springboot整合通用Mapper入门

springboot整合通用Mapper入门

概述

通用 Mapper 是一个用于简化 MyBatis 操作的开发框架。它通过提供通用的 CRUD（创建、读取、更新、删除）方法，减少了开发者需要编写的重复代码。通用 Mapper 的一个著名的实现是 MyBatis Generator（MyBatis 代码生成器）。

查看这个接口的源码 他继承了很多接口 这些接口就已经帮助我们实现了增删改查

@RegisterMapper
public interface Mapper<T> extends BaseMapper<T>, ExampleMapper<T>, RowBoundsMapper<T>, Marker {
}

@RegisterMapper
public interface BaseMapper<T> extends BaseSelectMapper<T>, BaseInsertMapper<T>, BaseUpdateMapper<T>, BaseDeleteMapper<T> {
}

@RegisterMapper  这是查 可以看到继承了很多
public interface BaseSelectMapper<T> extends SelectOneMapper<T>, SelectMapper<T>, SelectAllMapper<T>, SelectCountMapper<T>, SelectByPrimaryKeyMapper<T>, ExistsWithPrimaryKeyMapper<T> {
}

第一步导入依赖

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.18</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.28</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-jdbc -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
            <version>3.0.6</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>3.0.2</version>
        </dependency>

        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.1.5</version>
        </dependency>
    </dependencies>

第二步配置数据源和mybaits

server:
  port: 80
logging:
  level:
    com.example.springbootdemo1: debug
    org.springframework: info
spring:
  datasource:
     url: jdbc:mysql://localhost:3306/db2
     username: 1111
     password: a118
     driver-class-name: com.mysql.jdbc.Driver
mybatis:
  type-aliases-package: com.example.springbootdemo1
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

第三步 编写一个实体类

@Data
@Table(name = "user")
//根据数据库表自动映射
public class user {
    @Id
    //主键回填  主键一般都是自增的 当自增的时候自动回填到id上面
//    @KeySql(useGeneratedKeys = true)

    private String sno;
    @Column
    //如果符合驼峰规则 user_name --> userName 并且实体类变量和数据库变量一致可以不用这个注解
    private String name;
    private int point ;
}

第四步 编写mapper接口继承通用mapper

import tk.mybatis.mapper.common.Mapper;

public interface userMapper extends Mapper<user> {
}

第五步 在springboot启动类那里加注解通用mapper扫描

@SpringBootApplication
@MapperScan("com.example.springbootdemo1.mapper")
public class Springbootdemo1Application {

    public static void main(String[] args) {

        SpringApplication.run(Springbootdemo1Application.class, args);
    }

}

第六步 编写服务类

@Service
public class userService {

    @Autowired
    private userMapper userMapper1;
    @Transactional
    public user queryById(String id)
    {
        return userMapper1.selectByPrimaryKey(id);根据主键查询
    }
}

第七步 测试

    @Autowired
    private userService userService;

@RequestMapping("/hello/{id}")
    public user hello1 (@PathVariable String id)
    {

        return userService.queryById(id);
    }
}