浅谈Mybatis之参数传递的几种姿势

<dependencies>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.2.0</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
</dependencies>

spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/story?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai
    username: root
    password:

CREATE TABLE `money` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(20) NOT NULL DEFAULT '' COMMENT '用户名',
  `money` int(26) NOT NULL DEFAULT '0' COMMENT '钱',
  `is_deleted` tinyint(1) NOT NULL DEFAULT '0',
  `create_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `update_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
  PRIMARY KEY (`id`),
  KEY `name` (`name`)
) ENGINE=InnoDB AUTO_INCREMENT=551 DEFAULT CHARSET=utf8mb4;

@Data
public class MoneyPo {
    private Integer id;

    private String name;

    private Long money;

    private Integer isDeleted;

    private Timestamp createAt;

    private Timestamp updateAt;

    private Integer cnt;
}

@Mapper
public interface MoneyMapper {
}

<?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.git.hui.boot.mybatis.mapper.MoneyMapper">

    <resultMap id="BaseResultMap" type="com.git.hui.boot.mybatis.entity.MoneyPo">
        <id column="id" property="id" jdbcType="INTEGER"/>
        <result column="name" property="name" jdbcType="VARCHAR"/>
        <result column="money" property="money" jdbcType="INTEGER"/>
        <result column="is_deleted" property="isDeleted" jdbcType="TINYINT"/>
        <result column="create_at" property="createAt" jdbcType="TIMESTAMP"/>
        <result column="update_at" property="updateAt" jdbcType="TIMESTAMP"/>
    </resultMap>
    <sql id="money_po">
      id, name, money, is_deleted, create_at, update_at
    </sql>
</mapper>

int addMoney(@Param("id") int id, @Param("money") int money);

<update id="addMoney" parameterType="java.util.Map">
    update money set money=money+#{money} where id=#{id}
</update>

/**
 * 单个参数时，默认可以直接通过参数名来表示，实际上#{}中用任意一个值都可以，没有任何限制，都表示的是这个唯一的参数
 * @param id
 * @return
 */
MoneyPo findById(int id);

/**
 * 演示xml中的 #{} 为一个匹配补上的字符串，也可以正确的实现参数替换
 * @param id
 * @return
 */
MoneyPo findByIdV2(int id);

<select id="findById" parameterType="java.lang.Integer" resultMap="BaseResultMap">
    select
    <include refid="money_po"/>
    from money where id=#{id}
</select>

<select id="findByIdV2" parameterType="java.lang.Integer" resultMap="BaseResultMap">
    select
    <include refid="money_po"/>
    from money where id=#{dd}
</select>

/**
 * 不指定参数名时，mybatis自动封装一个  param1 ... paramN的Map，其中n表示第n个参数
 * 也可以使用 arg0...n 来指代具体的参数
 *
 * @param name
 * @param money
 * @return
 */
List<MoneyPo> findByNameAndMoney(String name, Integer money);

<select id="findByNameAndMoney" resultMap="BaseResultMap">
    select
    <include refid="money_po"/>
    -- from money where name=#{param1} and money=#{param2}
    from money where name=#{arg0} and money=#{arg1}
</select>

/**
 * 参数类型为map时，直接使用key即可
 * @param map
 * @return
 */
List<MoneyPo> findByMap(Map<String, Object> map);

<select id="findByMap" resultMap="BaseResultMap">
    select
    <include refid="money_po"/>
    from money
    <trim prefix="WHERE" prefixOverrides="AND | OR">
        <if test="id != null">
            id = #{id}
        </if>
        <if test="name != null">
            AND name=#{name}
        </if>
        <if test="money != null">
            AND money=#{money}
        </if>
    </trim>
</select>

/**
 * 参数类型为java对象，同样直接使用field name即可
 * @param po
 * @return
 */
List<MoneyPo> findByPo(MoneyPo po);

<select id="findByPo" parameterType="com.git.hui.boot.mybatis.entity.MoneyPo" resultMap="BaseResultMap">
    select
    <include refid="money_po"/>
    from money
    <trim prefix="WHERE" prefixOverrides="AND | OR">
        <if test="id != null">
            id = #{id}
        </if>
        <if test="name != null">
            AND name=#{name}
        </if>
        <if test="money != null">
            AND money=#{money}
        </if>
    </trim>
</select>

List<MoneyPo> findByIdOrCondition(@Param("id") int id, @Param("map") Map<String, Object> map);

List<MoneyPo> findByIdOrConditionV2(int id, Map<String, Object> map);

<select id="findByIdOrCondition" resultMap="BaseResultMap">
    select <include refid="money_po"/> from money where id = #{id} or  `name`=#{map.name}
</select>

<select id="findByIdOrConditionV2" resultMap="BaseResultMap">
    select <include refid="money_po"/> from money where id = #{param1} or `name`=#{param2.name}
</select>