springboot：如何优雅的使用mybatis

在Spring Boot中优雅使用MyBatis主要包括以下步骤：

1. 添加依赖：在pom.xml中添加Spring Boot Starter MyBatis和数据库驱动的依赖。

<dependencies>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.1.4</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>
    <!-- 数据库驱动依赖，以MySQL为例 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
</dependencies>

2. 配置数据库信息：在application.properties或application.yml中配置数据库信息。

spring.datasource.url=jdbc:mysql://localhost:3306/your_database?useSSL=false&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=yourpassword
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

3. 创建Mapper接口：定义操作数据库的接口，并使用@Mapper注解标记。

package com.example.mapper;
 
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
 
@Mapper
public interface UserMapper {
    @Select("SELECT * FROM users WHERE id = #{id}")
    User findById(int id);
}

4. 使用Mapper：在Service层注入Mapper接口，并使用其方法。

package com.example.service;
 
import com.example.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
@Service
public class UserService {
    private final UserMapper userMapper;
 
    @Autowired
    public UserService(UserMapper userMapper) {
        this.userMapper = userMapper;
    }
 
    public User getUserById(int id) {
        return userMapper.findById(id);
    }
}

5. 配置MyBatis：可以在application.properties或application.yml中配置MyBatis全局设置。

mybatis.type-aliases-package=com.example.model
mybatis.mapper-locations=classpath:mapper/*.xml

6. 优雅的Mapper XML：在src/main/resources/mapper目录下创建对应的XML文件，用于编写复杂的SQL语句。

<?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="findById" resultType="User">
        SELECT * FROM users WHERE id = #{id}
    </select>
</mapper>

以上步骤展示了如何在Spring Boot项