Mybatis完成分页查询

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最新推荐文章于 2025-05-25 11:45:00 发布

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分类专栏： Mybatis

本文链接：https://blog.youkuaiyun.com/JAVA_I_want/article/details/100713234

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运用IDEA进行Mybatis分页查询
可以作为熟悉IDEA开发软件，熟悉Mybatis的一个案例.

数据库（Mysql）设计:
增加了测试数据

create table people(
id int(10) primary key auto_increment COMMENT '编号',
name varchar(20) COMMENT '姓名',
age int(3) COMMENT '年龄'
)comment '人员信息表';

select * from people
insert into people values(default,'张三',21);
insert into people values(default,'李四',22)
insert into people values(default,'李四1',22);
insert into people values(default,'李四2',22);
insert into people values(default,'李四3',22);
insert into people values(default,'李四4',22);
insert into people values(default,'李四5',22);
insert into people values(default,'李四6',22);
insert into people values(default,'李四7',22);
insert into people values(default,'李四8',22);

1.需要导入的jar包：
在这里插入图片描述
2.Mybatis.xml

<?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>
    <!--全局环境配置-->
    <settings>
        <setting name="logImpl" value="LOG4J"/>
    </settings>
    <!--别名-->
    <typeAliases>
        <!--<typeAlias type="com.wj.pojo.People" alias="People"/>-->
        <package name="com.wj.pojo"/>
    </typeAliases>

    <!--default引用environment的id,表示当前使用的环境-->
    <environments default="default">
        <!--声明可能使用的环境-->
        <environment id="default">
            <!--使用原生JDBC事务-->
            <transactionManager type="JDBC"></transactionManager>
            <!--数据库连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/ssm"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/wj/mapper/PeopleMapper.xml"/>
    </mappers>
</configuration>

3.peopleMapper.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.wj.mapper.PeopleMapper">
    <select id="selByPage" resultType="People" parameterType="map">
        select * from people limit #{pageStart},#{pageSize};
    </select>
    <select id="selCount" resultType="long">
        select count(*) from people
    </select>
    
</mapper>

4.PeopleService.java (interface)

package com.wj.com.wj.service;

import com.wj.pojo.PageInfo;

/**
 * @Auther: wj
 * @Date: 2019/9/10
 * @Description: com.wj.com.wj.service
 * @version: 1.0
 */
public interface PeopleService {
    /**
     * 分页显示
     * @param pageSize 每页显示个数
     * @param pageNumber 显示页数
     * @return
     */
    PageInfo showPage(int pageSize,int pageNumber);
}

5.PeopleServiceImpl.java

package com.wj.com.wj.service.Impl;

import com.wj.com.wj.service.PeopleService;
import com.wj.pojo.PageInfo;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;


/**
 * @Auther: wj
 * @Date: 2019/9/10
 * @Description: com.wj.com.wj.service.Impl
 * @version: 1.0
 */
public class PeopleServiceIml implements PeopleService {
    InputStream is=null;
    SqlSessionFactory factory=null;
    SqlSession session=null;
    @Override
    public PageInfo showPage(int pageSize, int pageNumber) {
        try {
             is = Resources.getResourceAsStream("mybatis.xml");
             factory = new SqlSessionFactoryBuilder().build(is);
             session = factory.openSession();
        } catch (IOException e) {
            e.printStackTrace();
        }
        PageInfo pi=new PageInfo();
        pi.setPageNumber(pageNumber);
        pi.setPageSize(pageSize);
        Map<String,Integer>map=new HashMap();
        map.put("pageSize",pageSize);
        map.put("pageStart",pageSize*(pageNumber-1));

        pi.setList(session.selectList("com.wj.mapper.PeopleMapper.selByPage",map));
        //总条数
        long count = session.selectOne("com.wj.mapper.PeopleMapper.selCount");
        pi.setTotal(count%pageSize==0?count/pageSize:count/pageSize+1);

        return pi;
    }
}

6.ShowPageController.java

package com.wj.controller;

import com.wj.com.wj.service.Impl.PeopleServiceIml;
import com.wj.com.wj.service.PeopleService;
import com.wj.pojo.PageInfo;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Auther: wj
 * @Date: 2019/9/10
 * @Description: com.wj.controller
 * @version: 1.0
 */
@WebServlet("/page")
public class ShowPageController extends HttpServlet{

    private PeopleService peopleServiceImpl=new PeopleServiceIml();
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        //第一次访问验证,如果没有传递参数，设置默认值
        String pageSizeStr=req.getParameter("pageSize");
        int pageSize=2;
        if(pageSizeStr!=null&&!pageSizeStr.equals("")){
            pageSize=Integer.parseInt(pageSizeStr);
        }

        String pageNumberStr=req.getParameter("pageNumber");
        int pageNumber=1;
        if(pageNumberStr!=null&&!pageNumberStr.equals("")){
            pageNumber=Integer.parseInt(pageNumberStr);
        }

        PageInfo pi = peopleServiceImpl.showPage(pageSize, pageNumber);
        req.setAttribute("PageInfo",pi);
        req.getRequestDispatcher("/index.jsp").forward(req,resp);
    }
}

实体类1：People.java

package com.wj.pojo;

/**
 * @Auther: wj
 * @Date: 2019/9/8
 * @Description: com.wj.pojo
 * @version: 1.0
 */
public class People {
    private int id;
    private String name;
    private int age;

    public People(){

    }
    public People(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "People{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

实体类2：PageInfo.java

package com.wj.pojo;

import java.util.List;

/**
 * @Auther: wj
 * @Date: 2019/9/10
 * @Description: com.wj.pojo
 * @version: 1.0
 */
public class PageInfo {

    private int pageSize;
    private int pageNumber;
    private long total;//总页数
    private List<?> list;//当前页显示数据

    public int getPageSize() {
        return pageSize;
    }

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

    public int getPageNumber() {
        return pageNumber;
    }

    public void setPageNumber(int pageNumber) {
        this.pageNumber = pageNumber;
    }

    public long getTotal() {
        return total;
    }

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

    public List<?> getList() {
        return list;
    }

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

    public PageInfo() {
    }

    public PageInfo(int pageSize, int pageNumber, long total, List<?> list) {
        this.pageSize = pageSize;
        this.pageNumber = pageNumber;
        this.total = total;
        this.list = list;
    }

    @Override
    public String toString() {
        return "PageInfo{" +
                "pageSize=" + pageSize +
                ", pageNumber=" + pageNumber +
                ", total=" + total +
                ", list=" + list +
                '}';
    }
}

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <table border="1px">
        <tr>
            <th>编号</th>
            <th>姓名</th>
            <th>年龄</th>
        </tr>
        <c:forEach items="${PageInfo.list}" var="pi">
            <tr>
                <td>${pi.id}</td>
                <td>${pi.name}</td>
                <td>${pi.age}</td>
            </tr>
        </c:forEach>
    </table>
    <a href="page?pageNumber=${PageInfo.pageNumber-1}&pageSize=${PageInfo.pageSize}"
     <c:if test="${PageInfo.pageNumber<=1}">
         οnclick="javaScript:return false;"
     </c:if>
    >上一页</a>
    <a href="page?pageNumber=${PageInfo.pageNumber+1}&pageSize=${PageInfo.pageSize}"
    <c:if test="${PageInfo.pageNumber>=PageInfo.total}">
        οnclick="javaScript:return false;"
    </c:if>
    >下一页</a>
</body>
</html>