2、tree组件工具类的实现思路
入门之Tree后台实现 2、tree组件工具类的实现思路 正式从数据库拿数据写 代码2总结：
tree的组件简介
静态的html方式：
缺点：如果树形结构复杂，层级较多，那么c:以及c:if的嵌套就会比较多，不方便编码
通过java代码以及jackson 的jar包来生产对应的格式数据（能够格式这么来）查询数据库，拿到需要的数据TreeVo，BuildTreeBuildTree核心思想两个循环外层循环默认遍历的就是父节点内层循环默认遍历的就是子节点只要父节点的id=子节点的父id，那么就是父子关系，子节点的父id，那么子节点就应该添加到父节点的children中
可在D:\java课程\数据库\1、入门\资料（我自己存放的外置）中找到APl文件
打开 1.5 版 API 中文版 (Made By )文件，找到如图，查看tree有关资料。
案例1：
无论用不用，先添加了。
在D:\java课程\数据库\1、入门\资料\--1.5.1\demo\tree找到一个最基础的布局格式basic.html
在复制它的源代码,
就称下代码代号为1号代码
- My Documents
- Photos
- Friend
- Wife
- Company
- Program Files
- Intel
- Java
- Microsoft Office
- Games
- index.html
- about.html
- welcome.html
放入jsp显示页面里去
运行
如果这些数据来自数据库必须加很多的if条件，你要判断谁到底是谁的父亲，因级别，里要套，有儿子又要套，这样非常麻烦。所以框架的作者就想到了一个方法，他省略了一个过程，他帮你把这个东西写好了，你直接提供数据就行了，提供他指定格式的数据就可以了。具体他这么实现这里不说，他是通过实现的，想了解可以去csdn找下。本人也不了解。
找到四行代码
他就用这四行代码解决c： 判断，嵌套的一个问题。
用这个代码取代一号代码
1.
等于一号代码的效果
在 D:\java课程\数据库\1、入门\资料\--1.5.1\demo\tree 中找到.json
创建一个index.js文件
2.$('#tt').tree({ 3. url:'tree_data.json' 4. });
用一下语句调用index.js,index.js调用.json中的格式
运行结果：
2、tree组件工具类的实现思路 预热
思考：如何从数据库得到数据实现上面效果？
方案
先做一个简单测试来得知如何插入数据：
代码
实体类
package com.yinbangchi.vo;import java.util.ArrayList;import java.util.List;public class TreeVo {private String id;private String text;private List children=new ArrayList();private String pid;public String getId() {return id;}public void setId(String id) {this.id = id;}public String getText() {return text;}public void setText(String text) {this.text = text;}public List getChildren() {return children;}public void setChildren(List children) {this.children = children;}public String getPid() {return pid;}public void setPid(String pid) {this.pid = pid;}public TreeVo() {super();}public TreeVo(String id, String text, String pid) {super();this.id = id;this.text = text;this.pid = pid;}public TreeVo(String id, String text, List children, String pid) {super();this.id = id;this.text = text;this.children = children;this.pid = pid;}@Overridepublic String toString() {return "TreeVo [id=" + id + ", text=" + text + ", children=" + children + ", pid=" + pid + "]";} }
测试类
package com.yinbangchi.vo;import java.util.List;import org.junit.Test;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.ObjectMapper;public class TreeVoTest {@Testpublic void test() throws JsonProcessingException {TreeVo treeVoOneLevel=new TreeVo("1","my documents","-1");TreeVo treeVoOneLeve11=new TreeVo("11","photos","1");TreeVo treeVoOneLeve12=new TreeVo("12","program files","1");TreeVo treeVoOneLeve13=new TreeVo("13","index.html","1");TreeVo treeVoOneLeve14=new TreeVo("14","about.html","1");TreeVo treeVoOneLeve15=new TreeVo("15","welcome.html","1");List parent=treeVoOneLevel.getChildren();parent.add(treeVoOneLeve11);parent.add(treeVoOneLeve12);parent.add(treeVoOneLeve13);parent.add(treeVoOneLeve14);parent.add(treeVoOneLeve15);ObjectMapper om=new ObjectMapper();String jsonStr = om.writeValueAsString(treeVoOneLevel);System.out.println(jsonStr);}}
运行结果：
链接
到这个链接: （json解析格式化工具）
如图：
代码2：
{"id": "1", ——父亲"text": "my documents","children": [{"id": "11","text": "photos",——儿子"children": [],"pid": "1"}, {"id": "12","text": "program files",——二儿子"children": [],"pid": "1"}, {"id": "13","text": "index.html",——三儿子"children": [],"pid": "1"}, {"id": "14","text": "about.html",——四儿子"children": [],"pid": "1"}, {"id": "15","text": "welcome.html",——五儿子"children": [],"pid": "1"}],"pid": "-1"}
这些数据都是手写，现在正式敲代码。
正式从数据库拿数据写 代码
实体类
