Java实现树形结构的数据转Json格式
在项目中难免会用到树形结构，毕竟这是一种常用的组织架构。楼主这里整理了两个实现的版本，可以直接拿来使用，非常方便。
楼主没有单独建项目，直接在以前的一个Demo上实现的。第一种，看下面代码：
package com.johanChan.WebSocket.utils;import com.alibaba.fastjson.JSON;import java.util.ArrayList;
import java.util.List;//图层结构
public class TreeBuilder {List<Node> nodes = new ArrayList<>();public String buildTree(List<Node> nodes) {TreeBuilder treeBuilder = new TreeBuilder(nodes);return treeBuilder.buildJSONTree();}public TreeBuilder() {}public TreeBuilder(List<Node> nodes) {super();this.nodes = nodes;}// 构建JSON树形结构public String buildJSONTree() {List<Node> nodeTree = buildTree();String jsonStr = JSON.toJSONString(nodeTree);return jsonStr;}// 构建树形结构public List<Node> buildTree() {List<Node> treeNodes = new ArrayList<>();List<Node> rootNodes = getRootNodes();for (Node rootNode : rootNodes) {buildChildNodes(rootNode);treeNodes.add(rootNode);}return treeNodes;}// 递归子节点public void buildChildNodes(Node node) {List<Node> children = getChildNodes(node);if (!children.isEmpty()) {for (Node child : children) {buildChildNodes(child);}node.setChildren(children);}}// 获取父节点下所有的子节点public List<Node> getChildNodes(Node pnode) {List<Node> childNodes = new ArrayList<>();for (Node n : nodes) {if (pnode.getId().equals(n.getParentId())) {childNodes.add(n);}}return childNodes;}// 判断是否为根节点public boolean rootNode(Node node) {boolean isRootNode = true;for (Node n : nodes) {if (node.getParentId().equals(n.getId())) {isRootNode = false;break;}}return isRootNode;}// 获取集合中所有的根节点public List<Node> getRootNodes() {List<Node> rootNodes = new ArrayList<>();for (Node n : nodes) {if (rootNode(n)) {rootNodes.add(n);}}return rootNodes;}public static class Node {private Integer id;private Integer parentId;private String name;private String code;private Integer level;private List<Node> children;public Node() {}public Node(Integer id,Integer parentId,String name,String code,Integer level){super();this.id = id;this.parentId = parentId;this.name = name;this.code = code;this.level = level;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public Integer getParentId() {return parentId;}public void setParentId(Integer parentId) {this.parentId = parentId;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getCode() {return code;}public void setCode(String code) {this.code = code;}public Integer getLevel() {return level;}public void setLevel(Integer level) {this.level = level;}public List<Node> getChildren() {return children;}public void setChildren(List<Node> children) {this.children = children;}}
}
看起来很长对吗？没关系，直接copy一下就可以使用。首先生成一个树形结构的数据：
public static List<TreeBuilder.Node> buildNode(){List<TreeBuilder.Node> nodeList = new ArrayList<>();TreeBuilder.Node node = new TreeBuilder.Node(0,-1,"地球","WORD",1);TreeBuilder.Node node1 = new TreeBuilder.Node(1,0,"中国","CHN",1);TreeBuilder.Node node2 = new TreeBuilder.Node(2,1,"华北区域","A",2);TreeBuilder.Node node3 = new TreeBuilder.Node(3,1,"华南区域","B",2);TreeBuilder.Node node4 = new TreeBuilder.Node(4,1,"华东区域","C",2);TreeBuilder.Node node5 = new TreeBuilder.Node(5,1,"华西区域","D",2);TreeBuilder.Node node6 = new TreeBuilder.Node(6,1,"华中区域","E",2);TreeBuilder.Node node7 = new TreeBuilder.Node(7,6,"河南","豫",3);TreeBuilder.Node node8 = new TreeBuilder.Node(8,6,"湖北","鄂",3);TreeBuilder.Node node9 = new TreeBuilder.Node(9,6,"湖南","湘",3);TreeBuilder.Node node10 = new TreeBuilder.Node(10,6,"江西","赣",3);TreeBuilder.Node node11 = new TreeBuilder.Node(11,7,"郑州","豫A",4);TreeBuilder.Node node12 = new TreeBuilder.Node(12,7,"开封","豫B",4);TreeBuilder.Node node13 = new TreeBuilder.Node(13,7,"洛阳","豫C",4);TreeBuilder.Node node14 = new TreeBuilder.Node(14,7,"南阳","豫R",4);TreeBuilder.Node node15 = new TreeBuilder.Node(15,11,"金水区","豫A-1",5);nodeList.add(node);nodeList.add(node1);nodeList.add(node2);nodeList.add(node3);nodeList.add(node4);nodeList.add(node5);nodeList.add(node6);nodeList.add(node7);nodeList.add(node8);nodeList.add(node9);nodeList.add(node10);nodeList.add(node11);nodeList.add(node12);nodeList.add(node13);nodeList.add(node14);nodeList.add(node15);return nodeList;}
然后调用new TreeBuilder().buildTree(nodeList)就可以返回json格式的字符串了：
package com.johanChan.WebSocket.controller;import com.alibaba.fastjson.JSON;
import com.johanChan.WebSocket.utils.CommonUtils;
import com.johanChan.WebSocket.utils.TreeBuilder;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;import java.util.List;@Controller
public class TreeController {List<TreeBuilder.Node> nodeList ;{nodeList = CommonUtils.buildNode();}@ResponseBody@RequestMapping("/getTreeJson")public String getTreeJson() {
// List<TreeBuilder.Node> nodeList = CommonUtils.buildNode();String result = new TreeBuilder().buildTree(nodeList);return result; } }
