1. Need to import the jar package of PageHelper

If maven is not used, just import the jar package into the lib folder. The PageHelper plug-in has open source on github,

Address: https://github.com/pagehelper/Mybatis-PageHelper/tree/master/src/main/java/com/github/pagehelper.  

If maven is used, the plug-in can be introduced in pom.xml as follows:

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper</artifactId>
    <version>4.1.4</version>
</dependency>

2. Configure the plug-in in the global configuration file SqlMapConfig.xml of mybatis

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <plugins>
<! -- set paging plug-in -- >
        <plugin interceptor="com.github.pagehelper.PageHelper">
            <! -- set six database types: Oracle, mysql, MariaDB, SQLite, HSQLDB and PostgreSQL -- >
            <property name="dialect" value="mysql"/>
        </plugin>
    </plugins>
</configuration>

3. Add plug-ins before executing sql to complete paging function

Before executing the sql statement of the query, add a line of code PageHelper.startPage(1, 10); the first parameter represents the page number, and the second parameter represents the number of records displayed per page.

After executing the sql, the records will be paged as set in the statement. If you need to get the total number of records, you need an object of PageInfo class,

This object can get the total number of records. Let's look at the code under test.

public class TestPageHelper {
    @Test
    public void testPageHelper() {
        // Create a spring container
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:spring/applicationContext-*");
        // Get mapper proxy object from spring container
        TbItemMapper mapper =context.getBean(TbItemMapper.class);
        // Execute the query and paginate it. TbItemExample is automatically generated by reverse engineering for condition query. If it is not set here, it means unconditional
        TbItemExample example = new TbItemExample();
        //Pagination, displaying 10 pieces of data on the first page
        PageHelper.startPage(1, 10);
        List<TbItem> list =mapper.selectByExample(example);//query
        // Get commodity list
        for(TbItem item : list) {
           System.out.println(item.getTitle());
        }
        // Take page information
        PageInfo<TbItem> pageInfo = new PageInfo<TbItem>(list);
        long total = pageInfo.getTotal(); //Get total records
        System.out.println("Shared product information:" + total);
    }
}

Official documents, reference:

https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md

Pageinfo < T > contains many complex properties and methods, which can be used conveniently when paging

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package com.github.pagehelper;

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

public class PageInfo<T> implements Serializable {
    private static final long serialVersionUID = 1L;
    private int pageNum;
    private int pageSize;
    private int size;
    private String orderBy;
    private int startRow;
    private int endRow;
    private long total;
    private int pages;
    private List<T> list;
    private int firstPage;
    private int prePage;
    private int nextPage;
    private int lastPage;
    private boolean isFirstPage;
    private boolean isLastPage;
    private boolean hasPreviousPage;
    private boolean hasNextPage;
    private int navigatePages;
    private int[] navigatepageNums;

    public PageInfo() {
        this.isFirstPage = false;
        this.isLastPage = false;
        this.hasPreviousPage = false;
        this.hasNextPage = false;
    }

    public PageInfo(List<T> list) {
        this(list, 8);
    }

    public PageInfo(List<T> list, int navigatePages) {
        this.isFirstPage = false;
        this.isLastPage = false;
        this.hasPreviousPage = false;
        this.hasNextPage = false;
        if (list instanceof Page) {
            Page page = (Page)list;
            this.pageNum = page.getPageNum();
            this.pageSize = page.getPageSize();
            this.orderBy = page.getOrderBy();
            this.pages = page.getPages();
            this.list = page;
            this.size = page.size();
            this.total = page.getTotal();
            if (this.size == 0) {
                this.startRow = 0;
                this.endRow = 0;
            } else {
                this.startRow = page.getStartRow() + 1;
                this.endRow = this.startRow - 1 + this.size;
            }
        } else if (list instanceof Collection) {
            this.pageNum = 1;
            this.pageSize = list.size();
            this.pages = 1;
            this.list = list;
            this.size = list.size();
            this.total = (long)list.size();
            this.startRow = 0;
            this.endRow = list.size() > 0 ? list.size() - 1 : 0;
        }

        if (list instanceof Collection) {
            this.navigatePages = navigatePages;
            this.calcNavigatepageNums();
            this.calcPage();
            this.judgePageBoudary();
        }

    }

    private void calcNavigatepageNums() {
        int i;
        if (this.pages <= this.navigatePages) {
            this.navigatepageNums = new int[this.pages];

            for(i = 0; i < this.pages; ++i) {
                this.navigatepageNums[i] = i + 1;
            }
        } else {
            this.navigatepageNums = new int[this.navigatePages];
            i = this.pageNum - this.navigatePages / 2;
            int endNum = this.pageNum + this.navigatePages / 2;
            int i;
            if (i < 1) {
                i = 1;

                for(i = 0; i < this.navigatePages; ++i) {
                    this.navigatepageNums[i] = i++;
                }
            } else if (endNum > this.pages) {
                endNum = this.pages;

                for(i = this.navigatePages - 1; i >= 0; --i) {
                    this.navigatepageNums[i] = endNum--;
                }
            } else {
                for(i = 0; i < this.navigatePages; ++i) {
                    this.navigatepageNums[i] = i++;
                }
            }
        }

