Spring Boot中使用mybatis方法指南

下文笔者讲述SpringBoot中使用mybatis的方法分享,如下所示

mybatis简介

mybaits是一个半自动化的ORM框架
 她可以将sql脚本的查询结果转换为实体对象
 在进行mybatis的开发时,我们还需编写相应的sql脚本,用于拉取数据
mybatis常用于互联网的开发

SpringBoot中使用mybatis的实现思路

1.引用mybatis-spring-boot-starter
2.配置文件编写相应信息
3.编写Mapper信息
4.编写测试代码

例:

mybatis-spring-boot-starter引入

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

无配置文件注解版

添加相关maven信息

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <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>1.1.1</version>
    </dependency>
     <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>
     <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>

application.properties中添加相关配置

 
mybatis.type-aliases-package=com.java265.entity

spring.datasource.driverClassName = com.mysql.jdbc.Driver
spring.datasource.url = jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8
spring.datasource.username = root
spring.datasource.password = 123456

 
springboot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 

启动类中添加对mapper包扫描@MapperScan
例

@SpringBootApplication
@MapperScan("com.java265.mapper")
public class Application {

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

Mapper开发

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);

}

@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$符号的区别说明
   @Select("Select * from user where name = #{name}")
User selectTeachForGivenName(@Param("name") String name);

// This example creates n inlined statement, something like select * from user where name = 'someName';
@Select("Select * from user where name = '${name}'")
User selectTeachForGivenName(@Param("name") String name);

dao层开发

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

    @Autowired
    private UserMapper UserMapper;

    @Test
    public void testInsert() throws Exception {
        UserMapper.insert(new UserEntity("aa", "a123456", UserSexEnum.MAN));
        UserMapper.insert(new UserEntity("bb", "b123456", UserSexEnum.WOMAN));
        UserMapper.insert(new UserEntity("cc", "b123456", UserSexEnum.WOMAN));

        Assert.assertEquals(3, UserMapper.getAll().size());
    }

    @Test
    public void testQuery() throws Exception {
        List<UserEntity> users = UserMapper.getAll();
        System.out.println(users.toString());
    }
    
    @Test
    public void testUpdate() throws Exception {
        UserEntity user = UserMapper.getOne(3l);
        System.out.println(user.toString());
        user.setNickName("neo");
        UserMapper.update(user);
        Assert.assertTrue(("neo".equals(UserMapper.getOne(3l).getNickName())));
    }
}

Mybatis之xml版本

配置

application.properties新增以下配置

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

mybatis-config.xml配置

<configuration>
    <typeAliases>
        <typeAlias alias="Integer" type="java.lang.Integer" />
        <typeAlias alias="Long" type="java.lang.Long" />
        <typeAlias alias="HashMap" type="java.util.HashMap" />
        <typeAlias alias="LinkedHashMap" type="java.util.LinkedHashMap" />
        <typeAlias alias="ArrayList" type="java.util.ArrayList" />
        <typeAlias alias="LinkedList" type="java.util.LinkedList" />
    </typeAliases>
</configuration>

User映射文件

 
<mapper namespace="com.java265.mapper.UserMapper" >
    <resultMap id="BaseResultMap" type="com.java265.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.java265.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.java265.entity.UserEntity" >
       INSERT INTO 
               users
               (userName,passWord,user_sex) 
           VALUES
               (#{userName}, #{passWord}, #{userSex})
    </insert>
    
    <update id="update" parameterType="com.java265.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>

Dao层代码

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

    void insert(UserEntity user);

    void update(UserEntity user);

    void delete(Long id);

}