分页在企业级系统必不可少，特别是早年开发人员，在sql里写limit。后来随着技术不断更新升级，向limit我们无需手写，可以通过插件来实现，插件本质上就是limit(在查询语句后面添加limit来做分页)。
MyBatis有PageHelper做分页，MyBatis-Plus只需添加一个配置(spring)或配置类修改就能实现分页。
一、配置类(关键是分页插件)
package com.blog.tutorial.config;
import com.baomidou.mybatisplus.core.incrementer.IKeyGenerator;
import com.baomidou.mybatisplus.extension.incrementer.H2KeyGenerator;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* @Author: fun
* @Description: 分页拦截器
* @Date: 2020/9/10 10:26
* @Version: 1.0.0
*/@Configuration
public class MybatisPlusConfig {
/**
* 注入主键生成器 */ @Bean
public IKeyGenerator keyGenerator() {
return new H2KeyGenerator();
}
/**
* 分页插件 */ @Bean
public PaginationInterceptor paginationInterceptor() {
return new PaginationInterceptor();
}
}二、编写DAO和XML
package com.blog.tutorial.dao;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.blog.tutorial.entity.Users;
import org.springframework.stereotype.Repository;
import java.util.List;
/**
*
* Mapper 接口 *
* * @author youcong
* @since 2020-04-18
*/@Repository
public interface UsersDao extends BaseMapper {
IPage selectPageVo(Page page);
}
ID AS id, user_login AS userLogin, user_pass AS userPass, user_nicename AS userNicename, user_email AS userEmail, user_url AS userUrl, user_registered AS userRegistered, user_activation_key AS userActivationKey, user_status AS userStatus, display_name AS displayName
三、编写service及其实现类
package com.blog.tutorial.service;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.IService;
import com.blog.tutorial.entity.Users;
/**
* @description:
* @author: youcong
* @time: 2020/11/14 13:26
*/public interface UsersService extends IService {
IPage selectUserPage(Page page);
} package com.blog.tutorial.service.impl;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.blog.tutorial.dao.UsersDao;
import com.blog.tutorial.entity.Users;
import com.blog.tutorial.service.UsersService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
/**
* @description:
* @author: youcong
* @time: 2020/11/14 13:27
*/@Service
public class UsersServiceImpl extends ServiceImpl implements UsersService {
@Autowired
private UsersDao usersDao;
@Override
public IPage selectUserPage(Page page) {
return usersDao.selectPageVo(page);
}
} 四、编写Controller
package com.blog.tutorial.controller;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.blog.tutorial.entity.Users;
import com.blog.tutorial.service.UsersService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @description:
* @author: youcong
* @time: 2020/11/14 13:27
*/@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UsersService usersService;
@GetMapping("/list")
public Map list(@RequestParam Integer pageNum, @RequestParam Integer pageSize) {
Map returnMap = new HashMap<>();
Page page = new Page<>(pageNum, pageSize);
IPage data = usersService.selectUserPage(page);
returnMap.put("count", data.getTotal());
returnMap.put("data", data.getRecords());
return returnMap;
}
} 五、测试
效果图如下:
数据刚好十条，并且有总条数。
六、总结
本次例子用的是自己写的sql并结合MyBatis-Plus分页插件来实现分页的，适用场景比较广，通常是多表关联的查询语句等。如果是单表的话，直接用MyBatis-Plus单表自带的分页API即可。