mybatis 通过TypeHandler list转换 string类型转换_typehandler list转string-优快云博客

本文链接：https://blog.youkuaiyun.com/lMasterSparkl/article/details/114893128

本文介绍如何在MyBatis中使用自定义TypeHandler实现List类型与String类型的相互转换，包括工具类实现与XML配置示例。

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1.问题描述

因为需要存入list数据类型所以mybatis端需要TypeHandler进行类型转换

2.代码

1.转换工具类

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.springframework.stereotype.Component;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

/**
 * @ClassName ListToStringHandler
 * @Description mybatis list转换为String 相互转换工具类
 * @Author ygt
 * @Date 2021/3/3 14:49
 * @Version V1.0
 */
@Component
public class ListToStringHandler  extends BaseTypeHandler<List> {

    @Override
    public void setNonNullParameter(PreparedStatement preparedStatement, int i, List list, JdbcType jdbcType) throws SQLException {
        preparedStatement.setString(i, JSON.toJSONString(list));
    }

    @Override
    public List getNullableResult(ResultSet resultSet, String s) throws SQLException {
        JSONArray jsonArray = JSONArray.parseArray( resultSet.getString(s));
        return jsonArray;
    }

    @Override
    public List getNullableResult(ResultSet resultSet, int i) throws SQLException {
        JSONArray jsonArray = JSONArray.parseArray( resultSet.getString(i));
        return jsonArray;
    }

    @Override
    public List getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
        JSONArray jsonArray = JSONArray.parseArray( callableStatement.getString(i));
        return jsonArray;
    }
}

2.sql xml 部分代码
需要注意有的地方需要加双引号有的地方不需要加双引号
否则有可能会出现类似如下报错其实是双引号多了
mybatis: No enum constant org.apache.ibatis.type.JdbcType.“VARCHAR”

<resultMap id="BaseResultMap" type="xxxx.GameMatch">
    <id column="id" jdbcType="INTEGER" property="id" />
    <result column="game_id" jdbcType="INTEGER" property="gameId" />
    <result column="positions" jdbcType="VARCHAR"  property="positions" typeHandler="xxx.util.ListToStringHandler" />
    <result column="sub_channels" jdbcType="VARCHAR"  property="subChannels" typeHandler="xxx.util.ListToStringHandler" />
  </resultMap>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
    delete from game_match
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="xxx.model.GameMatch">
    insert into game_match (id, game_id, positions, 
      sub_channels)
    values (#{id,jdbcType=INTEGER}, #{gameId,jdbcType=INTEGER}, #{positions, jdbcType=VARCHAR ,typeHandler=xxx.util.ListToStringHandler},
      #{subChannels,jdbcType=VARCHAR})
  </insert>
  <update id="updateByPrimaryKey" parameterType="xxx.model.GameMatch">
    update game_match
    set game_id = #{gameId,jdbcType=INTEGER},
      positions = #{positions, jdbcType=VARCHAR ,typeHandler=xxx.util.ListToStringHandler},
      sub_channels = #{subChannels, jdbcType=VARCHAR ,typeHandler=xxx.util.ListToStringHandler}
    where id = #{id,jdbcType=INTEGER}
  </update>