Java 处理省市区数据结构

1、我们先来看看处理后的格式：

一：第一步（创建实体类）：提示：shortname是简称可以忽略

/**
 * 中国 地区表
 * @author ruoyi
 */
@Data
public class TableArea {
    private static final long serialVersionUID = 1L;

    /** ID */
    private Long id;

    /** 父id */
    private Long pid;

    /** 地区名称*/
    private String name;

    /** 子分类 */
    private List<TableArea> children = new ArrayList<TableArea>();
}

二、在通用工具类common创建（Treeselect树结构实体类）

package com.ruoyi.common.core.domain;

import java.io.Serializable;
import java.util.List;
import java.util.stream.Collectors;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.ruoyi.common.core.domain.entity.region.TableArea;

/**
 * Treeselect树结构实体类
 * 
 * @author ruoyi
 */
public class TreeSelect implements Serializable
{
    private static final long serialVersionUID = 1L;

    /** 节点ID */
    private Long id;

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

    /** 子节点 */
    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    private List<TreeSelect> children;

    public TreeSelect()
    {

    }

    public TreeSelect(TableArea tableArea)
    {
        this.id = tableArea.getId();
        this.label = tableArea.getName();
        this.children = tableArea.getChildren().stream().map(TreeSelect::new).collect(Collectors.toList());
    }

    public Long getId()
    {
        return id;
    }

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

    public String getLabel()
    {
        return label;
    }

    public void setLabel(String label)
    {
        this.label = label;
    }

    public List<TreeSelect> getChildren()
    {
        return children;
    }

    public void setChildren(List<TreeSelect> children)
    {
        this.children = children;
    }
}

三、TableAreaMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 将下列SQL语句绑定 dao层对应接口 -->
<mapper namespace="com.ruoyi.enterprise.mapper.TableAreaMapper">

    <resultMap type="TableArea" id="TableAreaResult">
        <result property="id"    column="id"    />
        <result property="pid"    column="pid"    />
        <result property="shortname"    column="shortname"    />
        <result property="name"    column="name"    />
        <result property="mergename"    column="mergename"    />
        <result property="level"    column="level"    />
        <result property="pinyin"    column="pinyin"    />
        <result property="code"    column="code"    />
        <result property="zip"    column="zip"    />
        <result property="first"    column="first"    />
        <result property="lng"    column="lng"    />
        <result property="lat"    column="lat"    />
    </resultMap>

    <sql id="selectTableAreaVo">
        select id, pid, shortname, `name`, mergename, `level`, pinyin, code, zip, `first`, lng, lat from table_area
    </sql>

    <select id="selectTableAreaList" resultMap="TableAreaResult">
        <include refid="selectTableAreaVo"/>   //引入<sql id="selectTableAreaVo"> 里的查询

 </select> </mapper>

四、地区Service接口（忽略mapper接口）

package com.ruoyi.enterprise.service;
import com.ruoyi.common.core.domain.TreeSelect;
import com.ruoyi.common.core.domain.entity.region.TableArea;
import java.util.List;

/**
 * 地区Service接口
 *
 * @author ruoyi
 * @date 2022-05-27
 */
public interface ITableAreaService {

    /**
     * 查询地区列表集合
     * @return
     */
    public List<TableArea> selectTableAreaList();

    /**
     * 构建前端所需要树结构
     *
     * @param tableAreas 地区列表
     * @return 树结构列表
     */
    public List<TableArea> buildTableAreaTree(List<TableArea> tableAreas);

    /**
     * 构建前端所需要下拉树结构
     *
     * @param tableAreas 地区列表
     * @return 下拉树结构列表
     */
    public List<TreeSelect> buildTableAreaTreeSelect(List<TableArea> tableAreas);
}

五、地区Service业务层处理：

package com.ruoyi.enterprise.service.impl;
import com.ruoyi.common.core.domain.TreeSelect;
import com.ruoyi.common.core.domain.entity.region.TableArea;
import com.ruoyi.common.utils.StringUtils;
import com.ruoyi.enterprise.mapper.TableAreaMapper;
import com.ruoyi.enterprise.service.ITableAreaService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;

