JTree事件

package com.wf;

import javax.swing.*;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreePath;
import java.awt.*;

class  PaintUserData
{
    public static Color _color = Color.BLACK;

}

class ProjectTree extends JTree implements TreeSelectionListener
{

    private JPanel _panel;

    public ProjectTree(JPanel panel) {
        addTreeSelectionListener(this);
        _panel = panel;
    }

    @Override
    public void valueChanged(TreeSelectionEvent e) {
        TreePath path = e.getNewLeadSelectionPath();
        DefaultMutableTreeNode node = (DefaultMutableTreeNode)path.getLastPathComponent();

        if (node.getUserObject().equals("red"))
        {
            PaintUserData._color = Color.red;

        }
        else if (node.getUserObject().equals("blue"))
        {
            PaintUserData._color = Color.blue;

        }
        else if (node.getUserObject().equals("yellow"))
        {
            PaintUserData._color = Color.yellow;
        }
        else if (node.getUserObject().equals("violet"))
        {
            PaintUserData._color = Color.CYAN;
        }
        else
        {
            PaintUserData._color = Color.black;

        }
        _panel.repaint();
    }

}

class PaintPanel extends JPanel
{

    public PaintPanel() {

    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);

        g.setColor(PaintUserData._color);
        g.drawLine(0, 0, 400, 400);

    }

}

class MainWidget extends JComponent
{
    private GridBagConstraints _gbScrollPane;
    private GridBagConstraints _gbPaintPanel;
    private GridBagLayout _layout;

    private JScrollPane _scrollPane;
    private ProjectTree _projectTree;
    private PaintPanel _paintPanel;
    public MainWidget() {
        _gbScrollPane = new GridBagConstraints();
        _gbPaintPanel = new GridBagConstraints();

        _gbScrollPane.weightx = 0.1;
        _gbScrollPane.weighty = 1;
        _gbScrollPane.gridx = 0;
        _gbScrollPane.gridy = 0;
        _gbScrollPane.fill = GridBagConstraints.BOTH;

        _gbPaintPanel.weightx = 0.9;
        _gbPaintPanel.weighty = 0;
        _gbPaintPanel.gridx = 1;
        _gbPaintPanel.gridy = 0;
        _gbPaintPanel.fill = GridBagConstraints.BOTH;

        _layout = new GridBagLayout();
        setLayout(_layout);

        _scrollPane = new JScrollPane();

        _paintPanel = new PaintPanel();
        _projectTree = new ProjectTree(_paintPanel);

        _scrollPane.getViewport().add(_projectTree);
        add(_scrollPane, _gbScrollPane);

        add(_paintPanel, _gbPaintPanel);

    }

}
public class Test01 extends JFrame
{
    private MainWidget _mainWidget;

    public Test01() {
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        _mainWidget = new MainWidget();

        getContentPane().add(_mainWidget);
    }

    public static void main(String[] args) throws Exception{
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {

                Test01 f = new Test01();
                f.setSize(1024, 800);
                f.setLocationRelativeTo(null);
                f.setVisible(true);
            }
        });
    }
}