Cara menggunakan PageHelper dalam rangka kerja springboot+mybatis

1. Idea

Letakkan semua kandungan yang diperlukan untuk paging ke dalam kelas entiti

Kelas entiti yang diperlukan untuk data paging! Mengandungi nombor halaman, saiz halaman, jumlah item, jumlah halaman, baris permulaan

pagehelpr menyediakan pageInfo kelas ini, kita tidak perlu menciptanya sendiri

2. Logik utama

pilih * dari baris permulaan had nama jadual, paparkan beberapa keping data

#Halaman n memaparkan lima keping data pada setiap halaman

pilih * dari had nama jadual ( n-1)*5,5

#Berapa banyak item yang dipaparkan pada setiap halaman Saiz halaman

3

#Berapa banyak item yang terdapat secara keseluruhan

jumlah

pilih kiraan(*) daripada nama jadual

#Jumlah bilangan halaman

halaman

pages=total%pagesSize ==0?total/pgeSize:total/pageSize+ 1;

#Halaman semasa

pageNum

Langkah-langkah

1 pergantungan pagehelper

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.5</version>
</dependency>

rrree

2. kelas entiti kacang

Entiti pengguna:

#pagehelper分页插件配置
pagehelper.helper-dialect=mysql
pagehelper.reasonable=true
pagehelper.support-methods-arguments=true
pagehelper.params=count=countSql

Kembalikan kelas entiti bahagian hadapan: termasuk data yang ditemui dan data halaman

rreee

2.lapisan pemeta:

package com.qianfeng.bean;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
 
@Data
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class Register {
    private Integer id;
 
    private String userName;
 
    private String passWord;
 
    private String rePassWord;
 
    private String idCard;
    private String gender;
 
}

3.lapisan perkhidmatan:

package com.qianfeng.bean;
import com.github.pagehelper.PageInfo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
 
import java.util.List;
 
@Data
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class RegPage {
    private PageInfo pageInfo;
    private List<Register> registers;
}

4.serviceImpl:

package com.qianfeng.mapper;
 
import com.qianfeng.bean.Register;
import org.apache.ibatis.annotations.Mapper;
 
import java.util.List;
@Mapper
public interface PageDao {
    List<Register> getAll(Integer startRow,Integer pageSize);
    long getCount();
}

5.lapisan pengendali:

package com.qianfeng.service;
 
import com.github.pagehelper.PageInfo;
import com.qianfeng.bean.RegPage;
 
public interface RegService {
    RegPage getAll(PageInfo pageInfo);
}

6 .mapper.xml

package com.qianfeng.service.serviceImpl;
 
import com.github.pagehelper.PageInfo;
import com.qianfeng.bean.RegPage;
import com.qianfeng.bean.Register;
import com.qianfeng.mapper.PageDao;
import com.qianfeng.service.RegService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.List;
 
@Service
public class RegServiceImpl implements RegService {
    @Autowired
    private PageDao pageDao;
    @Override
    public RegPage getAll(PageInfo pageInfo) {
        List<Register> all = pageDao.getAll(pageInfo.getStartRow(), pageInfo.getPageSize());//分页后的数据
        long count = pageDao.getCount();//总记录条数
        pageInfo.setTotal(count);
        //总页数
        int pages= (int) (pageInfo.getTotal()%pageInfo.getPageSize()==0?pageInfo.getTotal()/pageInfo.getPageSize():pageInfo.getTotal()/pageInfo.getPageSize()+1);
        pageInfo.setPages(pages);
 
        RegPage regPage = new RegPage();
        regPage.setPageInfo(pageInfo);
        regPage.setRegisters(all);
        return regPage;
 
    }
}

7 .application.yaml

package com.qianfeng.handler;
 
import com.github.pagehelper.PageInfo;
import com.qianfeng.bean.RegPage;
import com.qianfeng.service.RegService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
@RestController
public class RegHandler {
    @Autowired
    private RegService regService;
    @RequestMapping("/page/{pageNum}")
    public RegPage regPage(@PathVariable("pageNum") Integer pageNum){
        System.out.println(".........");
        PageInfo pageInfo = new PageInfo();
        pageInfo.setPageNum(pageNum);
        pageInfo.setPageSize(3);
        pageInfo.setStartRow((pageNum-1)*pageInfo.getPageSize());
        System.out.println("startRow" + pageInfo.getStartRow());
        return regService.getAll(pageInfo);
    }
}

8.application,properties

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.qianfeng.mapper.PageDao">
    <select id="getAll" resultType="com.qianfeng.bean.Register">
        select * from m_register limit #{startRow},#{pageSize}
    </select>
    <select id="getCount" resultType="java.lang.Long">
        select count(*) from m_register
    </select>
</mapper>

Mengenai kelas PageInfo, kod sumber adalah seperti berikut:

spring:
  datasource:
    url: jdbc:mysql:///map?serverTimezone=Asia/Shanghai&useSSL=false
    username: root
    password: 123
    driver-class-name: com.mysql.jdbc.Driver
 
    druid:
      aop-patterns: com.qianfeng.*  #监控SpringBean
      filters: stat,wall     # 底层开启功能，stat（sql监控），wall（防火墙）
 
      stat-view-servlet:   # 配置监控页功能
        enabled: true
        login-username: admin
        login-password: admin
        resetEnable: false
 
      web-stat-filter:  # 监控web
        enabled: true
        urlPattern: /*
        exclusions: '*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*'
      filter:
        stat:    # 对上面filters里面的stat的详细配置
          slow-sql-millis: 1000
          logSlowSql: true
          enabled: true
        wall:
          enabled: true
          config:
            drop-table-allow: false
  mvc:
    pathmatch:
      matching-strategy: ant_path_matcher
# mybatis的配置规则
mybatis:
  #config-location: classpath:mapper/mybatis-config.xml
  mapper-locations: classpath:mapper/*
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
#      static-locations: [classpath:/haha/]  # 静态资源路径自定义

Struktur direktori:

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