1.构建一个树形结构的实体类TreeBean
public class TreeBean implements Serializable {
private static final long serialVersionUID = 1L;
/*id和pid必须赋值，level看自己有没有这个字段，otherParameter装一些其他参数，比如name，key-value键值对的形式*/
/*将你从数据库查出来的集合循环，然后对每一行数据进行赋值转换成TreeBean结构，调用TreeUtils工具即可得到树形结构列表*/
private Object id;//id
private Object pid;//pid
private Object level;//级别
private Map otherParameter;//其他参数，需要展示的参数,比如name之类的
/*---------------------------------下面这些不需要你赋值-------------------------------------------*/
private Boolean hasChildren;//是否含有下一级
private List children;//包含的子节点
private Integer childrenSize;//子节点的集合大小
}
2.构造树形结构的方法
/**
* 树形结构
* @param assetsSorts 查询出集合
* @param assetsSortId 顶级节点id
* @return
*/
public List buildTree(List assetsSorts,Long assetsSortId) {
ArrayList treeBeans = new ArrayList<>();
List treeBeans1 = new ArrayList<>();
if(!CollectionUtils.isEmpty(assetsSorts)){
Long topId = 1L;
TreeBean assetsSortBean =null;
for(AssetsSort assetsSort:assetsSorts){
TreeBean treeBean = new TreeBean();
treeBean.setId(assetsSort.getAssetsSortId());
treeBean.setPid(assetsSort.getParentId());
Map parameter = new HashMap<>();
parameter.put("assetsSortName", assetsSort.getAssetsSortName());
parameter.put("assetsSortNames", assetsSort.getAssetsSortNames());
parameter.put("parentIds", assetsSort.getParentIds());
parameter.put("createBy", assetsSort.getCreateBy());
parameter.put("createTime", ObjectUtils.isEmpty(assetsSort.getCreateTime()) ? "":DateUtils.parseDateToStr("yyyy-MM-dd hh:mm:ss",assetsSort.getCreateTime()));
parameter.put("updateBy", assetsSort.getUpdateBy());
parameter.put("updateTime", ObjectUtils.isEmpty(assetsSort.getUpdateTime()) ? "":DateUtils.parseDateToStr("yyyy-MM-dd hh:mm:ss",assetsSort.getUpdateTime()));
parameter.put("deleteFlag", assetsSort.getDeleteFlag());
treeBean.setOtherParameter(parameter);
treeBeans.add(treeBean);
//拿到顶级节点
if ((!ObjectUtils.isEmpty(assetsSortId)&&NumberUtil.compare(assetsSortId,assetsSort.getAssetsSortId())==0)
|| NumberUtil.compare(topId,assetsSort.getAssetsSortId())==0){
assetsSortBean = treeBean;
}
}
if(!ObjectUtils.isEmpty(assetsSortId)){
topId = assetsSortId;
}
treeBeans1 = TreeUtils.buildByRecursive(treeBeans, topId,assetsSortBean);
}
return treeBeans1;
}
3.快速建树的工具类
import cn.hutool.core.util.NumberUtil;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.lephips.utils.bean.TreeBean;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
*
* * @projectName vcsrm-parent
* * @title TreeUtils
* * @package com.clfps.utils
* * @description 树形结构utils
* * @author IT_CREAT
* * @date 2019 2019/7/1 15:39
* * @version V1.0.0
*
*/
public class TreeUtils {
/**
* 使用递归方法建树
* @param
* @return
*/
public static List buildByRecursive(List treeBeans, Long topId ,TreeBean topTreeBean) {
List trees = new ArrayList<>();
TreeBean treeBeanTop = null;
for (TreeBean treeBean : treeBeans) {
if (0 == NumberUtil.compare(treeBean.getPid(),topId)) {
Long level = 1L;
if(!ObjectUtils.isEmpty(topTreeBean) && 0 == NumberUtil.compare(topTreeBean.getId(), topId)){
level = 2L;
}
TreeBean treeBean2 = findChildren(treeBean,treeBeans,level);
if(CollectionUtils.isEmpty(treeBean2.getChildren())){
treeBean2.setHasChildren(false);
treeBean2.setLevel(level);
}else {
treeBean2.setHasChildren(true);
treeBean2.setLevel(level);
