package com.ycl.system.domain;
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import org.apache.commons.lang3.ObjectUtils;
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import java.util.ArrayList;
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import java.util.LinkedHashMap;
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import java.util.List;
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import java.util.Map;
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/**
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* 树形结构工具类，如：菜单、部门等
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*
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* @author Mark sunlightcs@gmail.com
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* @since 1.0.0
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*/
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public class TreeUtils {
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/**
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* 根据pid，构建树节点
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*/
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public static <T extends TreeNode> List<T> build(List<T> treeNodes, Long pid) {
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//pid不能为空
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if(ObjectUtils.isEmpty(pid)) {
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return null;
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}
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List<T> treeList = new ArrayList<>();
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for (T treeNode : treeNodes) {
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if (pid.equals(treeNode.getParentId())) {
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treeList.add(findChildren(treeNodes, treeNode));
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}
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}
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return treeList;
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}
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/**
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* 查找子节点
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*/
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private static <T extends TreeNode> T findChildren(List<T> treeNodes, T rootNode) {
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for (T treeNode : treeNodes) {
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if (rootNode.getId().equals(treeNode.getParentId())) {
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rootNode.getChildren().add(findChildren(treeNodes, treeNode));
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}
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}
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return rootNode;
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}
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/**
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* 构建树节点
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*/
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public static <T extends TreeNode> List<T> build(List<T> treeNodes) {
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List<T> result = new ArrayList<>();
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//list转map
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Map<Long, T> nodeMap = new LinkedHashMap<>(treeNodes.size());
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for (T treeNode : treeNodes) {
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nodeMap.put(treeNode.getId(), treeNode);
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}
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for (T node : nodeMap.values()) {
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T parent = nodeMap.get(node.getParentId());
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if (parent != null && !(node.getId().equals(parent.getId()))) {
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parent.getChildren().add(node);
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continue;
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}
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result.add(node);
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}
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return result;
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}
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}
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