使用mybatis-plus如何实现分页查询功能

短命女 2023-09-27 12:35 31阅读 0赞

今天就跟大家聊聊有关使用mybatis-plus如何实现分页查询功能，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。

引入依赖：

<dependency>
       <groupId>com.baomidou</groupId>
       <artifactId>mybatis-plus-boot-starter</artifactId>
       <version>3.2.0</version>
      </dependency>
      
      <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>5.1.27</version>
      </dependency>
      
      <dependency>
       <groupId>com.alibaba</groupId>
       <artifactId>druid</artifactId>
       <version>1.0.29</version>
    　　　　</dependency>

在application.yml配置

spring:
     datasource:
     type: com.alibaba.druid.pool.DruidDataSource
     driver-class-name: com.mysql.jdbc.Driver
     url: jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8
     username: root
     password: 123456

在启动类上面添加@MapperScan注解，扫描mapper包

@SpringBootApplication
    @MapperScan("com.qiao.demo02.mapper")
    public class SpringbootDemo02Application {
    
     public static void main(String[] args) {
      SpringApplication.run(SpringbootDemo02Application.class, args);
     }
    
    }

新建User和UserMapper

![76278cd6d0ad7eeaf98f80f20df21ecb.png][]

user类

@Data
    public class User {
     @TableId
     private Integer userId;
     private String userName;
     private Integer userAge;
     private String userEmail;
    }
    UserMapper接口

public interface UserMapper extends BaseMapper<User> {
     
     }

最重要的是继承BaseMapper接口：里面声明了很强大的CRUD方法

public interface BaseMapper<T> extends Mapper<T> {
     int insert(T entity);
    
     int deleteById(Serializable id);
    
     int deleteByMap(@Param("cm") Map<String, Object> columnMap);
    
     int delete(@Param("ew") Wrapper<T> wrapper);
    
     int deleteBatchIds(@Param("coll") Collection<? extends Serializable> idList);
    
     int updateById(@Param("et") T entity);
    
     int update(@Param("et") T entity, @Param("ew") Wrapper<T> updateWrapper);
    
     T selectById(Serializable id);
    
     List<T> selectBatchIds(@Param("coll") Collection<? extends Serializable> idList);
    
     List<T> selectByMap(@Param("cm") Map<String, Object> columnMap);
    
     T selectOne(@Param("ew") Wrapper<T> queryWrapper);
    
     Integer selectCount(@Param("ew") Wrapper<T> queryWrapper);
    
     List<T> selectList(@Param("ew") Wrapper<T> queryWrapper);
    
     List<Map<String, Object>> selectMaps(@Param("ew") Wrapper<T> queryWrapper);
    
     List<Object> selectObjs(@Param("ew") Wrapper<T> queryWrapper);
    
     IPage<T> selectPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);
    
     IPage<Map<String, Object>> selectMapsPage(IPage<T> page, @Param("ew") Wrapper<T> queryWrapper);
    }

分页查询

这点官方文档讲的也很详细：[https://mp.baomidou.com/guide/page.html][https_mp.baomidou.com_guide_page.html]

新建一个config包，在里面建一个MybatisPlus配置类 返回一个分页拦截器

package com.qiao.demo02.config;
    
    @Configuration
    @ConditionalOnClass(value = {PaginationInterceptor.class})
    public class MybatisPlusConfig {
     @Bean
     public PaginationInterceptor paginationInterceptor() {
      PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
      return paginationInterceptor;
     }
    }

这样就能使用mybatis的分页功能了

Junit测试

@Resource
     private UserMapper userMapper;
     @Test
     public void queryUserForPage(){
      IPage<User> userPage = new Page<>(2, 2);//参数一是当前页，参数二是每页个数
      userPage = userMapper.selectPage(userPage, null);
      List<User> list = userPage.getRecords();
      for(User user : list){
       System.out.println(user);
      }
     }

Controller返回json串

先定义一个包装类UserVo，用来保存分页所需要的数据

package com.qiao.demo02.vo;
    
    @Data
    public class UserVo {
     private Integer current;
     private Integer size;
     private Long total;
     private List<User> userList;
    }

然后在控制器编写代码，这里省略了service层，实际开发业务代码写在service层，Controller只负责：接受参数、调用service层方法处理业务逻辑，返回结果

Controller类贴上了@RestController注解

@GetMapping("queryUser")
     public UserVo queryList(Integer current, Integer size) {
      /**
       * 这些代码应该写在service层
       */
      UserVo userVo = new UserVo();
      IPage<User> page = new Page<>(current, size);
      userMapper.selectPage(page, null);
      userVo.setCurrent(current);
      userVo.setSize(size);
      userVo.setTotal(page.getTotal());
      userVo.setUserList(page.getRecords());
      return userVo;
     }

附上结果，前端直接处理json数据即可

![3438a9cdd91130abda4cbf76dfb93333.png][]

看完上述内容，你们对使用mybatis-plus如何实现分页查询功能有进一步的了解吗？

[76278cd6d0ad7eeaf98f80f20df21ecb.png]: https://img-blog.csdnimg.cn/img_convert/76278cd6d0ad7eeaf98f80f20df21ecb.png
[https_mp.baomidou.com_guide_page.html]: https://mp.baomidou.com/guide/page.html
[3438a9cdd91130abda4cbf76dfb93333.png]: https://img-blog.csdnimg.cn/img_convert/3438a9cdd91130abda4cbf76dfb93333.png