MyBatisplus分页插件

• • • • • 一、后台分页配置
        • • 1. 配置分页插件
          • 2. 编写分页代码
          • 3. 测试
        • 二、自定义查询
        • • 2.1. 自定义接口
          • 2.2. 自定义查询
          • 2.3. 测试自定义分页

MyBatis Plus自带分页插件（即BaseMapper接口中的selectPage()方法），只要简单的配置即可实现分页功能，具体步骤如下：

新创一个配置类，在配置类里面配置分页插件

package com.gblfy.flowable.config;

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;


@Configuration
public class MyBatisPlusPaginationInnerConfig {

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

}

分页的所有数据都在userPage对象中封装着，所以可以调用userPage对象的一系列方法对分页数据进行操作。

  package com.gblfy.flowable.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.gblfy.flowable.entity.SysUser;
import com.gblfy.flowable.mapper.SysUserMapper;
import com.gblfy.flowable.service.SysUserService;
import com.gblfy.flowable.tools.pager.PagerModel;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;


@Slf4j
@Service
public class SysUserServiceImpl implements SysUserService {

    @Autowired
    private SysUserMapper userMapper;

    @Override
    public PagerModel list(Page page, QueryWrapper queryWrapper) {
        Page userIPage = userMapper.selectPage(page, queryWrapper);
        // 分页的所有数据都在userPage对象中封装着
        // 获取总页数
        long pages = userIPage.getPages();
        //一页显示几条数据
        long size = userIPage.getSize();
        // 获取当前页
        long current = userIPage.getCurrent();
        // 获取当前页数据集合
        List records = userIPage.getRecords();
        // 获取总记录数
        long total = userIPage.getTotal();
        // 当前页是否有下一页
        boolean hasNext = userIPage.hasNext();
        // 当前页是否有上一页
        boolean hasPrevious = userIPage.hasPrevious();

        System.out.println("总页数pages=" + pages);
        System.out.println("当前页current=" + current);
        System.out.println("当前页显示几条数据size=" + size);
        System.out.println("当前页数据集合records=" + records);
        System.out.println("总记录数total=" + total);
        System.out.println("是否有下一页hasNext=" + hasNext);
        System.out.println("是否有上一页hasPrevious=" + hasPrevious);
        return new PagerModel<>(userIPage.getTotal(), records);
    }

    @Override
    public Page listPage(Page page, QueryWrapper queryWrapper) {
        return userMapper.selectPage(page, queryWrapper);
    }
}

当前数据库的user表中有14条记录，设置当前页数为1，每页记录数为10。
如图：

controller

package com.gblfy.flowable.controller;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.gblfy.flowable.entity.SysUser;
import com.gblfy.flowable.service.SysUserService;
import com.gblfy.flowable.tools.pager.PagerModel;
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;


@RestController
@RequestMapping("/page")
public class MyBatisPlusPaginateController {

    @Autowired
    private SysUserService userService;


    @GetMapping("/list")
    public PagerModel list(@RequestParam(value = "keyword", defaultValue = "") String keyword,
                                    @RequestParam(value = "pageNum", defaultValue = "1") Integer pageNum,
                                    @RequestParam(value = "pageSize", defaultValue = "5") Integer pageSize) {

        QueryWrapper queryWrapper = new QueryWrapper<>();//条件构造器
        queryWrapper.like("user_name", keyword);//模糊查询Like
        Page page = new Page(pageNum, pageSize);//分页插件
        return userService.list(page, queryWrapper);//查询数据
    }

    @GetMapping("/listPage")
    public Page listPage(@RequestParam(value = "keyword", defaultValue = "") String keyword,
                                  @RequestParam(value = "pageNum", defaultValue = "1") Integer pageNum,
                                  @RequestParam(value = "pageSize", defaultValue = "5") Integer pageSize) {

        QueryWrapper queryWrapper = new QueryWrapper<>();//条件构造器
        queryWrapper.like("user_name", keyword);//模糊查询Like
        Page page = new Page(pageNum, pageSize);//分页插件
        return userService.listPage(page, queryWrapper);//查询数据
    }
}

默认返回Page基本可以满足，如果自定义返回封装，参考以下案例即可

package com.gblfy.flowable.tools.pager;

import lombok.Builder;
import lombok.Data;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;


@Data
@Builder(toBuilder = true)
public class PagerModel implements Serializable {
    private static final long serialVersionUID = 4804053559968742915L;
    
    private long total;
    
    private List rows = new ArrayList();
    
    private long pages;
    
    private long current;
    
    private long size;
    
    private boolean hasNext;
    
    private boolean hasPrevious;

    public PagerModel() {
    }

    public PagerModel(long total, List rows) {
        this.total = total;
        this.rows = rows;
    }

    public PagerModel(long total, List rows, long pages, long current) {
        this.total = total;
        this.rows = rows;
        this.pages = pages;
        this.current = current;
    }

    public PagerModel(long total, List rows, long pages, long current, long size) {
        this.total = total;
        this.rows = rows;
        this.pages = pages;
        this.current = current;
        this.size = size;
    }

    public PagerModel(long total, List rows, long pages, long current, boolean hasNext, boolean hasPrevious) {
        this.total = total;
        this.rows = rows;
        this.pages = pages;
        this.current = current;
        this.hasNext = hasNext;
        this.hasPrevious = hasPrevious;
    }

    public PagerModel(long total, List rows, long pages, long current, long size, boolean hasNext, boolean hasPrevious) {
        this.total = total;
        this.rows = rows;
        this.pages = pages;
        this.current = current;
        this.size = size;
        this.hasNext = hasNext;
        this.hasPrevious = hasPrevious;
    }
}

如果想自定义查询那么在UserMapper.java里面写个方法

 Page selectPageVo(@Param("page") Page page,@Param("age") Integer age);

UserMapper.xml文件的查询语句

        SELECT id,name,age,email FROM user WHERe age>#{age}

@Test
    void test02(){
        //测试自定义分页
        Page page=new Page<>(1,3);
        userMapper.selectPageVo(page,20);//调用自定义的查询
        System.out.println(page.getRecords());//获取当前页数据 3条记录
        System.out.println(page.getSize());//获取每页的条数 3
        System.out.println(page.getCurrent()); //获取当前页码 1
        System.out.println(page.getPages());//获取总页数 2
        System.out.println(page.getTotal());//获取总记录数 4
        System.out.println(page.hasNext());//获取有没有下一页 true
        System.out.println(page.hasPrevious());//获取是否有上一页 false
    }