SpringBoot 数据访问

1.引入jdbc开发场景

        
            org.springframework.boot
            spring-boot-starter-data-jdbc
        
        
            mysql
            mysql-connector-java
            5.1.49
        

相当于配置好了JdbcTemplate，HikariDataSource，Tx
2.添加配置项

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/db3
    username: root
    password: root
    driver-class-name: com.mysql.jdbc.Driver

此时就可以使用JdbcTemplate操作数据了

将DruidDataSource注入容器便会替换默认数据源

@Configuration
public class DruidConfiguration {
    @Bean
    @ConfigurationProperties("spring.datasource")// 复用配置文件的数据源配置
    public DataSource dataSource() throws SQLException {
        DruidDataSource druidDataSource = new DruidDataSource();
        return druidDataSource;
    }
}

• 引入mybatis场景启动器

        
            org.mybatis.spring.boot
            mybatis-spring-boot-starter
            2.1.4
        

• 测试场景是否引入成功

1.Mapper接口

@Mapper
public interface UserMapper {

    public List findAll();
    @Select("select count(*) from user")
    public int findTotalCount();
}

2.Mapper.xml

    
        select * from user
    

3.测试方法

@Slf4j
@SpringBootTest
public class MainApplicationTest {

    @Autowired
    private UserMapper userMapper;
    @Test
    public void test4() {
        List users = userMapper.findAll();
        int totalCount = userMapper.findTotalCount();
        log.info("查询结果集：{}", users);
        log.info("总记录数为：{}", totalCount);
    }

mybatis:
# 指定mapper映射文件存放位置
  mapper-locations: classpath:boot/mappers/*.xml
# 开启驼峰命名
  configuration:
    map-underscore-to-camel-case: true