springboot2.5.5集成mybatis-plus 3.4.3.4

最新版本的springboot集成mybatis plus(3.4.3.4)

1. 引入pom 

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.3.4</version>
</dependency>

<!-- Mysql驱动包 -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<!-- 增加jdbc的支持 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

2. 新增实体

@Data
@TableName("sys_user")
public class User implements Serializable {

    private String userName;

    private String password;

    @TableId(value = "user_id", type = IdType.AUTO)
    private String userId;

}
3.  新增mapper

@Mapper
public interface UserMapper extends BaseMapper<User> {
    User getUserById(Long id);
}
注意：扫描mapper包既可以在启动类中增加

@MapperScan("com.tcrj.mybatistest.mapper")
也可以在类上直接增加@Mapper 注解，两种方式都可以。

4. 新增service

@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    public User getUserById(Long id) {
        return userMapper.getUserById(1L);
    }

    public User selectById(Long id) {
        return userMapper.selectById(1L);
    }

    public IPage<User> getAll() {
        Page<User> userPage = new Page<>(0, 10);
        return userMapper.selectPage(userPage, null);
    }
}
5. 新增controller

@RestController
@RequestMapping("/api/user")
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/getUserById")
    private User getUserById() {
        return userService.getUserById(1L);
    }

    @GetMapping("/getAll")
    private IPage<User> getAll() {
        return userService.getAll();
    }

}
6. 新增分页

// 最新版
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
    MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
    interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
    return interceptor;
}

7. 遇到的问题
1. org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.tcrj.mybatistest.mapper.UserMapper.selectById
当在实体对象中没有增加主键属性，在调用 selectById的时候就报这个错误，

    2. 分页不起作用

    需要注入mybatis plus 的配置 

   

// 最新版
@Bean
public MybatisPlusInterceptor mybatisPlusInterceptor() {
    MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
    interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
    return interceptor;
}
之前的版本是这样的：

@Bean
public PaginationInnerInterceptor paginationInnerInterceptor() {
    return new PaginationInnerInterceptor();
}
是不起作用的。

8. demo git地址：
https://github.com/jamesbaoyi/mybatisplus-test.git

后续会持续更新。