所谓好记性不如烂笔头，为了以防忘记，才写下这篇博客，废话不多。。
异步树：
tips: 可以采用easyui里的原始数据格式，也可以采用扁平化的数据格式。
使用场景： 当菜单模块数量庞大或者无限极，最好使用异步树，单节点展开访问后台，返回对应的子菜单。
必须要件： 只需要一个URL即可
前台核心JS：
如果菜单比较少，也可以用异步树一次性加载 全部展开，把onLoadSuccess这段注释打开即可
后台Servlet:
@Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String key = req.getParameter("id"); DbUtil db= new DbUtil(); Connection conn = null; List tree = new ArrayList (); if(StringUtil.isEmpty(key)){ try { conn = db.getCon(); PreparedStatement ps = conn.prepareStatement("SELECT id,title FROM db_menus WHERE pid = 0"); ResultSet rs= ps.executeQuery(); while(rs.next()){ EasyuiTreeNode node = new EasyuiTreeNode(); node.setId(rs.getString("id")); node.setState(existsText(conn,rs.getString("id"))? "closed":"open"); //如果想默认都是以文件夹形式显示，这样设置：node.setState("closed"); node.setTitle(rs.getString("title")); tree.add(node); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ try { conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }else{ try { conn = db.getCon(); PreparedStatement ps = conn.prepareStatement("SELECT id,title FROM db_menus WHERE pid = ?"); ps.setString(1, key); ResultSet rs= ps.executeQuery(); while(rs.next()){ EasyuiTreeNode node = new EasyuiTreeNode(); node.setId(rs.getString("id")); node.setState((existsText(conn,key)? "open":"closed")); node.setTitle(rs.getString("title")); tree.add(node); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ try { conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } String json = JSON.toJSONString(tree); resp.setContentType("text/html;charset=utf-8"); PrintWriter out=resp.getWriter(); out.println(json); out.flush(); out.close(); } private boolean existsText(Connection conn,String pid) throws SQLException{ PreparedStatement ps = conn.prepareStatement("SELECT COUNT(1) num FROM db_menus WHERE pid = ?"); boolean isClosed = true; ps.setString(1, pid); ResultSet rs = ps.executeQuery(); if(rs.next()){ String count = rs.getString("num"); if("0".equals(count)){ isClosed = false; } } return isClosed; }} 同步树：
tips:这里采用扁平化的json格式实现，easyui tree 模仿ztree 使用扁平化加载json 原文链接：
使用场景：菜单模块少 可以采用（PS：跟异步树一次性加载区别在于：同步树一次性加载 请求post一次,异步树因为采用了递归展开，请求post N次）
必须条件：数据格式要配制成ztree的数据格式（id,pid）
前台JS代码：
后台Servlet代码：
@Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //String key = req.getParameter("id"); DbUtil db= new DbUtil(); Connection conn = null; List tree = new ArrayList (); try { conn = db.getCon(); PreparedStatement ps = conn.prepareStatement("SELECT id,pid,title FROM db_menus"); ResultSet rs= ps.executeQuery(); while(rs.next()){ EasyuiTreeNode node = new EasyuiTreeNode(); node.setId(rs.getString("id")); node.setPid(rs.getString("pid")); node.setState(existsText(conn,rs.getString("id"))? "closed":"open"); //如果想默认都是以文件夹形式显示，这样设置：node.setState("closed"); node.setTitle(rs.getString("title")); tree.add(node); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ try { conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } String json = JSON.toJSONString(tree); System.out.println(json); resp.setContentType("text/html;charset=utf-8"); PrintWriter out=resp.getWriter(); out.println(json); out.flush(); out.close(); } private boolean existsText(Connection conn,String pid) throws SQLException{ PreparedStatement ps = conn.prepareStatement("SELECT COUNT(1) num FROM db_menus WHERE pid = ?"); boolean isClosed = true; ps.setString(1, pid); ResultSet rs = ps.executeQuery(); if(rs.next()){ String count = rs.getString("num"); if("0".equals(count)){ isClosed = false; } } return isClosed; } 附上数据脚本：
CREATE TABLE db_menus(id BIGINT(20) NOT NULL AUTO_INCREMENT,pid BIGINT(20) NOT NULL,title VARCHAR(100) DEFAULT NULL,url VARCHAR(100) DEFAULT NULL,PRIMARY KEY (id ))ENGINE=INNODB DEFAULT CHARSET=utf8 COMMENT='菜单表'DROP TABLE db_menusINSERT INTO db_menus VALUES(NULL,0,'项目管理',NULL);INSERT INTO db_menus VALUES(NULL,0,'任务管理',NULL);INSERT INTO db_menus VALUES(NULL,0,'考勤管理',NULL);INSERT INTO db_menus VALUES(NULL,0,'报销管理',NULL);INSERT INTO db_menus VALUES(NULL,0,'绩效管理',NULL);INSERT INTO db_menus VALUES(NULL,0,'通讯录管理',NULL);INSERT INTO db_menus VALUES(NULL,1,'个人周报查询',NULL);INSERT INTO db_menus VALUES(NULL,1,'项目周报查询',NULL);INSERT INTO db_menus VALUES(NULL,1,'个人周报填写',NULL);INSERT INTO db_menus VALUES(NULL,1,'项目周报填写',NULL);INSERT INTO db_menus VALUES(NULL,2,'我的任务',NULL);INSERT INTO db_menus VALUES(NULL,2,'指定任务',NULL);INSERT INTO db_menus VALUES(NULL,3,'派出申请',NULL);INSERT INTO db_menus VALUES(NULL,3,'加班申请',NULL);INSERT INTO db_menus VALUES(NULL,3,'请假申请',NULL);INSERT INTO db_menus VALUES(NULL,4,'我的报销',NULL);INSERT INTO db_menus VALUES(NULL,4,'报销审批',NULL);INSERT INTO db_menus VALUES(NULL,5,'绩效考核填报',NULL);INSERT INTO db_menus VALUES(NULL,5,'绩效考核审核',NULL);INSERT INTO db_menus VALUES(NULL,6,'通讯录',NULL);