java树形菜单对象生成

1，TreeNode对象

package com.ruoyi.system.utils.Vo;

import java.util.ArrayList;
import java.util.List;

public class TreeNode {
    
    

  /**
   * 节点ID
   */
  private Integer id;

  /**
   * 节点名称
   */
  private String name;

  /**
   * 父节点ID
   */
  private Integer parentId;

  /**
   * 子节点列表
   */
  private List childrenList = new ArrayList();

  public Integer getId() {
    
    
    return id;
  }

  public void setId(Integer id) {
    
    
    this.id=id;
  }

  public String getName() {
    
    
    return name;
  }

  public void setName(String name) {
    
    
    this.name=name;
  }

  public Integer getParentId() {
    
    
    return parentId;
  }

  public void setParentId(Integer parentId) {
    
    
    this.parentId=parentId;
  }

  public List getChildrenList() {
    
    
    return childrenList;
  }

  public void setChildrenList(List childrenList) {
    
    
    this.childrenList=childrenList;
  }
}

2，TreeUtil

package com.ruoyi.system.utils;

import com.ruoyi.system.utils.Vo.TreeNode;

import java.util.ArrayList;
import java.util.List;

public class TreeUtil {
    
    

  private List<TreeNode> treeNodeList =new ArrayList<>();

  public TreeUtil(List<TreeNode> list){
    
    
    treeNodeList = list;
  }

  /**
   * 获取节点信息
   * @param nodeId 节点ID
   * @return
   */
  public TreeNode getNodeById(int nodeId){
    
    
    TreeNode treeNode = new TreeNode();
    for (TreeNode item : treeNodeList) {
    
    
      if (item.getId() == nodeId) {
    
    
        treeNode = item;
        break;
      }
    }
    return treeNode;
  }

  /**
   * 获取子节点信息
   * @param nodeId 节点ID
   * @return
   */
  public List<TreeNode> getChildrenNodeById(int nodeId){
    
    
    List<TreeNode> childrenTreeNode = new ArrayList<TreeNode>();
    for (TreeNode item : treeNodeList) {
    
    
      if(item.getParentId() == nodeId){
    
    
        childrenTreeNode.add(item);
      }
    }
    return childrenTreeNode;
  }

  /**
   * 递归生成Tree结构数据
   * @param rootId 根节点ID
   * @return
   */
  public TreeNode generateTreeNode(int rootId){
    
    
    TreeNode root = this.getNodeById(rootId);
    List<TreeNode> childrenTreeNode = this.getChildrenNodeById(rootId);
    for (TreeNode item : childrenTreeNode) {
    
    
      TreeNode node = this.generateTreeNode(item.getId());
      root.getChildrenList().add(node);
    }
    return root;
  }

  public static void main(String[] args) {
    
    
    List<TreeNode> nodeList = new ArrayList<>();
    TreeNode treeNode = new TreeNode();
    treeNode.setId(1);
    treeNode.setName("中国");
    treeNode.setParentId(0);
    nodeList.add(treeNode);
    treeNode = new TreeNode();
    treeNode.setId(2);
    treeNode.setName("北京市");
    treeNode.setParentId(1);
    nodeList.add(treeNode);
    treeNode = new TreeNode();
    treeNode.setId(3);
    treeNode.setName("浙江省");
    treeNode.setParentId(1);
    nodeList.add(treeNode);
    treeNode = new TreeNode();
    treeNode.setId(4);
    treeNode.setName("杭州市");
    treeNode.setParentId(3);
    nodeList.add(treeNode);
    treeNode = new TreeNode();
    treeNode.setId(5);
    treeNode.setName("西湖区");
    treeNode.setParentId(4);
    nodeList.add(treeNode);
    treeNode = new TreeNode();
    treeNode.setId(6);
    treeNode.setName("滨江区");
    treeNode.setParentId(4);
    nodeList.add(treeNode);
    treeNode = new TreeNode();
    treeNode.setId(7);
    treeNode.setName("金华市");
    treeNode.setParentId(3);
    nodeList.add(treeNode);
    TreeUtil treeUtil = new TreeUtil(nodeList);
    treeNode = treeUtil.generateTreeNode(1);
    System.out.println("树状结构Json格式数据：" + JsonUtils.objectToJson(treeNode, 1));
  }
}

3，JsonUtil

package com.ruoyi.system.utils;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.List;

public class JsonUtils {
    
    

  // 定义jackson对象
  private static final ObjectMapper MAPPER = new ObjectMapper();

  /**
   * 将对象转换成json字符串
   * @param obj 需转换的对象
   * @param  flag Json格式化标识（0-否，1-是）
   * @return
   */
  public static <T> String objectToJson(T obj, int flag) {
    
    
    if (obj == null) {
    
    
      return null;
    }
    try {
    
    
      String string;
      if (flag == 1) {
    
    
        string = obj instanceof String ? (String) obj : MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(obj);
      } else {
    
    
        string = obj instanceof String ? (String) obj : MAPPER.writeValueAsString(obj);
      }
      return string;
    } catch (JsonProcessingException e) {
    
    
      e.printStackTrace();
    }
    return null;
  }

  /**
   * 将json结果集转化为对象
   *
   * @param jsonData json数据
   * @param beanType 对象中的object类型
   * @return
   */
  public static <T> T jsonToPojo(String jsonData, Class<T> beanType) {
    
    
    try {
    
    
      T t = MAPPER.readValue(jsonData, beanType);
      return t;
    } catch (Exception e) {
    
    
      e.printStackTrace();
    }
    return null;
  }

  /**
   * 将json数据转换成pojo对象list
   * <p>Title: jsonToList</p>
   * <p>Description: </p>
   * @param jsonData
   * @param beanType
   * @return
   */
  public static <T>List<T> jsonToList(String jsonData, Class<T> beanType) {
    
    
    JavaType javaType = MAPPER.getTypeFactory().constructParametricType(List.class, beanType);
    try {
    
    
      List<T> list = MAPPER.readValue(jsonData, javaType);
      return list;
    } catch (Exception e) {
    
    
      e.printStackTrace();
    }

    return null;
  }

  public static void main(String[] args) {
    
    
    System.out.println("测试字符串对象：" + objectToJson("hello world", 1));
  }

}

4,运行结果