Spring初体验-mybatis使用

添加Mybatis依赖mybatis-spring-boot-starter

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.1.1</version>
</dependency>

无xml配置注解版

1.配置数据库连接

在application.properties文件中配置数据库连接

########################################################
###datasource
spring.datasource.url = jdbc:mysql://localhost:3306/how2java
spring.datasource.username = root
spring.datasource.password = mysql
spring.datasource.driverClassName = com.mysql.jdbc.Driver
spring.datasource.max-active=20
spring.datasource.max-idle=8
spring.datasource.min-idle=8
########################################################

2.配置springboot启动时扫描mapper

@SpringBootApplication
@MapperScan("com.example.driving.mapper")
public class DrivingApplication {

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

3.开发mapper

public interface UsersMapper {
    @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(int id);

    @Insert("insert into users(nick_name,password,user_sex) values(#{nickName},#{password},#{userSex})")
    void insert(UserEntity user);

    @Update("update users set nick_name=#{nickName} where id=#{id}")
    void update(UserEntity user);

    @Delete("delete from users where id=#{id}")
    void delete(int id);
}

@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

更多属性点击这里

4.测试使用

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserMapperTest {

    @Resource
    private UsersMapper usersMapper;

    @Test
    public void testInsert() throws Exception {
        usersMapper.insert(new UserEntity(UserSexEnum.男,"a123456","123456"));
        usersMapper.insert(new UserEntity(UserSexEnum.女,"b123456","123456"));
        usersMapper.insert(new UserEntity(UserSexEnum.女,"c123456","123456"));
        Assert.assertEquals(3,usersMapper.getAll().size());
    }

    @Test
    public void testQuery() throws Exception {
        List<UserEntity> users = usersMapper.getAll();
        System.out.println(users.toString());
    }

    @Test
    public void testUpdate() throws Exception {
        UserEntity user = usersMapper.getOne(18);
        System.out.println(user.toString());
        user.nickName = "neo";
        usersMapper.update(user);
        System.out.println(usersMapper.getOne(18).toString());
    }

}

xml配置版

1.配置数据库连接

同上

2.配置application.properties

# mybatis
# 对应实体类的包名
mybatis.typeAliasesPackage=com.example.driving.model
# mapper.xml文件所在位置，我放到了resources下面
mybatis.mapperLocations=classpath:**/mapper/*.xml

3.配置springboot启动时扫描mapper

@SpringBootApplication
@MapperScan("com.example.driving.mapper")
public class DrivingApplication {

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

4.编写Dao层的代码

public interface UserMapper {
    
    List<UserEntity> getAll();
    
    UserEntity getOne(int id);

    void insert(UserEntity user);

    void update(UserEntity user);

    void delete(int id);

}

5.编写Dao接口对应的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.neo.mapper.UserMapper" >
    <resultMap id="BaseResultMap" type="com.neo.entity.UserEntity" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="userName" property="userName" jdbcType="VARCHAR" />
        <result column="passWord" property="passWord" jdbcType="VARCHAR" />
        <result column="user_sex" property="userSex" javaType="com.neo.enums.UserSexEnum"/>
        <result column="nick_name" property="nickName" jdbcType="VARCHAR" />
    </resultMap>
    
    <sql id="Base_Column_List" >
        id, userName, passWord, user_sex, nick_name
    </sql>

    <select id="getAll" resultMap="BaseResultMap"  >
       SELECT 
       <include refid="Base_Column_List" />
       FROM users
    </select>

    <select id="getOne" parameterType="java.lang.Long" resultMap="BaseResultMap" >
        SELECT 
       <include refid="Base_Column_List" />
       FROM users
       WHERE id = #{id}
    </select>

    <insert id="insert" parameterType="com.neo.entity.UserEntity" >
       INSERT INTO 
            users
            (userName,passWord,user_sex) 
        VALUES
            (#{userName}, #{passWord}, #{userSex})
    </insert>
    
    <update id="update" parameterType="com.neo.entity.UserEntity" >
       UPDATE 
            users 
       SET 
        <if test="userName != null">userName = #{userName},</if>
        <if test="passWord != null">passWord = #{passWord},</if>
        nick_name = #{nickName}
       WHERE 
            id = #{id}
    </update>
    
    <delete id="delete" parameterType="java.lang.Long" >
       DELETE FROM
             users 
       WHERE 
             id =#{id}
    </delete>

</mapper>

参考
如何优雅的使用mybatis
mybatis官方文档