treeBean2.setChildrenSize((long) treeBean2.getChildren().size());
}
trees.add(treeBean2);
}else if(!ObjectUtils.isEmpty(topTreeBean) && 0 == NumberUtil.compare(treeBean.getId(), topId)){
treeBeanTop = treeBean;
}
}
if(!ObjectUtils.isEmpty(treeBeanTop)){
treeBeanTop.setChildren(trees)
.setChildrenSize((long) trees.size())
.setHasChildren(true)
.setLevel(1L);
trees = new ArrayList<>();
trees.add(treeBeanTop);
}
return trees;
}
/**
* 递归查找子节点
* @param
* @return
*/
private static TreeBean findChildren(TreeBean treeBean,List treeBeans,Long level) {
for (TreeBean it : treeBeans) {
if(0 == NumberUtil.compare(treeBean.getId(), it.getPid())) {
if (treeBean.getChildren() == null) {
treeBean.setChildren(new ArrayList<>());
}
TreeBean treeBean2 = findChildren(it,treeBeans,level+1);
if(!CollectionUtils.isEmpty(treeBean2.getChildren())){
treeBean2.setHasChildren(true);
treeBean2.setChildrenSize((long) treeBean.getChildren().size());
treeBean2.setLevel(level+1);
}else if(treeBean2.getChildren() == null || treeBean2.getChildren().size() == 0){
treeBean2.setHasChildren(false);
treeBean2.setLevel(level+1);
}
treeBean.getChildren().add(treeBean2);
}
}
return treeBean;
}
public static void main(String[] args) {
TreeBean treeBean = new TreeBean();
treeBean.setId(1L);
treeBean.setPid(6000L);
// treeBean.setLevel(1);
Map parameter = new HashMap<>();
parameter.put("name", "sadasda");
parameter.put("nameEn", "sadasda");
parameter.put("namePinyin", "sadasda");
parameter.put("code", "sadasda");
treeBean.setOtherParameter(parameter);
TreeBean treeBean2 = new TreeBean();
treeBean2.setId(2L);
treeBean2.setPid(6000L);
// treeBean2.setLevel(1);
Map parameter2 = new HashMap<>();
parameter.put("name", "sadasda");
parameter.put("nameEn", "sadasda");
parameter.put("namePinyin", "sadasda");
parameter.put("code", "sadasda");
treeBean2.setOtherParameter(parameter);
TreeBean treeBean3 = new TreeBean();
treeBean3.setId(3L);
treeBean3.setPid(1L);
// treeBean3.setLevel(2);
Map parameter3 = new HashMap<>();
parameter.put("name", "sadasda");
parameter.put("nameEn", "sadasda");
parameter.put("namePinyin", "sadasda");
parameter.put("code", "sadasda");
treeBean3.setOtherParameter(parameter);
TreeBean treeBean4 = new TreeBean();
treeBean4.setId(4L);
treeBean4.setPid(1L);
// treeBean4.setLevel(2);
Map parameter4 = new HashMap<>();
parameter.put("name", "sadasda");
parameter.put("nameEn", "sadasda");
parameter.put("namePinyin", "sadasda");
parameter.put("code", "sadasda");
treeBean4.setOtherParameter(parameter);
TreeBean treeBean5 = new TreeBean();
treeBean5.setId(5L);
treeBean5.setPid(3L);
// treeBean5.setLevel(3);
Map parameter5 = new HashMap<>();
parameter.put("name", "sadasda");
parameter.put("nameEn", "sadasda");
parameter.put("namePinyin", "sadasda");
parameter.put("code", "sadasda");
treeBean5.setOtherParameter(parameter);
List treeBeans = new ArrayList<>();
treeBeans.add(treeBean);
treeBeans.add(treeBean2);
treeBeans.add(treeBean3);
treeBeans.add(treeBean4);
treeBeans.add(treeBean5);
System.out.println(buildByRecursive(treeBeans,6000L,null));
ObjectMapper objectMapper = new ObjectMapper();
try {
System.out.println(objectMapper.writeValueAsString(buildByRecursive(treeBeans,1L,null)));
} catch (JsonProcessingException e) {
e.printStackTrace();
}
}
}
