From c34912ac40c172065e1dd2a861b37076628d7109 Mon Sep 17 00:00:00 2001
From: panwangnan <panwangnan@schbrain.com>
Date: Sat, 29 Jul 2023 00:28:15 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=E9=80=9A=E8=BF=87=E6=A0=91?=
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---
 .../com/schbrain/common/util/TreeUtil.java    | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 commons/common-util/src/main/java/com/schbrain/common/util/TreeUtil.java

diff --git a/commons/common-util/src/main/java/com/schbrain/common/util/TreeUtil.java b/commons/common-util/src/main/java/com/schbrain/common/util/TreeUtil.java
new file mode 100644
index 0000000..411f09f
--- /dev/null
+++ b/commons/common-util/src/main/java/com/schbrain/common/util/TreeUtil.java
@@ -0,0 +1,65 @@
+package com.schbrain.common.util;
+
+import org.apache.commons.collections4.CollectionUtils;
+
+import java.util.*;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+
+/**
+ * 树工具类
+ */
+public class TreeUtil {
+
+    /**
+     * 通过列表构建一个树状结构
+     *
+     * @param nodes 节点列表
+     * @param idGetMethod 获取当前节点ID的方法
+     * @param parentIdGetMethod 获取父节点ID的方法
+     * @param setParentMethod 设置子节点列表的方法
+     * @param parentId 父节点ID，可以为null
+     */
+    public static <T, K> List<T> buildTree(List<T> nodes,
+                                           Function<T, K> idGetMethod,
+                                           Function<T, K> parentIdGetMethod,
+                                           BiConsumer<T, List<T>> setParentMethod,
+                                           K parentId) {
+        if (CollectionUtils.isEmpty(nodes)) {
+            return nodes;
+        }
+        Map<K, List<T>> parentGroupMap = new HashMap<>();
+        for (T node : nodes) {
+            K key = parentIdGetMethod.apply(node);
+            List<T> subNodes = parentGroupMap.getOrDefault(key, new ArrayList<>());
+            subNodes.add(node);
+            parentGroupMap.put(key, subNodes);
+        }
+        return buildTree(idGetMethod, setParentMethod, parentId, parentGroupMap);
+    }
+
+    /**
+     * 递归通过列表构建一个树状结构
+     *
+     * @param idGetMethod 获取当前节点ID的方法
+     * @param setParentMethod 设置子节点列表的方法
+     * @param parentId 父节点ID，可以为null
+     * @param parentGroupMap 存放节点下层节点列表的map
+     */
+    private static <T, K> List<T> buildTree(Function<T, K> idGetMethod,
+                                            BiConsumer<T, List<T>> setParentMethod,
+                                            K parentId, Map<K, List<T>> parentGroupMap) {
+        List<T> nodes = parentGroupMap.get(parentId);
+        if (CollectionUtils.isEmpty(nodes)) {
+            return Collections.emptyList();
+        }
+        nodes.forEach(item -> setParentMethod.accept(item, buildTree(idGetMethod, setParentMethod, idGetMethod.apply(item), parentGroupMap)));
+        return nodes;
+    }
+
+}
+
+
+
+
+
-- 
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