Spring boot（2 - 0）整合mybatis

在上一小节，我们学习了快速搭建一个Spring boot项目，在这一部分，我们来学习整合mybatis和阿里巴巴druid

1. 新建springboot项目，spring-boot-mybatis

pom.xml文件中增加mybatis相关配置：

 <!-- mybatis -->
 <dependency>
	<groupId>org.mybatis.spring.boot</groupId>
	<artifactId>mybatis-spring-boot-starter</artifactId>
	<version>1.3.2</version>
</dependency>
		
<!-- mysql -->
<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
</dependency>
	    
<!-- spring jdbc -->
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

2. 新建数据库tests，并且新建表user_info

CREATE TABLE `user_info` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT COMMENT 'id',
  `username` varchar(64) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '用户名',
  `password` varchar(256) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '密码',
  `email` varchar(64) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '邮箱',
  `created` datetime DEFAULT NULL COMMENT '创建时间',
  `updated` datetime DEFAULT NULL COMMENT '更新时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

3. 在application.properties配置文件中增加数据库相关配置

spring.datasource.driverClassName = com.mysql.cj.jdbc.Driver

spring.datasource.url = jdbc:mysql://localhost:3306/tests?useUnicode=true&characterEncoding=utf-8

spring.datasource.username = test

spring.datasource.password = 12345678


mybatis.mapper-locations=classpath:/mapper/**/*.xml

Spring boot会自动扫描spring.datasource开头的相关配置；另外，我的mapper.xml文件放在/src/main/resources/mapper下，所以增加mybatis.mapper-locations的相关配置。

4. 编写数据库对应的实体类 UserInfo.java

public class UserInfo {
    private Long id;

    private String username;

    private String password;

    private String email;

    private Date created;

    private Date updated;

    // 省略setter getter方法
}

5. 编写Mapper接口 UserInfoMapper.java

public interface UserInfoMapper {

    int insert(UserInfo record);

    UserInfo selectByPrimaryKey(Long id);

}

6.  编写UserInfoMapper.xml 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.demo.mapper.UserInfoMapper" >
  <resultMap id="BaseResultMap" type="com.demo.model.UserInfo" >
    <id column="id" property="id" jdbcType="BIGINT" />
    <result column="username" property="username" jdbcType="VARCHAR" />
    <result column="password" property="password" jdbcType="VARCHAR" />
    <result column="email" property="email" jdbcType="VARCHAR" />
    <result column="created" property="created" jdbcType="TIMESTAMP" />
    <result column="updated" property="updated" jdbcType="TIMESTAMP" />
  </resultMap>

  <sql id="Base_Column_List" >
    id, username, password, email, created, updated
  </sql>
 
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Long" >
    select 
    <include refid="Base_Column_List" />
    from user_info
    where id = #{id,jdbcType=BIGINT}
  </select>

  <insert id="insert" parameterType="com.demo.model.UserInfo" useGeneratedKeys="true" keyProperty="id" >
    insert into user_info (username, password, email, 
      created, updated)
    values (#{username,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{email,jdbcType=VARCHAR}, 
      #{created,jdbcType=TIMESTAMP}, #{updated,jdbcType=TIMESTAMP})
  </insert>
 
</mapper>

7. 编写接口类：UserInfoService.java

public interface UserInfoService {

	public void insert(UserInfo usrInfo);
	
	public UserInfo selectById(Long id);
	
}

8. 接口实现类UserInfoServiceImpl.java，这里注意要加上@Service注解，让这个类能让Spring管理。

@Service
public class UserInfoServiceImpl implements UserInfoService {
	
	@Autowired
	private UserInfoMapper userInfoMapper;

	@Override
	public void insert(UserInfo usrInfo) {
		userInfoMapper.insertSelective(usrInfo);
	}

	@Override
	public UserInfo selectById(Long id) {
		return userInfoMapper.selectByPrimaryKey(id);
	}

}

9. 在主程序启动类上加注解@MapperScan("com.demo.mapper")，表明该包下的类是Mapper接口

@SpringBootApplication
@MapperScan("com.demo.mapper")
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}   

}

写到这里，Spring boot整合mybatis就已经完成了，目录结构如下

这个时候，让我们编写测试用例测试一下，测试类UserInfoServiceImplTest.java

public class UserInfoServiceImplTest extends SimpleTest{
	
	@Autowired
	private UserInfoService userInfoService;

	@Test
	public void insert() {
		UserInfo usrInfo = new UserInfo();
		usrInfo.setUsername(UUID.randomUUID().toString());
		usrInfo.setPassword("12345678");
		usrInfo.setEmail("test@gmail.com");
		usrInfo.setCreated(new Date());
		usrInfo.setUpdated(new Date());
		userInfoService.insert(usrInfo);
	}

	@Test
	public void selectById() {
		Long id = 1L;
		userInfoService.selectById(id);
	}
	
}

SimpleTest.java

@RunWith(SpringRunner.class)
@SpringBootTest(classes = Application.class)
public class SimpleTest extends AbstractJUnit4SpringContextTests{

}

分别运行insert()和selectById()，即可看到正确的结果，update和delete操作可以自行尝试操作。

github源码：https://github.com/johnwongz/spring-boot-demo