- 主要依赖：mybatis-spring-boot-starter
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.0.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
</dependencies>mybatis.type-aliases-package=com.mybatis.model
spring.datasource.url=jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.DriverSpring Boot 会自动加载 spring.datasource.* 相关配置，数据源就会自动注入到 sqlSessionFactory 中，sqlSessionFactory 会自动注入到 Mapper 中，对了，你一切都不用管了，直接拿起来使用就行了。
在启动类中添加对 mapper 包扫描@MapperScan
@SpringBootApplication
@MapperScan("com.mybatis.mapper")
public class MybatisAnnotationApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisAnnotationApplication.class, args);
}
}或者直接在 Mapper 类上面添加注解@Mapper，建议使用上面那种，不然每个 mapper 加个注解也挺麻烦的
第三步是最关键的一块， Sql 生产都在这里
public interface UserMapper {
@Select("SELECT * FROM users")
@Results({
@Result(property = "userSex", column = "user_sex", javaType = UserSexEnum.class),
@Result(property = "nickName", column = "nick_name")
})
List<UserEntity> getAll();
@Select("SELECT * FROM users WHERE id = #{id}")
@Results({
@Result(property = "userSex", column = "user_sex", javaType = UserSexEnum.class),
@Result(property = "nickName", column = "nick_name")
})
UserEntity getOne(Long id);
@Insert("INSERT INTO users(userName,passWord,user_sex) VALUES(#{userName}, #{passWord}, #{userSex})")
void insert(UserEntity user);
@Update("UPDATE users SET userName=#{userName},nick_name=#{nickName} WHERE id =#{id}")
void update(UserEntity user);
@Delete("DELETE FROM users WHERE id =#{id}")
void delete(Long id);
}为了更接近生产我特地将 user_sex、nick_name 两个属性在数据库加了下划线和实体类属性名不一致，另外 user_sex 使用了枚举
- @Select 是查询类的注解，所有的查询均使用这个
- @Result 修饰返回的结果集，关联实体类属性和数据库字段一一对应，如果实体类属性和数据库属性名保持一致，就不需要这个属性来修饰。
- @Insert 插入数据库使用，直接传入实体类会自动解析属性到对应的值
- @Update 负责修改，也可以直接传入对象
- @Delete 负责删除
注意，使用#符号和$符号的不同：
// This example creates a prepared statement, something like select * from teacher where name = ?;
@Select("Select * from teacher where name = #{name}")
Teacher selectTeachForGivenName(@Param("name") String name);
// This example creates n inlined statement, something like select * from teacher where name = 'someName';
@Select("Select * from teacher where name = '${name}'")
Teacher selectTeachForGivenName(@Param("name") String name);- #{}是预编译处理，$ {}是字符串替换。mybatis在处理#{}时，会将sql中的#{}替换为?号，调用PreparedStatement的set方法来赋值；mybatis在处理 $ { } 时，就是把 ${ } 替换成变量的值。使用 #{} 可以有效的防止SQL注入，提高系统安全性。
@RunWith(SpringRunner.class)
@SpringBootTest
class UserMapperTest {
@Autowired
private UserMapper userMapper;
@Test
public void testInsert() throws Exception {
userMapper.insert(new User("Jax", "123", UserSexEnum.MAN));
userMapper.insert(new User("Luna", "111", UserSexEnum.WOMAN));
userMapper.insert(new User("Amy", "222", UserSexEnum.WOMAN));
Assert.assertEquals(3, userMapper.getAll().size());
}
@Test
public void testQuery() throws Exception {
List<User> users = userMapper.getAll();
System.out.println(users.toString());
}
@Test
public void testUpdate() throws Exception {
User user = userMapper.getOne(1l);
System.out.println(user.toString());
user.setNickName("汤姆");
userMapper.update(user);
Assert.assertTrue(("汤姆".equals(userMapper.getOne(1l).getNickName())));
}
}- Assert.assertEquals();及其重载方法: 1. 如果两者一致, 程序继续往下运行. 2. 如果两者不一致, 中断测试方法, 抛出异常信息 AssertionFailedError .
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