/**
 * 地区Service业务层处理
 * @author ruoyi
 * @date 2022-05-27
 */
@Service
public class TableAreaServiceImpl implements ITableAreaService {

    private static final Logger log = LoggerFactory.getLogger(TableAreaServiceImpl.class);

    @Autowired
    private TableAreaMapper tableAreaMapper;

    /**
     * 查询地区列表集合
     * @return
     */
    @Override
    public List<TableArea> selectTableAreaList() {
        return tableAreaMapper.selectTableAreaList();
    }

    /**
     * 构建前端所需要树结构
     *
     * @param tableAreas 地区列表
     * @return 树结构列表
     */
    @Override
    public List<TableArea> buildTableAreaTree(List<TableArea> tableAreas) {
        List<TableArea> returnList = new ArrayList<>();
        List<Long> tempList = new ArrayList<>();
        for (TableArea a : tableAreas)
        {
            tempList.add(a.getId());
        }
        for (Iterator<TableArea> iterator = tableAreas.iterator(); iterator.hasNext();)
        {
            TableArea tableArea = (TableArea) iterator.next();
            //如果是顶级节点，遍历该父节点的所有子节点
            if (!tempList.contains(tableArea.getPid())){
                recursionDFn(tableAreas, tableArea);
                returnList.add(tableArea);
            }
        }
        if (returnList.isEmpty())
        {
            returnList = tableAreas;
        }
        return returnList;
    }

    /**
     * 构建前端所需要下拉树结构
     *
     * @param tableAreas 地区列表
     * @return 下拉树结构列表
     */
    @Override
    public List<TreeSelect> buildTableAreaTreeSelect(List<TableArea> tableAreas) {
        List<TableArea> tableAreaTees = buildTableAreaTree(tableAreas);
        return tableAreaTees.stream().map(TreeSelect::new).collect(Collectors.toList());
    }

    /**
     * 递归列表
     * @param list
     * @param t
     */
    private void recursionDFn(List<TableArea> list, TableArea t){
        //得到子节点列表
        List<TableArea> tableAreaList = getChildList(list, t);
        t.setChildren(tableAreaList);
        for(TableArea tChild : tableAreaList){
            if (hasChild(list,tChild)){
                recursionDFn(list, tChild);
            }
        }
    }

    private List<TableArea> getChildList(List<TableArea> list, TableArea t){
        List<TableArea> tList = new ArrayList<>();
        Iterator<TableArea> it = list.iterator();
        while (it.hasNext()){
            TableArea n = (TableArea) it.next();
            if (StringUtils.isNotNull(n.getPid()) && n.getPid().longValue() == t.getId().longValue()){
                tList.add(n);
            }
        }
        return tList;
    }

    private boolean hasChild(List<TableArea> list, TableArea t){
        return getChildList(list, t).size() > 0;
    }
}

六、地区控制层

package com.ruoyi.enterprise.controller;
import com.ruoyi.common.core.controller.BaseController;
import com.ruoyi.common.core.domain.AjaxResult;
import com.ruoyi.common.core.domain.entity.region.TableArea;
import com.ruoyi.enterprise.service.ITableAreaService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;

/**
 * （中国）地区信息控制层
 */
@Api(tags = "中国地区==》接口")
@RestController
@RequestMapping("/tableArea")
public class TableAreaController extends BaseController {

    @Autowired
    private ITableAreaService tableAreaService;

    /**
     * 获取地区下拉树列表
     * @return
     */
    @ApiOperation("地区下拉树接口")
    @GetMapping("/treeSelect")
    public AjaxResult treeSelect(){
        List<TableArea> tableAreas = tableAreaService.selectTableAreaList();
        return AjaxResult.success(tableAreaService.buildTableAreaTreeSelect(tableAreas));
    }

}