封装树形数据操作工具类
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qianshijiang
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package com.zt.plat.framework.common.util.tree;
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import com.alibaba.fastjson.JSON;
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import com.zt.plat.framework.common.util.object.ObjectUtils;
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import lombok.Data;
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import java.util.*;
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import java.util.function.*;
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import java.util.stream.Collectors;
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/**
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* 树操作方法工具类
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*/
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public class TreeUtil {
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/**
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* 将list合成树
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*@param list 需要合成树的List
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*@param rootCheck 判断E中为根节点的条件，如：x->x.getPId()==-1L,x->x.getParentId()==null,x->x.getParentMenuId()==0
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*@param parentCheck 判断E中为父节点条件，如：(x,y)->x.getId().equals(y.getPId())
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*@param setSubChildren E中设置下级数据方法，如：Menu::setSubMenus
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*@param<E> 泛型实体对象
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*@return 合成好的树
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*/
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public static <E> List<E> makeTree(List<E> list, Predicate<E> rootCheck, BiFunction<E,E,Boolean> parentCheck, BiConsumer<E,List<E>> setSubChildren){
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return list.stream().filter(rootCheck).peek(x->setSubChildren.accept(x,makeChildren(x,list,parentCheck,setSubChildren))).collect(Collectors.toList());
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}
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/**
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*将树打平成tree
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*@paramtree需要打平的树
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*@paramgetSubChildren设置下级数据方法，如：Menu::getSubMenus,x->x.setSubMenus(null)
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*@paramsetSubChildren将下级数据置空方法，如：x->x.setSubMenus(null)
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*@return打平后的数据
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*@param<E>泛型实体对象
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*/
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public static <E> List<E> flat(List<E> tree, Function<E,List<E>> getSubChildren, Consumer<E> setSubChildren){
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List<E> res = new ArrayList<>();
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forPostOrder(tree,item->{
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setSubChildren.accept(item);
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res.add(item);
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},getSubChildren);
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return res;
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}
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/**
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*前序遍历
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*
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*@paramtree需要遍历的树
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*@paramconsumer遍历后对单个元素的处理方法，如：x->System.out.println(x)、System.out::println打印元素
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*@paramsetSubChildren设置下级数据方法，如：Menu::getSubMenus,x->x.setSubMenus(null)
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*@param<E>泛型实体对象
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*/
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public static <E> void forPreOrder(List<E> tree,Consumer<E> consumer,Function<E,List<E>> setSubChildren){
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for(E l : tree){
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consumer.accept(l);
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List<E> es = setSubChildren.apply(l);
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if(es != null && es.size() > 0){
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forPreOrder(es,consumer,setSubChildren);
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}
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}
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}
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/**
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*层序遍历
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*
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*@paramtree需要遍历的树
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*@paramconsumer遍历后对单个元素的处理方法，如：x->System.out.println(x)、System.out::println打印元素
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*@paramsetSubChildren设置下级数据方法，如：Menu::getSubMenus,x->x.setSubMenus(null)
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*@param<E>泛型实体对象
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*/
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public static <E> void forLevelOrder(List<E> tree,Consumer<E> consumer,Function<E,List<E>> setSubChildren){
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Queue<E> queue=new LinkedList<>(tree);
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while(!queue.isEmpty()){
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E item = queue.poll();
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consumer.accept(item);
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List<E> childList = setSubChildren.apply(item);
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if(childList !=null && !childList.isEmpty()){
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queue.addAll(childList);
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}
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}
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}
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/**
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*后序遍历
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*
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*@paramtree需要遍历的树
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*@paramconsumer遍历后对单个元素的处理方法，如：x->System.out.println(x)、System.out::println打印元素
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*@paramsetSubChildren设置下级数据方法，如：Menu::getSubMenus,x->x.setSubMenus(null)
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*@param<E>泛型实体对象
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*/
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public static <E> void forPostOrder(List<E> tree,Consumer<E> consumer,Function<E,List<E>> setSubChildren){
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for(E item : tree) {
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List<E> childList = setSubChildren.apply(item);
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if(childList != null && !childList.isEmpty()){
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forPostOrder(childList,consumer,setSubChildren);
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}
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consumer.accept(item);
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}
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}
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/**
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*对树所有子节点按comparator排序
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*
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*@paramtree需要排序的树
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*@paramcomparator排序规则Comparator，如：Comparator.comparing(MenuVo::getRank)按Rank正序,(x,y)->y.getRank().compareTo(x.getRank())，按Rank倒序
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*@paramgetChildren获取下级数据方法，如：MenuVo::getSubMenus
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*@return排序好的树
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*@param<E>泛型实体对象
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*/
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public static <E> List<E> sort(List<E> tree, Comparator<? super E> comparator, Function<E,List<E>> getChildren){
