SpringBoot 整合 Mybatis

TIP

SpringBoot 整合 Mybatis 只需要引入起步依赖和简单配置，就可以快速开始使用。

引入依赖

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.3.0</version>
</dependency>
<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
</dependency>

配置数据源

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.example.entity
  configuration:
    map-underscore-to-camel-case: true
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

实体类

@Data
@TableName("user")
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
    private LocalDateTime createTime;
}

Mapper 接口

@Mapper
public interface UserMapper {
    User selectById(Long id);
    List<User> selectAll();
    int insert(User user);
    int update(User user);
    int deleteById(Long id);
}

XML 映射文件

<?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.example.mapper.UserMapper">
    <select id="selectById" resultType="com.example.entity.User">
        SELECT * FROM user WHERE id = #{id}
    </select>

    <select id="selectAll" resultType="com.example.entity.User">
        SELECT * FROM user
    </select>

    <insert id="insert" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO user(name, age, email) VALUES(#{name}, #{age}, #{email})
    </insert>

    <update id="update">
        UPDATE user SET name=#{name}, age=#{age} WHERE id=#{id}
    </update>

    <delete id="deleteById">
        DELETE FROM user WHERE id=#{id}
    </delete>
</mapper>

TIP

整合 Mybatis 后也可以用注解方式写 SQL，但复杂 SQL 建议用 XML 方式更清晰。