package com.yinbangchi.entity;public class Permission{private long id;private String name;private String description;private String url;private long pid;private int ismenu;private long displayno;public long getId() {return id;}public void setId(long id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}public long getPid() {return pid;}public void setPid(long pid) {this.pid = pid;}public int getIsmenu() {return ismenu;}public void setIsmenu(int ismenu) {this.ismenu = ismenu;}public long getDisplayno() {return displayno;}public void setDisplayno(long displayno) {this.displayno = displayno;}public Permission() {super();}public Permission(long id, String name, String description, String url, long pid, int ismenu, long displayno) {this.id = id;this.name = name;this.description = description;this.url = url;this.pid = pid;this.ismenu = ismenu;this.displayno = displayno;}@Overridepublic String toString() {return "Permission [id=" + id + ", name=" + name + ", description=" + description + ", url=" + url + ", pid="+ pid + ", ismenu=" + ismenu + ", displayno=" + displayno + "]";}
类
package com.yinbangchi.dao;import java.util.List;import com.yinbangchi.entity.Permission;import com.yinbangchi.uilt.BaseDao;import com.yinbangchi.uilt.PageBean;public class PermissionDao extends BaseDao {
调用方法
public List list(Permission permission,PageBean pageBean) throws Exception{String sql="select *from t_easyui_Permission ";return super.executeQuery(Permission.class, sql, pageBean);}
测试：
public static void main(String[] args) throws Exception {PermissionDao di=new PermissionDao();List list = di.list(null, null);for (Permission s : list) {System.out.println("星系"+s);}}}}
运行效果：
我们要做到的差不多的效果
代码2
class {
/*** 默认0为顶级节点* @param nodes* @param * @return*/
public static TreeVo build(List> nodes) {if (nodes == null) {return null;}
存放顶级节点（二级节点）的容器
List> topNodes = new ArrayList>();for (TreeVo children : nodes) {String pid = children.getParentId();if (pid == null || "0".equals(pid)) {topNodes.add(children);
如果是顶级节点，那么结束当前循环，继续下一次循环。
continue;}for (TreeVo parent : nodes) {String id = parent.getId();
判断二级节点父pid是否等于一级阶段的id
if (id != null && id.equals(pid)) {parent.getChildren().add(children);children.setHasParent(true);parent.setChildren(true);continue;}}}
考虑到一个问题，数据库中没有顶级节点（一级节点）
TreeVo root = new TreeVo();if (topNodes.size() == 1) {
数据库有顶级节点这条数据
root = topNodes.get(0);} else {
数据库中没顶级结点这条数据，那么通过代码创建
root.setId("000");root.setParentId("-1");root.setHasParent(false);root.setChildren(true);root.setChecked(true);root.setChildren(topNodes);root.setText("顶级节点");Map state = new HashMap<>(16);state.put("opened", true);root.setState(state);}return root;
}/*** 指定idparam为顶级节点* @param nodes* @param idParam* @param * @return*/
public static List> buildList(List> nodes, String idParam) {if (nodes == null) {return null;}List> topNodes = new ArrayList>();for (TreeVo children : nodes) {String pid = children.getParentId();if (pid == null || idParam.equals(pid)) {topNodes.add(children);continue;}for (TreeVo parent : nodes) {String id = parent.getId();if (id != null && id.equals(pid)) {parent.getChildren().add(children);children.setHasParent(true);parent.setChildren(true);continue;}}}return topNodes;
}}
测试一下
void main([] args) {
PermissionDao di=new PermissionDao();List list = di.list(null, null);
通过工具类完成指定的格式的输出
List> nodes=new ArrayList>();
的格式是不满足的tree主键，战线的数据格式
目的:将List转换成list
实现:将List得到的单个转换，
TreeVo treeVo=null;for (Permission s : list) {treeVo=new TreeVo<>();treeVo.setId(s.getId()+"");treeVo.setText(s.getName()+"");treeVo.setParentId(s.getPid()+"");Map attributes=new HashMap();attributes.put("self", s);treeVo.setAttributes(attributes);nodes.add(treeVo);}TreeVo parent=BuildTree.build(nodes);ObjectMapper on=new ObjectMapper();String jsonstr = on.writeValueAsString(parent);System.out.println(jsonstr);}
运行结果
编译：
