Mybatis resultMap用法之系统数据字典实现

实体对象

字典实体

@Data
@Alias("Dict")
public class SysDict {
    // 字典代码
    private String dictCode;
    // 字典名称
    private String dictName;
    // 0系统 9解析
    private Integer dictType;
    // 字典项列表
    private List<SysDictItem> dictItems;
}

字典项实体

@Data
@Alias("DictItem")
public class SysDictItem {
    // 字典子项代码
    private String dictItemCode;
    // 字典子项展示值
    private String dictItemValue;
    // 字典子项详细描述
    private String dictItemDesc;
	// 自定义json字符串属性
    private Map<String, Object> itemAttrs;

    // 将数据库里json字符串转为map对象
    public void setItemAttrs(String itemAttrs) {
        if (!StringUtils.isEmpty(itemAttrs)) {
            // json字符串转map
            this.itemAttrs = MapperUtils.jsonToMap(itemAttrs);
        }
    }
}

 

Mapper文件

<?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" >
<mapper namespace="com.jaemon.app.mapper.SysDictMapper">
	<resultMap id="DictResultMap" type="Dict">
        <result column="dict_code" property="dictCode" jdbcType="VARCHAR" />
        <result column="dict_name" property="dictName" jdbcType="VARCHAR" />
        <collection property="dictItems" ofType="DictItem" select="queryDictById" column="{dictId=id}" />
    </resultMap>
    
    <select id="queryAllDict" resultMap="DictResultMap">
        select sd.id, sd.dict_code, sd.dict_name
        from sys_dict sd
        where sd.dict_status = 1
    </select>

    <select id="queryDictById" resultType="DictItem">
        select sdi.dict_item_code, sdi.dict_item_value, sdi.dict_item_desc, sdi.item_attrs
        from sys_dict_item sdi
        where sdi.item_status = 1 and sdi.dict_id = #{dictId}
    </select>
</mapper>

resultMap标签具体属性含义解释参见： Mybatis resultMap用法之系统菜单实现

输出案例

{
  "code": 0,
  "msg": "成功",
  "result": [
    {
      "dictCode": "houseStructure",
      "dictName": "房屋结构",
      "dictType": null,
      "dictItems": [
        {
          "dictItemCode": "1",
          "dictItemValue": "钢筋混凝土结构",
          "dictItemDesc": "钢筋混凝土结构",
          "itemAttrs": {
            "left": "(",
            "right": ")"
          }
        },
        {
          "dictItemCode": "2",
          "dictItemValue": "砖混结构",
          "dictItemDesc": "砖混结构",
          "itemAttrs": null
        },
        {
          "dictItemCode": "3",
          "dictItemValue": "砖木结构",
          "dictItemDesc": "砖木结构",
          "itemAttrs": null
        },
        {
          "dictItemCode": "4",
          "dictItemValue": "简易结构",
          "dictItemDesc": "简易结构",
          "itemAttrs": null
        }
      ]
    }
  ]
}

 

数据库

表结构

DROP TABLE IF EXISTS `sys_dict`;
CREATE TABLE `sys_dict`  (
  `id` bigint(18) NOT NULL AUTO_INCREMENT COMMENT '字典ID',
  `dict_code` varchar(55) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '字典代码',
  `dict_name` varchar(125) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '字典名称',
  `dict_status` tinyint(4) NOT NULL DEFAULT 0 COMMENT '字典状态\r\n0： 停用\r\n1： 启用',
  `dict_type` tinyint(4) NULL DEFAULT 0 COMMENT '字典类型(0-系统字典 5-公共 9-解析字典)',
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE INDEX `idx`(`dict_code`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 70 CHARACTER SET = utf8 COLLATE = utf8_general_ci COMMENT = '系统-字典表' ROW_FORMAT = Dynamic;

DROP TABLE IF EXISTS `sys_dict_item`;
CREATE TABLE `sys_dict_item`  (
  `id` bigint(18) NOT NULL AUTO_INCREMENT COMMENT '字典子项id',
  `dict_id` bigint(18) NOT NULL COMMENT '字典ID',
  `dict_item_code` varchar(55) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '字典子项代码',
  `dict_item_value` varchar(125) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '字典子项展示值',
  `dict_item_desc` varchar(125) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT '' COMMENT '字典子项描述',
  `item_status` tinyint(1) NOT NULL DEFAULT 0 COMMENT '字典子项状态\r\n0： 停用\r\n1： 启用',
  `item_attrs` varchar(1024) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '自定义json字符串属性',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 283 CHARACTER SET = utf8 COLLATE = utf8_general_ci COMMENT = '系统-字典子项表' ROW_FORMAT = Dynamic;

表数据

INSERT INTO `sys_dict` VALUES (1, 'houseStructure', '房屋结构', 1, 5);

INSERT INTO `sys_dict_item` VALUES (1, 1, '1', '钢筋混凝土结构', '钢筋混凝土结构', 1, '{\"left\": \"(\", \"right\": \")\"}');
INSERT INTO `sys_dict_item` VALUES (2, 1, '2', '砖混结构', '砖混结构', 1, NULL);
INSERT INTO `sys_dict_item` VALUES (3, 1, '3', '砖木结构', '砖木结构', 1, NULL);
INSERT INTO `sys_dict_item` VALUES (4, 1, '4', '简易结构', '简易结构', 1, NULL);

 

Mapper写法2

	<resultMap id="DictResultMap" type="Dict">
        <result column="dict_code" property="dictCode" jdbcType="VARCHAR"/>
        <result column="dict_name" property="dictName" jdbcType="VARCHAR"/>
        <result column="dict_type" property="dictType" jdbcType="TINYINT"/>
        <collection property="dictItems" resultMap="DictItemsMap"/>
    </resultMap>

    <resultMap id="DictItemsMap" type="DictItem">
        <result column="dict_item_code" property="dictItemCode" jdbcType="VARCHAR"/>
        <result column="dict_item_value" property="dictItemValue" jdbcType="VARCHAR"/>
        <result column="dict_item_desc" property="dictItemDesc" jdbcType="VARCHAR"/>
    </resultMap>

    <select id="findDicts" resultMap="DictResultMap">
        SELECT
               dd.dict_code, dd.dict_name, dd.dict_type,
               ddi.dict_item_code, ddi.dict_item_value, ddi.dict_item_desc
        FROM sys_dict dd
        LEFT JOIN sys_dict_item ddi ON dd.id = ddi.dict_id
        WHERE dd.dict_status = 1 AND ddi.item_status = 1
        <if test="dictCode != null">
            AND dd.dict_code IN
            <foreach collection="dictCodes" item="item" index="index" open="(" separator="," close=")">
                #{item}
            </foreach>
        </if>
        ORDER BY dd.id, ddi.id
    </select>

注意： 该方式由于用到一对多左连接， 所以不支持 sys_dict 级别的分页