一、关于Mybatis
MyBatis 是一款优秀的持久层框架，它支持自定义 SQL、存储过程以及高级映射。MyBatis 免除了几乎所有的 JDBC 代码以及设置参数和获取结果集的工作。MyBatis 可以通过简单的 XML 或注解来配置和映射原始类型、接口和 Java POJO（Plain Old Java Objects，普通老式 Java 对象）为数据库中的记录。
二、简单使用
1、添加依赖
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.3</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
2、配置
修改application.yml文件，配置数据源以及mapper.xml位置
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC
username: root
password: 123456
mybatis:
type-aliases-package: xyz.lazyrabbit.entity
mapper-locations: classpath:mapper/*.xml
在启动类加入MapperScan注解，配置mapper.java文件位置
@SpringBootApplication
@MapperScan("xyz.lazyrabbit.mapper")
public class MybatisApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisApplication.class, args);
}
}
3、使用注解方式
- 实体类
@Data
public class AccountInfo {
private Integer id;
private String username;
private String email;
private String password;
private String memo;
}
- mapper.java
@Repository
public interface AccountInfoMapper {
@Options(useGeneratedKeys = true, keyProperty = "id")
@SelectKey(statement = "select last_insert_id()", keyProperty = "id", before = false, resultType = Integer.class)
@Insert("insert into t_account_info(username,email,password,memo) values (#{username},#{email},#{password},#{memo})")
void insert(AccountInfo accountInfo);
@Select("select username,email,password,memo from t_account_info where id = #{id}")
AccountInfo findById(Integer id);
@Results({
@Result(property = "id", column = "id"),
@Result(property = "username", column = "u"),
@Result(property = "email", column = "e"),
@Result(property = "password", column = "p"),
@Result(property = "memo", column = "m")
})
@Select("select id id,username u ,email e ,password p ,memo m from t_account_info where username like concat('%',#{name},'%')")
List<AccountInfo> findByName(String name);
@Select("select * from t_account_info")
List<AccountInfo> findAll();
@Update("update t_account_info set username=#{username},email=#{email},password=#{password},memo=#{memo} where id=#{id}")
Integer updateById(AccountInfo accountInfo);
@Delete("delete from t_account_info where id=#{id}")
Integer deleteById(Integer id);
}
4、使用xml方式
- 实体类
@Data
public class AccountInfoType {
private Integer id;
private String accountType;
private String memo;
}
- AccountInfoTypeMapper.java
@Repository
public interface AccountInfoTypeMapper {
List<AccountInfoType> findAll();
Integer insert(AccountInfoType accountInfoType);
Integer updateById(AccountInfoType accountInfoType);
Integer deleteById(Integer id);
}
- AccountInfoTypeMapper.xml
<mapper namespace="xyz.lazyrabbit.mapper.AccountInfoTypeMapper">
<!-- 通用查询映射结果 -->
<resultMap id="BaseResultMap" type="xyz.lazyrabbit.entity.AccountInfoType">
<id column="id" property="id"/>
<result column="account_type" property="accountType"/>
<result column="memo" property="memo"/>
</resultMap>
<!-- 通用查询结果列 -->
<sql id="Base_Column_List">
id, account_type, memo
</sql>
<select id="findAll" resultType="xyz.lazyrabbit.entity.AccountInfoType">
select <include refid="Base_Column_List"/> from t_account_info_type;
</select>
<insert id="insert" parameterType="xyz.lazyrabbit.entity.AccountInfoType">
insert into t_account_info_type (account_type, memo) values (#{accountType},#{memo});
</insert>
<update id="updateById" parameterType="xyz.lazyrabbit.entity.AccountInfoType">
update t_account_info_type set account_type=#{accountType},memo=#{memo} where id=#{id}
</update>
<delete id="deleteById">
delete from t_account_info_type where id=#{id}
</delete>
</mapper>
5、测试
@SpringBootTest
@Slf4j
class MybatisApplicationTests {
@Autowired
AccountInfoMapper accountInfoMapper;
@Autowired
AccountInfoTypeMapper accountInfoTypeMapper;
@Test
void testAnnotation() {
log.info("插入2条数据到数据库");
AccountInfo accountInfo = new AccountInfo();
accountInfo.setUsername("巴黎圣日尔曼");
accountInfo.setEmail("admin@lazyrabbit.xyz");
accountInfo.setPassword("123456");
accountInfo.setMemo("手机");
accountInfoMapper.insert(accountInfo);
AccountInfo accountInfo2 = new AccountInfo();
accountInfo2.setUsername("拜仁慕尼黑");
accountInfo2.setEmail("admin@lazyrabbit.xyz");
accountInfo2.setPassword("123456");
accountInfo2.setMemo("手机");
accountInfoMapper.insert(accountInfo2);
log.info("当前数据库一共有数据：{}条", accountInfoMapper.findAll().size());
Integer id = accountInfo.getId();
AccountInfo findById = accountInfoMapper.findById(id);
log.info("根据ID{}查询数据：{}", id, findById);
AccountInfo findByName = accountInfoMapper.findByName("拜仁慕尼黑").get(0);
log.info("根据Name查询数据：{}", accountInfoMapper.findByName("拜仁慕尼黑"));
findByName.setMemo("今天赌五毛辣条拜仁大胜！！！");
accountInfoMapper.updateById(findByName);
log.info("更新 {} 的备注", findByName.getUsername());
accountInfoMapper.deleteById(findByName.getId());
log.info("删除数据： {} ", findByName.getUsername());
log.info("当前数据库一共有数据：{}条", accountInfoMapper.findAll().size());
}
@Test
void testXml() {
AccountInfoType accountInfoType = new AccountInfoType();
accountInfoType.setAccountType("视频软件");
log.info("录入一条数据");
accountInfoTypeMapper.insert(accountInfoType);
log.info("查询所有数据：{}", accountInfoTypeMapper.findAll());
}
}