{"id": "000","text": "椤剁骇鑺傜偣","state": {"opened": true},"checked": true,"attributes": null,"children": [{"id": "1","text": "书籍管理","state": null,"checked": false,"attributes": {"self": {"id": 1,"name": "书籍管理","description": "书籍管理","url": null,"pid": 0,"ismenu": 1,"displayno": 0}},"children": [{"id": "2","text": "新增（crud）","state": null,"checked": false,"attributes": {"self": {"id": 2,"name": "新增（crud）","description": "书籍新增","url": "/bg/addBook.jsp","pid": 1,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "1","hasParent": true,"hasChildren": false}, {"id": "3","text": "未上架","state": null,"checked": false,"attributes": {"self": {"id": 3,"name": "未上架","description": "未上架书籍","url": "/bg/listBook1.jsp","pid": 1,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "1","hasParent": true,"hasChildren": false}, {"id": "4","text": "已上架","state": null,"checked": false,"attributes": {"self": {"id": 4,"name": "已上架","description": "已上架书籍","url": "/bg/listBook2.jsp","pid": 1,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "1","hasParent": true,"hasChildren": false}, {"id": "5","text": "已下架","state": null,"checked": false,"attributes": {"self": {"id": 5,"name": "已下架","description": "已下架书籍","url": "/bg/listBook3.jsp","pid": 1,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "1","hasParent": true,"hasChildren": false}],"parentId": "0","hasParent": false,"hasChildren": true}, {"id": "6","text": "订单管理","state": null,"checked": false,"attributes": {"self": {"id": 6,"name": "订单管理","description": "商家的订单管理模块","url": null,"pid": 0,"ismenu": 1,"displayno": 0}},"children": [{"id": "7","text": "未发货","state": null,"checked": false,"attributes": {"self": {"id": 7,"name": "未发货","description": "未发货订单","url": "/bg/listOrder1.jsp","pid": 6,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "6","hasParent": true,"hasChildren": false}, {"id": "8","text": "已发货","state": null,"checked": false,"attributes": {"self": {"id": 8,"name": "已发货","description": "已发货订单","url": "/bg/listOrder2.jsp","pid": 6,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "6","hasParent": true,"hasChildren": false}, {"id": "9","text": "已签收","state": null,"checked": false,"attributes": {"self": {"id": 9,"name": "已签收","description": "已签收订单","url": "/bg/listOrder3.jsp","pid": 6,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "6","hasParent": true,"hasChildren": false}, {"id": "14","text": "订单项","state": null,"checked": false,"attributes": {"self": {"id": 14,"name": "订单项","description": "订单明细","url": "/bg/listOrderItem.jsp","pid": 6,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "6","hasParent": true,"hasChildren": false}],"parentId": "0","hasParent": false,"hasChildren": true}, {"id": "10","text": "订单管理","state": null,"checked": false,"attributes": {"self": {"id": 10,"name": "订单管理","description": "会员的订单管理模块","url": "","pid": 0,"ismenu": 1,"displayno": 0}},"children": [{"id": "11","text": "未发货","state": null,"checked": false,"attributes": {"self": {"id": 11,"name": "未发货","description": "未发货订单","url": "/bg/listMyOrder1.jsp","pid": 10,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "10","hasParent": true,"hasChildren": false}, {"id": "12","text": "已发货","state": null,"checked": false,"attributes": {"self": {"id": 12,"name": "已发货","description": "已发货订单","url": "/bg/listMyOrder2.jsp","pid": 10,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "10","hasParent": true,"hasChildren": false}, {"id": "13","text": "已签收","state": null,"checked": false,"attributes": {"self": {"id": 13,"name": "已签收","description": "已签收订单","url": "/bg/listMyOrder3.jsp","pid": 10,"ismenu": 1,"displayno": 0}},"children": [],"parentId": "10","hasParent": true,"hasChildren": false}],"parentId": "0","hasParent": false,"hasChildren": true}],"parentId": "-1","hasParent": false,"hasChildren": true}
总结：
最近头痛，加油，坚持。不要白费之前的努力。
