MyBatis-Plus如何通过注解使用TypeHandler

@Data
@Accessors(chain = true)
@TableName(autoResultMap = true)
public class User {
    private Long id;
    ...
    /**
     * 注意！！ 必须开启映射注解
     *
     * @TableName(autoResultMap = true)
     *
     * 以下两种类型处理器，二选一 也可以同时存在
     *
     * 注意！！选择对应的 JSON 处理器也必须存在对应 JSON 解析依赖包
     */
    @TableField(typeHandler = JacksonTypeHandler.class)
    // @TableField(typeHandler = FastjsonTypeHandler.class)
    private OtherInfo otherInfo;
}

<result column="other_info" jdbcType="VARCHAR" property="otherInfo" typeHandler="com.baomidou.mybatisplus.extension.handlers.JacksonTypeHandler" />

@TableName(autoResultMap = true)
data class Policy  (
    ...
    /**
     * 策略内容，json格式，规则参考文档
     */
    @TableField(typeHandler = PolicyBodyTypeHandler::class)
    var content: PolicyBody? = null,
    ...
)

class PolicyBodyTypeHandler : BaseTypeHandler<PolicyBody>() {
    override fun getNullableResult(p0: ResultSet?, p1: String?): PolicyBody? {
        val result = p0?.getString(p1) ?: return null
        return JSON.parseObject(result, PolicyBody::class.java)
    }
    override fun getNullableResult(p0: ResultSet?, p1: Int): PolicyBody? {
        val result = p0?.getString(p1) ?: return null
        return JSON.parseObject(result, PolicyBody::class.java)
    }
    override fun getNullableResult(p0: CallableStatement?, p1: Int): PolicyBody? {
        val result = p0?.getString(p1) ?: return null
        return JSON.parseObject(result, PolicyBody::class.java)
    }
    override fun setNonNullParameter(statement: PreparedStatement?, index: Int, javaObj: PolicyBody?, jdbcType: JdbcType?) {
        statement?.setString(index, JSON.toJSONString(javaObj))
    }
}

<!-- 通用查询映射结果 -->
    <resultMap id="BaseResultMap" type="com.inooy.write.ucenter.entity.Policy">
        <id column="id" property="id" />
        <result column="code" property="code" />
        <result column="name" property="name" />
        <result column="description" property="description" />
        <result column="content" property="content" typeHandler="com.inooy.write.ucenter.policy.PolicyBodyTypeHandler"/>
        <result column="deleted" property="deleted" />
        <result column="createTime" property="createTime" />
        <result column="updateTime" property="updateTime" />
        <result column="version" property="version" />
    </resultMap>

@Slf4j
@MappedTypes({Object.class})
@MappedJdbcTypes(JdbcType.VARCHAR)
public class WeightListTypeHandler  extends AbstractJsonTypeHandler<Object> {
    private static Gson gson = new Gson();
    private final Class<?> type;
    public WeightListTypeHandler(Class<?> type) {
        if (log.isTraceEnabled()) {
            log.trace("WeightListTypeHandler(" + type + ")");
        }
        Assert.notNull(type, "Type argument cannot be null");
        this.type = type;
    }
    @Override
    protected Object parse(String json) {
        Type type1 = new TypeToken<Map<String, List<WeightItem>>>(){}.getType();
        return gson.fromJson(json, type1);
    }
    @Override
    protected String toJson(Object obj) {
        return gson.toJson(obj);
    }
    public static void setGson(Gson gson) {
        Assert.notNull(gson, "Gson should not be null");
        WeightListTypeHandler.gson = gson;
    }
}

@Data
@NoArgsConstructor
@TableName(value = "mix_target",autoResultMap = true)
public class MixTarget extends Model<MixTarget> {
    @TableId(value = "id", type = IdType.AUTO)
    private Long id;
    /**
     *指标描述
     */
    @TableField("description")
    private String description;
    /**
     * 指标名
     */
    @TableField("name")
    private String name;
    /**
     * 对应属性名
     */
    @TableField("property_name")
    private String propertyName;
    /**
     * 起始点类型
     */
    @TableField("source_type")
    private String sourceType;
    /**
     * 属性对应权值列表
     * key 属性名 value指定条件下的权值
     */
    @TableField(value = "weight_list",typeHandler = WeightListTypeHandler.class,jdbcType = JdbcType.CLOB)
    private Map<String, List<WeightItem>> weightList;
    /**
     * 运行状态
     * 0 新建未运行
     * 1 运行中
     * 2 已运行 成功
     * 3 已运行 失败
     */
    @TableField("status")
    private Integer status;
    /**
     * 是否可用
     * 1 true
     * 0 false
     */
    @TableField("enable")
    private Integer enable;
    @TableField("create_time")
    private LocalDateTime createTime;
}