java list根據id獲取子節點

工做中因業務需求,將數據庫中的樹狀結構的數據根據父節點獲取全部的子節點java

實現思路node

1.獲取整個數據的list集合數據數據庫

2.將數據分組,java8 list有groupby分組,java8以前的本身遍歷整理json

3.分組後遞歸獲取子節點,有子節點的添加,沒有的設置子節點並刪除分組的數據,知道分組數據刪完ide

Tree.javaui

@Data
public class Tree {
    private Integer id;
    private Integer pId;
    private String key;
    private String value;
    private List<Tree> childList;
}

TreeUtils.javaspa

public class TreeUtils { static List<Tree> trees ; static { String jsonStr = "[" +
                "{\"id\":100,\"pId\":1,\"key\":\"root\", \"value\": \"root\"}," +
                "{\"id\":1000,\"pId\":100,\"key\":\"node1\", \"value\": \"node1\"}," +
                "{\"id\":2000,\"pId\":100,\"key\":\"node2\",\"value\": \"node2\"}," +
                "{\"id\":3000,\"pId\":100,\"key\":\"node3\",\"value\": \"node3\"}," +
                "{\"id\":1100,\"pId\":1000,\"key\":\"node11\",\"value\": \"node11\"}," +
                "{\"id\":1200,\"pId\":1000,\"key\":\"node12\",\"value\": \"node12\"}," +
                "{\"id\":1110,\"pId\":1100,\"key\":\"node111\",\"value\": \"node111\"}," +
                "{\"id\":1120,\"pId\":1100,\"key\":\"node112\",\"value\": \"node112\"}," +
                "{\"id\":2100,\"pId\":2000,\"key\":\"node21\",\"value\": \"node21\"}," +
                "{\"id\":2200,\"pId\":2000,\"key\":\"node22\",\"value\": \"node22\"}," +
                "{\"id\":2110,\"pId\":2100,\"key\":\"node211\",\"value\": \"node21\"}" +
                "]"; trees = JSONObject.parseArray(jsonStr, Tree.class); } public static void main(String[] args) { Tree tree = metaTree(trees, 100); /** * Tree@6073f712[id=100,pId=1,key=root,value=root,childList=[ * Tree(id=1000, pId=100, key=node1, value=node1, childList=[ * Tree(id=1100, pId=1000, key=node11, value=node11, childList=[ * Tree(id=1110, pId=1100, key=node111, value=node111, childList=null), * Tree(id=1120, pId=1100, key=node112, value=node112, childList=null)]), * Tree(id=1200, pId=1000, key=node12, value=node12, childList=null)]), * Tree(id=2000, pId=100, key=node2, value=node2, childList=[ * Tree(id=2100, pId=2000, key=node21, value=node21, childList=[ * Tree(id=2110, pId=2100, key=node211, value=node21, childList=null)]), * Tree(id=2200, pId=2000, key=node22, value=node22, childList=null)]), * Tree(id=3000, pId=100, key=node3, value=node3, childList=null)]] */ System.out.println("tree:" + ToStringBuilder.reflectionToString(tree)); } private static Tree metaTree(List<Tree> treeList, Integer id) { //此處getId getPId根據本身實際狀況更改
        Tree treeConfig = treeList.stream().filter(tree -> tree.getId().equals(id)).collect(Collectors.toList()).get(0); Map<Integer, List<Tree>> collect = treeList.stream().filter(type -> type.getPId() != null).collect(Collectors.groupingBy(Tree::getPId)); if (collect != null && collect.size() > 0) { recursion(collect, treeConfig); } return treeConfig; } private static Tree recursion(Map<Integer, List<Tree>> maps, Tree tree) { if (tree.getChildList() == null) { if (maps.get(tree.getId()) != null) { tree.setChildList(maps.get(tree.getId())); maps.remove(tree.getId()); if (maps.size() > 0) { recursion(maps, tree); } } } else { List<Tree> metaTypeList = tree.getChildList(); if (metaTypeList != null && metaTypeList.size() > 0) { for (Tree meta : metaTypeList) { recursion(maps, meta); } } } return tree; } }
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@Data使用的lombok插件,自動生成get set方法插件

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