSelectionPath((TreePath) o);
		getModel().setSelectedItem(o);
	}

	public void updateUI() {
		ComboBoxUI cui = (ComboBoxUI) UIManager.getUI(this);
		if (cui instanceof MetalComboBoxUI) {
			cui = new MetalJTreeComboBoxUI();
		} else if (cui instanceof MotifComboBoxUI) {
			cui = new MotifJTreeComboBoxUI();
		} else {
			cui = new WindowsJTreeComboBoxUI();
		}
		setUI(cui);
	}

	// UI Inner classes -- one for each supported Look and Feel
	class MetalJTreeComboBoxUI extends MetalComboBoxUI {
		protected ComboPopup createPopup() {
			return new TreePopup(comboBox);
		}
	}

	class WindowsJTreeComboBoxUI extends WindowsComboBoxUI {
		protected ComboPopup createPopup() {
			return new TreePopup(comboBox);
		}
	}

	class MotifJTreeComboBoxUI extends MotifComboBoxUI {
		protected ComboPopup createPopup() {
			return new TreePopup(comboBox);
		}
	}

	/**
	 * 
	 * Description: 树形结构而来的DefaultListCellRenderer
	 */
	class JTreeComboBoxRenderer extends DefaultListCellRenderer {
		public Component getListCellRendererComponent(JList list, Object value,
				int index, boolean isSelected, boolean cellHasFocus) {
			if (value != null) {
				TreePath path = (TreePath) value;
				TreeNode node = (TreeNode) path.getLastPathComponent();
				value = node;
				TreeCellRenderer r = tree.getCellRenderer();
				JLabel lb = (JLabel) r.getTreeCellRendererComponent(tree,
						value, isSelected, false, node.isLeaf(), index,
						cellHasFocus);
				return lb;
			}
			return super.getListCellRendererComponent(list, value, index,
					isSelected, cellHasFocus);
		}
	}

	/**
	 * 测试
	 */
	public static void main(String args[]) {
		JFrame frame = new JFrame("JTreeComboBox 例子");
		frame.setSize(400, 320);
		Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
		frame.setLocation((d.width - frame.getSize().width) / 2,
				(d.height - frame.getSize().height) / 2);
		frame.getContentPane().setLayout(new FlowLayout());
		final JTreeComboBox box = new JTreeComboBox(new JTree());
		box.setPreferredSize(new Dimension(300, 21));
		frame.getContentPane().add(box);
		final JButton btt = new JButton("保存");
		btt.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				box.setTree(new JTree());
				btt.setEnabled(false);
			}
		});
		frame.getContentPane().add(btt);
		frame.setVisible(true);
	}
}

/**
 * <p>
 * Description: TreePopup
 * </p>
 */
class TreePopup extends JPopupMenu implements ComboPopup {
	protected JTreeComboBox comboBox;
	protected JScrollPane scrollPane;

	protected MouseMotionListener mouseMotionListener;
	protected MouseListener mouseListener;
	private MouseListener treeSelectListener = new MouseAdapter() {
		public void mouseReleased(MouseEvent e) {
			JTree tree = (JTree) e.getSource();
			TreePath tp = tree.getPathForLocation(e.getPoint().x,
					e.getPoint().y);
			if (tp == null) {
				return;
			}
			comboBox.setSelectedItem(tp);
			togglePopup();
			MenuSelectionManager.defaultManager().clearSelectedPath();
		}
	};

	public TreePopup(JComboBox comboBox) {
		this.comboBox = (JTreeComboBox) comboBox;
		setBorder(BorderFactory.createLineBorder(Color.black));
		setLayout(new BorderLayout());
		setLightWeightPopupEnabled(comboBox.isLightWeightPopupEnabled());
		JTree tree = this.comboBox.getTree();
		if (tree != null) {
			scrollPane = new JScrollPane(tree);
			scrollPane.setBorder(null);
			add(scrollPane, BorderLayout.CENTER);
			tree.addMouseListener(treeSelectListener);
		}
	}

	public void show() {
		updatePopup();
		show(comboBox, 0, comboBox.getHeight());
		comboBox.getTree().requestFocus();
	}

	public void hide() {
		setVisible(false);
		comboBox.firePropertyChange("popupVisible", true, false);
	}

	protected JList list = new JList();

	public JList getList() {
		return list;
	}

	public MouseMotionListener getMouseMotionListener() {
		if (mouseMotionListener == null) {
			mouseMotionListener = new MouseMotionAdapter() {
			};
		}
		return mouseMotionListener;
	}

	public KeyListener getKeyListener() {
		return null;
	}

	public void uninstallingUI() {
	}

	/**
	 * Implementation of ComboPopup.getMouseListener().
	 * 
	 * @return a <code>MouseListener</code> or null
	 * @see ComboPopup#getMouseListener
	 */
	public MouseListener getMouseListener() {
		if (mouseListener == null) {
			mouseListener = new InvocationMouseHandler();
		}
		return mouseListener;
	}

	protected void togglePopup() {
		if (isVisible()) {
			hide();
		} else {
			show();
		}
	}

	protected void updatePopup() {
		setPreferredSize(new Dimension(comboBox.getSize().width, 200));
		Object selectedObj = comboBox.getSelectedItem();
		if (selectedObj != null) {
			TreePath tp = (TreePath) selectedObj;
			((JTreeComboBox) comboBox).getTree().setSelectionPath(tp);
		}
	}

	protected class InvocationMouseHandler extends MouseAdapter {
		public void mousePressed(MouseEvent e) {
			if (!SwingUtilities.isLeftMouseButton(e) || !comboBox.isEnabled()) {
				return;
			}
			if (comboBox.isEditable()) {
				Component comp = comboBox.getEditor().getEditorComponent();
				if ((!(comp instanceof JComponent))
						|| ((JComponent) comp).isRequestFocusEnabled()) {
					comp.requestFocus();
				}
			} else if (comboBox.isRequestFocusEnabled()) {
				comboBox.requestFocus();
			}
			togglePopup();
		}
	}
}