启动项目，访问/getTreeJson可以看到，页面返回了json字符串：
整理后如下：
[{"children":[{"children":[{"code":"A","id":2,"level":2,"name":"华北区域","parentId":1},{"code":"B","id":3,"level":2,"name":"华南区域","parentId":1},{"code":"C","id":4,"level":2,"name":"华东区域","parentId":1},{"code":"D","id":5,"level":2,"name":"华西区域","parentId":1},{"children":[{"children":[{"children":[{"code":"豫A-1","id":15,"level":5,"name":"金水区","parentId":11}],"code":"豫A","id":11,"level":4,"name":"郑州","parentId":7},{"code":"豫B","id":12,"level":4,"name":"开封","parentId":7},{"code":"豫C","id":13,"level":4,"name":"洛阳","parentId":7},{"code":"豫R","id":14,"level":4,"name":"南阳","parentId":7}],"code":"豫","id":7,"level":3,"name":"河南","parentId":6},{"code":"鄂","id":8,"level":3,"name":"湖北","parentId":6},{"code":"湘","id":9,"level":3,"name":"湖南","parentId":6},{"code":"赣","id":10,"level":3,"name":"江西","parentId":6}],"code":"E","id":6,"level":2,"name":"华中区域","parentId":1}],"code":"CHN","id":1,"level":1,"name":"中国","parentId":0}],"code":"WORD","id":0,"level":1,"name":"地球","parentId":-1}
]
第一种方法完成，下面是第二种实现，首先建立一个类：
package com.johanChan.WebSocket.utils;import java.util.ArrayList;
import java.util.List;public class Tree<T> {/*** 节点ID*/private Integer id;/*** 显示节点文本*/private String text;/*** 父ID*/private Integer parentId;private Integer level;/*** 节点的子节点*/// private List<Tree<T>> nodes = new ArrayList<Tree<T>>();private List<Tree<T>> nodes = null;public Tree() {}public Tree(Integer id,Integer parentId,String text,Integer level){super();this.id = id;this.text = text;this.parentId = parentId;this.level = level;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getText() {return text;}public void setText(String text) {this.text = text;}public Integer getParentId() {return parentId;}public void setParentId(Integer parentId) {this.parentId = parentId;}public Integer getLevel() {return level;}public void setLevel(Integer level) {this.level = level;}public List<Tree<T>> getNodes() {if(nodes==null){nodes = new ArrayList<Tree<T>>();}return nodes;}public void setNodes(List<Tree<T>> nodes) {this.nodes = nodes;}}
然后对Tree进行排序：
package com.johanChan.WebSocket.utils;import java.util.ArrayList;
import java.util.List;public class BuildTree {public static <T> List<Tree<T>> build(List<Tree<T>> nodes) {if (nodes == null) {return null;}List<Tree<T>> topNodes = new ArrayList<>();for (Tree<T> children : nodes) {String pid = children.getParentId();if (pid.equals(children.getId() )) {topNodes.add(children);continue;}for (Tree<T> parent : nodes) {String id = parent.getId();if (id != null && id.equals(pid)) {parent.getNodes().add(children);}}}return topNodes;}}
然后生成数据：
public static List<Tree<TreeBuilder.Node>> buildTree(){List<Tree<TreeBuilder.Node>> treeList = new ArrayList<>();Tree<TreeBuilder.Node> tree = new Tree<TreeBuilder.Node>(0,0,"地球",1);Tree tree1 = new Tree(1,0,"中国",1);Tree tree2 = new Tree(2,1,"华北区域",2);Tree tree3 = new Tree(3,1,"华南区域",2);Tree tree4 = new Tree(4,1,"华东区域",2);Tree tree5 = new Tree(5,1,"华西区域",2);Tree tree6 = new Tree(6,1,"华中区域",2);Tree tree7 = new Tree(7,6,"河南",3);Tree tree8 = new Tree(8,6,"湖北",3);Tree tree9 = new Tree(9,6,"湖南",3);Tree tree10 = new Tree(10,6,"江西",3);Tree tree11 = new Tree(11,7,"郑州",4);Tree tree12 = new Tree(12,7,"开封",4);Tree tree13 = new Tree(13,7,"洛阳",4);Tree tree14 = new Tree(14,7,"南阳",4);Tree tree15 = new Tree(15,11,"金水区",5);treeList.add(tree);treeList.add(tree1);treeList.add(tree2);treeList.add(tree3);treeList.add(tree4);treeList.add(tree5);treeList.add(tree6);treeList.add(tree7);treeList.add(tree8);treeList.add(tree9);treeList.add(tree10);treeList.add(tree11);treeList.add(tree12);treeList.add(tree13);treeList.add(tree14);treeList.add(tree15);return treeList;}
调用方法：
package com.johanChan.WebSocket.controller;import com.alibaba.fastjson.JSON;
import com.johanChan.WebSocket.utils.BuildTree;
import com.johanChan.WebSocket.utils.CommonUtils;
import com.johanChan.WebSocket.utils.Tree;
import com.johanChan.WebSocket.utils.TreeBuilder;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;import java.util.List;@Controller
public class TreeController {List<TreeBuilder.Node> nodeList ;List<Tree<TreeBuilder.Node>> treeList;{nodeList = CommonUtils.buildNode();treeList = CommonUtils.buildTree();}@ResponseBody@RequestMapping("/getTreeJson")public String getTreeJson() {
// List<TreeBuilder.Node> nodeList = CommonUtils.buildNode();
// String result = CommonUtils.buildTree(nodeList);List<Tree<TreeBuilder.Node>> resultList = BuildTree.build(treeList);String result = JSON.toJSONString(resultList);return result;}}
返回数据如下：
整理后：
View Code
OK！以上两种方法都比较有通用性，把自己的数据整理后调用就可以了。
