Use of PageHelper

PageHelper Integrate SpringBoot

1、 Create project

Create a springboot project

Import correlation dependency

<dependencies>
  <!--thymeleaf-->
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
  </dependency>

  <!--web-->
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>

  <!-- Database driven -->
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
  </dependency>

  <!--lombok Use -->
  <dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
  </dependency>

  <!--pagehelper-->
  <!--  Paging plug-ins  -->
  <dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.2.13</version>
  </dependency>

  <!-- Integrate mybatis-->
  <dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.4</version>
  </dependency>

  <!-- test -->
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
  </dependency>


</dependencies>

Create directory structure

establish application.yml file , And add the following configuration

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/pagehelperdemodat?useUnicode=true&characterEncoding=UTF-8
    username: root
    password: th123456
    driver-class-name: com.mysql.cj.jdbc.Driver

  thymeleaf:
    prefix: classpath:/templates/
    check-template-location: true
    suffix: .html
    mode: HTML
    encoding: UTF-8
    cache: false

mybatis:
  mapper-locations: classpath*:mapper/*.xml pagehelper: helper-dialect: mysql params: count=countSql reasonable: true support-methods-arguments: true 

2、 Create database

CREATE DATABASE pagehelperdemodat;

USE pagehelperdemodat;

CREATE TABLE users(
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT 'id Primary key ', 
    username VARCHAR(20) NOT NULL COMMENT ' user name ',
    PASSWORD  VARCHAR(20) NOT NULL COMMENT' User password '
);
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 1","123456");
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 2","123456");
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 3","123456");
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 4","123456");
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 5","123456");
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 6","123456");
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 7","123456");
INSERT INTO users (username,PASSWORD) VALUES(" Xiaokaixin 8","123456");

3、 Contents of relevant documents

User.java

package com.xiaokaixin.pagehelper.entity;

import lombok.AllArgsConstructor;
import lombok.Data;

/** * @Author xiaokaixin * @Date 2021/9/11 18:01 * @Version 1.0 */
@Data
@AllArgsConstructor
public class User {
    

    private Integer id;
    private String username;
    private String password;
}

UserDao.java

package com.xiaokaixin.pagehelper.dao;

import com.xiaokaixin.pagehelper.entity.User;

import java.util.List;

/** * @Author xiaokaixin * @Date 2021/9/11 18:01 * @Version 1.0 */
public interface UserDao {
    

    //  Query so users 
    List<User> getAllUser();
}

UserMapper.xml

<?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.xiaokaixin.pagehelper.dao.UserDao">
    <select id="getAllUser" resultType="com.xiaokaixin.pagehelper.entity.User">
        select * from  users
    </select>
</mapper>

UserService

package com.xiaokaixin.pagehelper.service;

import com.xiaokaixin.pagehelper.entity.User;

import java.util.List;

/** * @Author xiaokaixin * @Date 2021/9/11 18:05 * @Version 1.0 */
public interface UserService  {
    

    //  Query so users 
    List<User> getAllUser();
}

UserServiceImpl

package com.xiaokaixin.pagehelper.service.impl;

import com.xiaokaixin.pagehelper.dao.UserDao;
import com.xiaokaixin.pagehelper.entity.User;
import com.xiaokaixin.pagehelper.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

/** * @Author xiaokaixin * @Date 2021/9/11 18:05 * @Version 1.0 */
@Service
public class UserServiceImpl implements UserService {
    

    @Autowired
    UserDao userDao;

    @Override
    public List<User> getAllUser() {
    
        return userDao.getAllUser();
    }
}

UserController

package com.xiaokaixin.pagehelper.controller;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.xiaokaixin.pagehelper.entity.User;
import com.xiaokaixin.pagehelper.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;

import java.util.List;

/** * @Author xiaokaixin * @Date 2021/9/11 18:08 * @Version 1.0 */
@Controller
public class UserController {
    

    @Autowired
    UserService userService;


    @GetMapping("/")
    public String findUser(Model model, @RequestParam(defaultValue = "1",value = "pageNum") Integer pageNum){
    
        String orderBy = "id asc";
        PageHelper.startPage(pageNum,5,orderBy);
        List<User> list = userService.getAllUser();
        PageInfo<User> pageInfo = new PageInfo<User>(list);
        model.addAttribute("pageInfo",pageInfo);
        return "index";
    }
}

4、 Description of relevant parameters

// The current page 
 private int pageNum;

 // The number of pages 
 private int pageSize;

 // Number of current pages 
 private int size;

 // The starting line of the data displayed on the current page 
 private int startRow;

 // The end line of the data displayed on the current page 
 private int endRow;

 // Total number of records -- The number of data pieces that need to be paged 
 private long total;

 // Total number of pages 
 private int pages;

 // The result set displayed on the page , For example, the current page should be displayed 20 Data , Then this list For this 20 Data 
 private List<T> list;

 // Page number of the previous page 
 private int prePage;

 // Next page number 
 private int nextPage;

 // Is it the first page , The default is false, The first page is set to true
 private boolean isFirstPage ;

 // If it is the last page, the default is false, The last page is set to true
 private boolean isLastPage ;

 // Is there a previous page , The default is false, The previous page is set to true
 private boolean hasPreviousPage ;

 // Is there a next page , The default is false, The next page is set to true
 private boolean hasNextPage ;

 // Number of navigation pages , The so-called navigation page number , Those displayed on the page 1.2.3.4...
 // For example, if there are two pages of data , Set this value to 2
 private int navigatePages;

 // All navigation page numbers , A total of two pages is [1,2]
 private int[] navigatepageNums;
 // The first page number value on the navigation bar 
 private int navigateFirstPage;

 // The last page number on the navigation bar 
 private int navigateLastPage;

5、index.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
  <meta charset="UTF-8">
  <title> Paging testing </title>
</head>
<body>
<H3> Query all users </H3>
<table border="1">
  <tr>
    <th>id</th>
    <th>name</th>
    <th>password</th>
  </tr>
  <tr th:each="user:${pageInfo.list}">
    <td th:text="${user.id}"></td>
    <td th:text="${user.username}"></td>
    <td th:text="${user.password}"></td>
  </tr>
</table>
<p> At present  <span th:text="${pageInfo.pageNum}"></span>  page , total  <span th:text="${pageInfo.pages}"></span>  page , common  <span th:text="${pageInfo.total}"></span>  Bar record </p>
<a th:href="@{/}"> home page </a>
<a th:href="@{/(pageNum=${pageInfo.hasPreviousPage}?${pageInfo.prePage}:1)}"> The previous page </a>
<a th:href="@{/(pageNum=${pageInfo.hasNextPage}?${pageInfo.nextPage}:${pageInfo.pages})}"> The next page </a>
<a th:href="@{/(pageNum=${pageInfo.pages})}"> Tail page </a>
</body>
</html>

6、 Final effect