    }

    private void calcPage() {
        if (this.navigatepageNums != null && this.navigatepageNums.length > 0) {
            this.firstPage = this.navigatepageNums[0];
            this.lastPage = this.navigatepageNums[this.navigatepageNums.length - 1];
            if (this.pageNum > 1) {
                this.prePage = this.pageNum - 1;
            }

            if (this.pageNum < this.pages) {
                this.nextPage = this.pageNum + 1;
            }
        }

    }

    private void judgePageBoudary() {
        this.isFirstPage = this.pageNum == 1;
        this.isLastPage = this.pageNum == this.pages;
        this.hasPreviousPage = this.pageNum > 1;
        this.hasNextPage = this.pageNum < this.pages;
    }

    public int getPageNum() {
        return this.pageNum;
    }

    public void setPageNum(int pageNum) {
        this.pageNum = pageNum;
    }

    public int getPageSize() {
        return this.pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getSize() {
        return this.size;
    }

    public void setSize(int size) {
        this.size = size;
    }

    public String getOrderBy() {
        return this.orderBy;
    }

    public void setOrderBy(String orderBy) {
        this.orderBy = orderBy;
    }

    public int getStartRow() {
        return this.startRow;
    }

    public void setStartRow(int startRow) {
        this.startRow = startRow;
    }

    public int getEndRow() {
        return this.endRow;
    }

    public void setEndRow(int endRow) {
        this.endRow = endRow;
    }

    public long getTotal() {
        return this.total;
    }

    public void setTotal(long total) {
        this.total = total;
    }

    public int getPages() {
        return this.pages;
    }

    public void setPages(int pages) {
        this.pages = pages;
    }

    public List<T> getList() {
        return this.list;
    }

    public void setList(List<T> list) {
        this.list = list;
    }

    public int getFirstPage() {
        return this.firstPage;
    }

    public void setFirstPage(int firstPage) {
        this.firstPage = firstPage;
    }

    public int getPrePage() {
        return this.prePage;
    }

    public void setPrePage(int prePage) {
        this.prePage = prePage;
    }

    public int getNextPage() {
        return this.nextPage;
    }

    public void setNextPage(int nextPage) {
        this.nextPage = nextPage;
    }

    public int getLastPage() {
        return this.lastPage;
    }

    public void setLastPage(int lastPage) {
        this.lastPage = lastPage;
    }

    public boolean isIsFirstPage() {
        return this.isFirstPage;
    }

    public void setIsFirstPage(boolean isFirstPage) {
        this.isFirstPage = isFirstPage;
    }

    public boolean isIsLastPage() {
        return this.isLastPage;
    }

    public void setIsLastPage(boolean isLastPage) {
        this.isLastPage = isLastPage;
    }

    public boolean isHasPreviousPage() {
        return this.hasPreviousPage;
    }

    public void setHasPreviousPage(boolean hasPreviousPage) {
        this.hasPreviousPage = hasPreviousPage;
    }

    public boolean isHasNextPage() {
        return this.hasNextPage;
    }

    public void setHasNextPage(boolean hasNextPage) {
        this.hasNextPage = hasNextPage;
    }

    public int getNavigatePages() {
        return this.navigatePages;
    }

    public void setNavigatePages(int navigatePages) {
        this.navigatePages = navigatePages;
    }

    public int[] getNavigatepageNums() {
        return this.navigatepageNums;
    }

    public void setNavigatepageNums(int[] navigatepageNums) {
        this.navigatepageNums = navigatepageNums;
    }

    public String toString() {
        StringBuffer sb = new StringBuffer("PageInfo{");
        sb.append("pageNum=").append(this.pageNum);
        sb.append(", pageSize=").append(this.pageSize);
        sb.append(", size=").append(this.size);
        sb.append(", startRow=").append(this.startRow);
        sb.append(", endRow=").append(this.endRow);
        sb.append(", total=").append(this.total);
        sb.append(", pages=").append(this.pages);
        sb.append(", list=").append(this.list);
        sb.append(", firstPage=").append(this.firstPage);
        sb.append(", prePage=").append(this.prePage);
        sb.append(", nextPage=").append(this.nextPage);
        sb.append(", lastPage=").append(this.lastPage);
        sb.append(", isFirstPage=").append(this.isFirstPage);
        sb.append(", isLastPage=").append(this.isLastPage);
        sb.append(", hasPreviousPage=").append(this.hasPreviousPage);
        sb.append(", hasNextPage=").append(this.hasNextPage);
        sb.append(", navigatePages=").append(this.navigatePages);
        sb.append(", navigatepageNums=");
        if (this.navigatepageNums == null) {
            sb.append("null");
        } else {
            sb.append('[');

            for(int i = 0; i < this.navigatepageNums.length; ++i) {
                sb.append(i == 0 ? "" : ", ").append(this.navigatepageNums[i]);
            }

            sb.append(']');
        }

        sb.append('}');
        return sb.toString();
    }
}