标签：name NodeVo pid list children 树形 id
“树”这个结构，在计算机中应该是无处不在的。例如文件目录树，数据库树索引，组织机构树等等。对于JavaWeb开发工程师来说，比较常见的有菜单树，权限树，组织机构树等。这些树形结构的每一个节点通常是存在数据库表中的，并且每一个节点都是一条独立的数据。如下，这里规定pid为null的时候，为根节点
那么如何将这样的列表数据封装为树形结构的数据呢？结构如下
[
{
"id": "0",
"pid": null,
"name": "全国",
"children": [
{
"id": "1",
"pid": "0",
"name": "广东省",
"children": [
{
"id": "4",
"pid": "1",
"name": "佛山市",
"children": [
]
},
{
"id": "5",
"pid": "1",
"name": "汕头市",
"children": [
]
},
{
"id": "6",
"pid": "1",
"name": "东莞市",
"children": [
]
}
]
},
{
"id": "2",
"pid": "0",
"name": "湖北省",
"children": [
{
"id": "7",
"pid": "2",
"name": "黄冈市",
"children": [
]
},
{
"id": "8",
"pid": "2",
"name": "宜昌市",
"children": [
]
},
{
"id": "9",
"pid": "2",
"name": "襄阳市",
"children": [
]
}
]
},
{
"id": "3",
"pid": "0",
"name": "河南省",
"children": [
{
"id": "10",
"pid": "3",
"name": "洛阳市",
"children": [
]
},
{
"id": "11",
"pid": "3",
"name": "开封市",
"children": [
]
},
{
"id": "12",
"pid": "3",
"name": "新乡市",
"children": [
]
}
]
}
]
}
]
代码如何
1，节点类
package net.sunmonkey.datatotree;
import java.util.LinkedList;
import java.util.List;
/**
* 树结构节点对象类
* @author Wenqin Cheng
*/
public class NodeVo {
private String id;
private String pid;
private String name;
private List<NodeVo> children;
public NodeVo() {
children = new LinkedList<>();
}
public NodeVo(String id, String pid, String name) {
this.id = id;
this.pid = pid;
this.name = name;
this.children = new LinkedList<>();
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getPid() {
return pid;
}
public void setPid(String pid) {
this.pid = pid;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<NodeVo> getChildren() {
return children;
}
public void setChildren(List<NodeVo> children) {
this.children = children;
}
@Override
public String toString() {
return "NodeVo{" +
"id='" + id + '\'' +
", pid='" + pid + '\'' +
", name='" + name + '\'' +
", children=" + children +
'}';
}
}
2，转换工具类
package net.sunmonkey.datatotree;
import java.util.LinkedList;
import java.util.List;
/**
* id，pid的列表数据转化为树形结构数据
* @author Wenqin Cheng
*/
public class ConvertUtil {
public static List<NodeVo> getTreeData(List<NodeVo> list) {
List<NodeVo> tree = new LinkedList<>();
if(null != list && !list.isEmpty()){
for(NodeVo nodeVo: list){
addToTreeNodeList(list, nodeVo);
}
for (NodeVo nodeVo: list){
if(null == nodeVo.getPid()){
tree.add(nodeVo);
}
}
}
return tree;
}
private static void addToTreeNodeList(final List<NodeVo> nodeVoList, NodeVo treeNodeVo){
if(null != nodeVoList && !nodeVoList.isEmpty()){
for(NodeVo parentNodeVo: nodeVoList){
if(parentNodeVo.getId().equals(treeNodeVo.getPid())){
List<NodeVo> children = parentNodeVo.getChildren();
boolean flag = true;
for(NodeVo node: children){
if(treeNodeVo.getId().equals(node.getId())){
flag = false;
}
}
if(flag){
children.add(treeNodeVo);
}
break;
}else{
addToTreeNodeList(parentNodeVo.getChildren(), treeNodeVo);
}
}
}
}
}
3，测试主方法
package net.sunmonkey.datatotree;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.LinkedList;
import java.util.List;
/**
* 主方法
* @author Wenqin Cheng
*/
public class MainClass {
static ObjectMapper objectMapper = new ObjectMapper();
public static void main(String[] args) throws Exception {
List<NodeVo> list = new LinkedList<>();
list.add(new NodeVo("0", null, "全国"));
list.add(new NodeVo("1", "0", "广东省"));
list.add(new NodeVo("2", "0", "湖北省"));
list.add(new NodeVo("3", "0", "河南省"));
list.add(new NodeVo("4", "1", "佛山市"));
list.add(new NodeVo("5", "1", "汕头市"));
list.add(new NodeVo("6", "1", "东莞市"));
list.add(new NodeVo("7", "2", "黄冈市"));
list.add(new NodeVo("8", "2", "宜昌市"));
list.add(new NodeVo("9", "2", "襄阳市"));
list.add(new NodeVo("10", "3", "洛阳市"));
list.add(new NodeVo("11", "3", "开封市"));
list.add(new NodeVo("12", "3", "新乡市"));
System.out.println("转换前数据：");
System.out.println(objectMapper.writeValueAsString(list));
List<NodeVo> result = ConvertUtil.getTreeData(list);
System.out.println("转换后数据：");
System.out.println(objectMapper.writeValueAsString(result));
}
}
标签：name,NodeVo,pid,list,children,树形,id 来源： https://www.cnblogs.com/chengwenqin/p/14125257.html
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