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for(E item : tree){
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List<E> childList = getChildren.apply(item);
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if(childList != null &&! childList.isEmpty()){
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sort(childList,comparator,getChildren);
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}
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}
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tree.sort(comparator);
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return tree;
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}
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private static <E> List<E> makeChildren(E parent,List<E> allData,BiFunction<E,E,Boolean> parentCheck,BiConsumer<E,List<E>> children){
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return allData.stream().filter(x->parentCheck.apply(parent,x)).peek(x->children.accept(x,makeChildren(x,allData,parentCheck,children))).collect(Collectors.toList());
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}
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/**
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* 使用样例
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* @param args
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*/
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public static void main(String[] args) {
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MenuVo menu0 = new MenuVo(0L, -1L, "一级菜单", 0);
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MenuVo menu1 = new MenuVo(1L, 0L, "二级菜单", 1);
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MenuVo menu2 = new MenuVo(2L, 0L, "三级菜单", 2);
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MenuVo menu3 = new MenuVo(3L, 1L, "四级菜单", 3);
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MenuVo menu4 = new MenuVo(4L, 1L, "五级菜单", 4);
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MenuVo menu5 = new MenuVo(5L, 2L, "六级菜单", 5);
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MenuVo menu6 = new MenuVo(6L, 2L, "七级菜单", 6);
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MenuVo menu7 = new MenuVo(7L, 3L, "八级菜单", 7);
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MenuVo menu8 = new MenuVo(8L, 3L, "九级菜单", 8);
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MenuVo menu9 = new MenuVo(9L, 4L, "十级菜单", 9);
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//基本数据
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List<MenuVo> menuList = Arrays.asList(menu0,menu1, menu2,menu3,menu4,menu5,menu6,menu7,menu8,menu9);
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//合成树
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/**
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* 第1个参数List list，为我们需要合成树的List，如上面Demo中的menuList
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* 第2个参数Predicate rootCheck，判断为根节点的条件，如上面Demo中pId==-1就是根节点
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* 第3个参数parentCheck 判断为父节点条件，如上面Demo中 id==pId
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* 第4个参数setSubChildren，设置下级数据方法如上面Demo中：Menu::setSubMenus
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*/
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List<MenuVo> tree= TreeUtil.makeTree(menuList, x->x.getPId()==-1L,(x, y)->x.getId().equals(y.getPId()), MenuVo::setSubMenus);
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System.out.println(JSON.toJSONString(tree));
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//先序
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/**
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* 遍历数参数解释:
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* tree 需要遍历的树，就是makeTree()合
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* 成的对象Consumer consumer 遍历后对单个元素的处理方法，如：x-> System.out.println(x)、 postOrder.append(x.getId().toString())
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* Function<E, List> getSubChildren,获取下级数据方法，如Menu::getSubMenus
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*/
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StringBuffer preStr = new StringBuffer();
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TreeUtil.forPreOrder(tree,x-> preStr.append(x.getId().toString()),MenuVo::getSubMenus);
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ObjectUtils.equalsAny("0123456789",preStr.toString());
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//层序
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StringBuffer levelStr=new StringBuffer();
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TreeUtil.forLevelOrder(tree,x-> levelStr.append(x.getId().toString()),MenuVo::getSubMenus);
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ObjectUtils.equalsAny("0123456789",levelStr.toString());
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//后序
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StringBuffer postOrder=new StringBuffer();
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TreeUtil.forPostOrder(tree,x-> postOrder.append(x.getId().toString()),MenuVo::getSubMenus);
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ObjectUtils.equalsAny("7839415620",postOrder.toString());
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// 树平铺
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/**
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* flat()参数解释：
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* tree 需要打平的树,就是makeTree()合成的对象Function<E, List> getSubChildren,
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* 获取下级数据方法，如Menu::getSubMenusConsumer setSubChildren,
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* 设置下级数据方法，如：x->x.setSubMenus(null)
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*/
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List<MenuVo> flat = TreeUtil.flat(tree, MenuVo::getSubMenus,x->x.setSubMenus(null));
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ObjectUtils.equalsAny(flat.size(),menuList.size());
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flat.forEach(x -> {
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if (x.getSubMenus() != null) {
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throw new RuntimeException("树平铺失败");
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}
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});
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// 按rank正序
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/**
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* sort参数解释：
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* tree 需要排序的树,就是makeTree()合成的对象Comparator<? super E> comparator
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* 排序规则Comparator，如：Comparator.comparing(MenuVo::getRank) 按Rank正序 ,(x,y)->y.getRank().compareTo(x.getRank())，按Rank倒序Function<E, List> getChildren
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* 获取下级数据方法，如：MenuVo::getSubMenus
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*/
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List<MenuVo> sortTree= TreeUtil.sort(tree, Comparator.comparing(MenuVo::getRank), MenuVo::getSubMenus);
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// 按rank倒序
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List<MenuVo> sortTreeReverse = TreeUtil.sort(tree, (x,y)->y.getRank().compareTo(x.getRank()), MenuVo::getSubMenus);
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}
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@Data
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static class MenuVo {
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private Long id; // 主键id
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private Long pId; // 父级id
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private String name; // 菜单名称
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private Integer rank = 0; // 排序
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private List<MenuVo> subMenus = new ArrayList<>(); // 子菜单
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public MenuVo(Long id, Long pId, String name, Integer rank) {
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this.id = id;
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this.pId = pId;
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this.name = name;
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this.rank = rank;
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}
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}
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}
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