用 Java 组装树形 List 数据

1. 节点 model 类

package com.huiyou.yzf.tree;
 
import java.util.List;
 
public class TreeNode {

	private String id;  //编号（不一定是主键）
	  
    private String parentId;  //父级编号
  
    private String text;  //显示名称
  
    private String state;//combotree 设置为closed 则默认此节点不展开
  
    private List<TreeNode> children;  
  
    public TreeNode(String id, String text, String parentId) {  
        this.id = id;  
        this.parentId = parentId;  
        this.text = text;  
    }  
    public TreeNode(String id, String text, TreeNode parent) {  
        this.id = id;  
        this.parentId = parent.getId();  
        this.text = text;  
    }
    public TreeNode(String id, String text, String parentId,String state) {  
        this.id = id;  
        this.parentId = parentId;  
        this.text = text;  
        this.state = state;
    } 
  
    public String getParentId() {  
        return parentId;  
    }  
  
	public void setParentId(String parentId) {  
        this.parentId = parentId;  
    }  
  
    public String getText() {  
        return text;  
    }  
  
    public void setText(String text) {  
        this.text = text;  
    }  
  
    public String getId() {  
        return id;  
    }  
  
    public void setId(String id) {  
        this.id = id;  
    }  
  
    public List<TreeNode> getChildren() {  
        return children;  
    }  
  
    public void setChildren(List<TreeNode> children) {  
        this.children = children;  
    }  
  
    public String getState() {
		return state;
	}
	public void setState(String state) {
		this.state = state;
	}
	@Override  
    public String toString() {  
        return "TreeNode{" +  
                "id='" + id + '\'' +  
                ", parentId='" + parentId + '\'' +  
                ", text='" + text + '\'' +
                ", state='" + state + '\''+ 
                ", children=" + children +  
                '}';  
    }
}

2.树形 List 构造器（两种方式：1 循环 2 递归）---配有测试 main 方法

package com.huiyou.yzf.tree;
 
import java.util.ArrayList;
import java.util.List;
 
public class TreeBuider {
 
	/** 
     * 两层循环实现建树 
     * @param treeNodes 传入的树节点列表 
     * @return 
     */  
	public static List<TreeNode> bulid(List<TreeNode> treeNodes) {  
  
        List<TreeNode> trees = new ArrayList<TreeNode>();  
  
        for (TreeNode treeNode : treeNodes) {  
  
            if ("0".equals(treeNode.getParentId())) {  
                trees.add(treeNode);  
            }  
  
            for (TreeNode it : treeNodes) {  
                if (it.getParentId().equals(treeNode.getId())) {  
                    if (treeNode.getChildren() == null) {  
                        treeNode.setChildren(new ArrayList<TreeNode>());  
                    }  
                    treeNode.getChildren().add(it);  
                }  
            }  
        }  
        return trees;  
    }  
  
    /** 
     * 使用递归方法建树 
     * @param treeNodes 
     * @return 
     */  
    public static List<TreeNode> buildByRecursive(List<TreeNode> treeNodes) {  
        List<TreeNode> trees = new ArrayList<TreeNode>();  
        for (TreeNode treeNode : treeNodes) {  
            if ("0".equals(treeNode.getParentId())) {  
                trees.add(findChildren(treeNode,treeNodes));  
            }  
        }  
        return trees;  
    }  
  
    /** 
     * 递归查找子节点 
     * @param treeNodes 
     * @return 
     */  
    public static TreeNode findChildren(TreeNode treeNode,List<TreeNode> treeNodes) {  
        for (TreeNode it : treeNodes) {  
            if(treeNode.getId().equals(it.getParentId())) {  
                if (treeNode.getChildren() == null) {  
                    treeNode.setChildren(new ArrayList<TreeNode>());  
                }  
                treeNode.getChildren().add(findChildren(it,treeNodes));  
            }  
        }  
        return treeNode;  
    }  
  
  
  
    public static void main(String[] args) {  
  
        TreeNode treeNode1 = new TreeNode("1","广州","0");  
        TreeNode treeNode2 = new TreeNode("2","深圳","0");  
  
        TreeNode treeNode3 = new TreeNode("3","天河区",treeNode1);  
        TreeNode treeNode4 = new TreeNode("4","越秀区",treeNode1);  
        TreeNode treeNode5 = new TreeNode("5","黄埔区",treeNode1);  
        TreeNode treeNode6 = new TreeNode("6","石牌",treeNode3);  
        TreeNode treeNode7 = new TreeNode("7","百脑汇",treeNode6);  
  
        TreeNode treeNode8 = new TreeNode("8","南山区",treeNode2);  
        TreeNode treeNode9 = new TreeNode("9","宝安区",treeNode2);  
        TreeNode treeNode10 = new TreeNode("10","科技园",treeNode8);  
  
  
        List<TreeNode> list = new ArrayList<TreeNode>();  
  
        list.add(treeNode1);  
        list.add(treeNode2);  
        list.add(treeNode3);  
        list.add(treeNode4);  
        list.add(treeNode5);  
        list.add(treeNode6);  
        list.add(treeNode7);  
        list.add(treeNode8);  
        list.add(treeNode9);  
        list.add(treeNode10);  
  
        List<TreeNode> trees = bulid(list);  
        System.out.println(trees);
        List<TreeNode> trees_ = buildByRecursive(list);  
        System.out.println(trees_);
  
    }  
}

节点 model 类中属性 可根据实际情况进行改变，当 list 存在多级关系时，常会在 Java 组装成树形 Json 数据返回，将数据与节点 model 对应，用上述构造器 中任一方法都可实现 多级 list 数据组装，然后进行后续处理。

以前借鉴某位博主的，地址已找不到，最近又用到 ，在此记录一下，主要供日后使用。
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版权声明：本文为 CSDN 博主「牛肉炒刀削」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/ZaberyJava/article/details/81914857