treeutil工具类

原文链接

/*** @Description: 树操作方法工具类* @Author: 公众号：赵侠客* @Copyright: Copyright (c) 赵侠客* @Date: 2024-07-22 10:42* @Version: 1.0*/
public class TreeUtil {/*** 将list合成树** @param list 需要合成树的List* @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* @param parentCheck 判断E中为父节点条件，如：(x,y)->x.getId().equals(y.getPId())* @param setSubChildren   E中设置下级数据方法，如： Menu::setSubMenus* @param <E>  泛型实体对象* @return   合成好的树*/public static <E> List<E> makeTree(List<E> list, Predicate<E> rootCheck, BiFunction<E, E, Boolean> parentCheck, BiConsumer<E, List<E>> setSubChildren) {return list.stream().filter(rootCheck).peek(x -> setSubChildren.accept(x, makeChildren(x, list, parentCheck, setSubChildren))).collect(Collectors.toList());}/***  将树打平成tree* @param tree  需要打平的树* @param getSubChildren  设置下级数据方法，如： Menu::getSubMenus,x->x.setSubMenus(null)* @param setSubChildren 将下级数据置空方法，如： x->x.setSubMenus(null)* @return  打平后的数据* @param <E> 泛型实体对象*/public static <E> List<E> flat(List<E> tree, Function<E, List<E>> getSubChildren, Consumer<E> setSubChildren) {List<E> res = new ArrayList<>();forPostOrder(tree, item -> {setSubChildren.accept(item);res.add(item);}, getSubChildren);return res;}/*** 前序遍历** @param tree 需要遍历的树* @param consumer  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* @param setSubChildren  设置下级数据方法，如： Menu::getSubMenus,x->x.setSubMenus(null)* @param <E> 泛型实体对象*/public static <E> void forPreOrder(List<E> tree, Consumer<E> consumer, Function<E, List<E>> setSubChildren) {for (E l : tree) {consumer.accept(l);List<E> es = setSubChildren.apply(l);if (es != null && es.size() > 0) {forPreOrder(es, consumer, setSubChildren);}}}/*** 层序遍历** @param tree 需要遍历的树* @param consumer 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* @param setSubChildren 设置下级数据方法，如： Menu::getSubMenus,x->x.setSubMenus(null)* @param <E> 泛型实体对象*/public static <E> void forLevelOrder(List<E> tree, Consumer<E> consumer, Function<E, List<E>> setSubChildren) {Queue<E> queue = new LinkedList<>(tree);while (!queue.isEmpty()) {E item = queue.poll();consumer.accept(item);List<E> childList = setSubChildren.apply(item);if (childList != null && !childList.isEmpty()) {queue.addAll(childList);}}}/*** 后序遍历** @param tree 需要遍历的树* @param consumer 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* @param setSubChildren 设置下级数据方法，如： Menu::getSubMenus,x->x.setSubMenus(null)* @param <E> 泛型实体对象*/public static <E> void forPostOrder(List<E> tree, Consumer<E> consumer, Function<E, List<E>> setSubChildren) {for (E item : tree) {List<E> childList = setSubChildren.apply(item);if (childList != null && !childList.isEmpty()) {forPostOrder(childList, consumer, setSubChildren);}consumer.accept(item);}}/*** 对树所有子节点按comparator排序** @param tree 需要排序的树* @param comparator  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* @param getChildren 获取下级数据方法，如：MenuVo::getSubMenus* @return 排序好的树* @param <E> 泛型实体对象*/public static <E> List<E> sort(List<E> tree, Comparator<? super E> comparator, Function<E, List<E>> getChildren) {for (E item : tree) {List<E> childList = getChildren.apply(item);if (childList != null && !childList.isEmpty()) {sort(childList,comparator,getChildren);}}tree.sort(comparator);return tree;}private static <E> List<E> makeChildren(E parent, List<E> allData, BiFunction<E, E, Boolean> parentCheck, BiConsumer<E, List<E>> children) {return allData.stream().filter(x -> parentCheck.apply(parent, x)).peek(x -> children.accept(x, makeChildren(x, allData, parentCheck, children))).collect(Collectors.toList());}
}