1.pom文件引进maven

    <groupId>com.baomidou

    <artifactId>mybatis-plus-annotation

    <version>3.2.0

    <groupId>com.baomidou

    <artifactId>mybatis-plus-extension

    <version>3.2.0

</dependency>

2.实体加注解：实体前与JSONObject字段前

@TableName(autoResultMap = true)

public class W  {

    @TableField(typeHandler = FastjsonTypeHandler.class)

    JSONObject ratingJson;

}

3.xml文件中加配置

<resultMap id="BaseResultMap（下面select引用的resultMap）" type="实体W路径" > 

 <result column="ratingJson（JSONObject字段名）" 

property="ratingJson（JSONObject字段名）" 

jdbcType="OTHER" javaType="com.alibaba.fastjson.JSONObject"  

typeHandler="com.baomidou.mybatisplus.extension.handlers.FastjsonTypeHandler" />

</resultMap>

<select id="getW" resultType="实体W路径" resultMap="BaseResultMap">                

SELECT  r.rating_json_ ratingJson  FROM    `waybill_rating_` r 

</select>