java swing 仿xp左侧菜单（AccordionPanel）

// -*- mode:java; encoding:utf-8 -*-
// vim:set fileencoding=utf-8:
// @homepage@

package example;

import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Stream;
import javax.swing.*;
import javax.swing.border.Border;

public final class MainPanel extends JPanel {
  // private final Box box = Box.createVerticalBox（）;
  // private final Component glue = Box.createVerticalGlue（）;
  private MainPanel（） {
    super（new BorderLayout（））;

    Box accordion = Box.createVerticalBox（）;
    accordion.setOpaque（true）;
    accordion.setBackground（new Color（0xB4_B4_FF））;
    accordion.setBorder（BorderFactory.createEmptyBorder（10 5 5 5））;
    makeExpansionPanelList（）.forEach（p -> {
      accord

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     文件       22539  2019-08-23 17:36  build.xml
     目录           0  2019-08-24 08:49  config\
     文件         423  2019-08-23 17:36  config\jnlp.xml
     文件        2145  2019-08-23 17:36  config\properties.xml
     文件         152  2019-08-23 17:36  config.gradle
     文件         526  2019-08-23 17:36  run.bat
     文件         614  2019-08-23 17:36  run.sh
     目录           0  2019-08-24 08:49  src\
     目录           0  2019-08-24 08:49  src\java\
     目录           0  2019-08-24 08:49  src\java\example\
     文件        6686  2019-08-23 17:36  src\java\example\MainPanel.java
     目录           0  2019-08-24 08:49  src\web\
     文件         537  2019-08-23 17:36  src\web\example.jnlp
     文件         341  2019-08-23 17:36  src\web\index.html
     文件       10450  2019-08-23 17:36  src\web\screenshot.png
     目录           0  2019-08-24 11:03  target\
     目录           0  2019-08-24 11:03  target\classes\
     目录           0  2019-08-24 11:03  target\classes\example\
     文件        1294  2019-08-24 11:03  target\classes\example\AbstractExpansionPanel$1.class
     文件         730  2019-08-24 11:03  target\classes\example\AbstractExpansionPanel$2.class
     文件        3828  2019-08-24 11:03  target\classes\example\AbstractExpansionPanel.class
     文件        2183  2019-08-24 11:03  target\classes\example\MainPanel$1.class
     文件        2106  2019-08-24 11:03  target\classes\example\MainPanel$2.class
     文件        2572  2019-08-24 11:03  target\classes\example\MainPanel$3.class
     文件         516  2019-08-24 11:03  target\classes\example\MainPanel$4.class
     文件        4495  2019-08-24 11:03  target\classes\example\MainPanel.class
     文件         645  2019-08-24 11:03  target\example.jnlp
     文件         515  2019-08-24 11:03  target\index.html
     文件       10450  2019-08-24 11:03  target\screenshot.png
     目录           0  2019-08-24 11:03  target\src\
     目录           0  2019-08-24 11:03  target\src\example\
............此处省略1个文件信息