mybatis中BaseTypeHandler的使用

mybatis中BaseTypeHandler的使用

自定义TypeHandler

package com.cdn.demo.handler;

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;

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

/**
 * @author 蔡定努
 * @date 2023/11/04 16:51
 */
public class StringTypeHandler<T> extends BaseTypeHandler<T> {


    @Override
    public void setNonNullParameter(PreparedStatement preparedStatement, int i, T integer, JdbcType jdbcType) throws SQLException {
        preparedStatement.setObject(i, integer);
    }

    @Override
    public T getNullableResult(ResultSet resultSet, String s) throws SQLException {
        System.out.println(resultSet.getObject(s));
        return (T) resultSet.getObject(s);
    }

    @Override
    public T getNullableResult(ResultSet resultSet, int i) throws SQLException {
        return (T) resultSet.getObject(i);
    }

    @Override
    public T getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
        return (T) callableStatement.getObject(i);
    }
}

实体类

package com.cdn.demo.entity;

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import java.io.Serializable;

import com.cdn.demo.handler.StringTypeHandler;
import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.experimental.Accessors;

/**
 * @author author
 * @since 2023-10-25
 */
@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
@TableName(value = "person",autoResultMap = true)
public class Person implements Serializable {

    private static final long serialVersionUID = 1L;

    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;

    private Integer userId;

    @TableField(typeHandler = StringTypeHandler.class)
    private String job;

    private Integer age;


}

Mapper

package com.cdn.demo.mapper;

import com.cdn.demo.entity.Person;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.cdn.demo.handler.StringTypeHandler;
import org.apache.ibatis.annotations.*;

import java.math.BigDecimal;
import java.util.List;

/**
 * <p>
 *  Mapper 接口
 * </p>
 *
 * @author author
 * @since 2023-10-25
 */
public interface PersonMapper extends BaseMapper<Person> {


    @Select("select * from person where id = 1")
    @Results({
            @Result(property = "job", column = "job", javaType = BigDecimal.class, typeHandler = StringTypeHandler.class)
    })
    List<Person> person();



    List<Person> anno();




}

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">
<mapper namespace="com.cdn.demo.mapper.PersonMapper">

    <!-- 通用查询映射结果 -->
    <resultMap id="BaseResultMap" type="com.cdn.demo.entity.Person">
        <id column="id" property="id" />
        <result column="user_id" property="userId" />
        <result column="job" property="job" typeHandler="com.cdn.demo.handler.StringTypeHandler"/>
        <result column="age" property="age" />
    </resultMap>

    <!-- 通用查询结果列 -->
    <sql id="Base_Column_List">
        id, user_id, job, age
    </sql>

    <select id="anno" resultMap="BaseResultMap">
        select <include refid="Base_Column_List"/> from person where id =1
    </select>

</mapper>

Controller

package com.cdn.demo.controller;


import cn.hutool.core.util.RandomUtil;
import com.cdn.demo.entity.Person;
import com.cdn.demo.mapper.PersonMapper;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

/**
 * <p>
 *  前端控制器
 * </p>
 *
 * @author author
 * @since 2023-10-25
 */
@RestController
@RequestMapping("/person")
public class PersonController {

    @Resource
    private PersonMapper personMapper;


    /**
     * xml方式
     * @author 蔡定努
     */
    @GetMapping("add")
    public void add() {
        Person person1 = new Person();
        person1.setUserId(0);
        person1.setJob(RandomUtil.randomString(3));
        person1.setAge(0);
        personMapper.insert(person1);
    }

    /**
     * xml的方式
     * @author 蔡定努
     */
    @GetMapping("xml")
    public Object xml() {
        return personMapper.person();
    }


    /**
     * 注解的方式
     * @return
     */
    @GetMapping("anno")
    public Object anno() {
        return personMapper.anno();
    }


    /**
     * plus的方式
     * @return
     */
    @GetMapping("plus")
    public Object plus() {
        return personMapper.selectById(1);
    }



}