SpringBoot引入Pagehelper分页插件

╰+哭是因爲堅強的太久メ 2021-09-21 05:24 543阅读 0赞

> 环境版本：
> 
>  *  IDEA：IntelliJ IDEA 2018.2.4 x64
>  *  jdk：1.8
>  *  SpringBoot：2.2.5
>  *  Pagehelper：1.2.12
>  *  Mybatis：2.1.2（使用Mybatis做持久层）

## 一、SpringBoot框架搭建 ##

更多细节可以参考：https://blog.csdn.net/One\_L\_Star/article/details/103033571\#%E5%9B%9B%E3%80%81idea%E5%BF%AB%E9%80%9F%E5%88%9B%E5%BB%BASpringBoot%E9%A1%B9%E7%9B%AE

【1】点击：文件—>模块，选择 Spring Initializr，直接点击下一个  
![9F03C63C58A0478BBE8822D75E2358B7_method_download_shareKey_a597a9e333a830a70eba57f8604ba402][]

【2】这个页面选项是选择SpringBoot需要的启动依赖，在这里可以有很多选项，这里选择 Web 和 Mysql 然后点击下一步  
![488E06587AF44B85A839F6E76EB7541C_method_download_shareKey_e6e964c046603480654ab84954fd1e45][]

【3】保存路径，点击完成  
![944C752A34F6430FAE9DEC181410D081_method_download_shareKey_a5fe09089037339367a21c29c6fbd06b][]

## 二、配置 ##

### 1、在pom文件中引入Pagehelper分页插件 ###

<dependency>
        <groupId>com.github.pagehelper</groupId>
        <artifactId>pagehelper-spring-boot-starter</artifactId>
        <version>1.2.12</version>
    </dependency>

### 2、配置分页插件 ###

将application.properties配置文件改成yml后缀，即application.yml,进行如下配置

spring:
      datasource:
        url: jdbc:mysql://127.0.0.1:3306/pagehelperdemodat?useUnicode=true&characterEncoding=UTF-8&serverTimezone=CST
        username: root
        password: 806188
        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

### 3、创建数据库 ###

咱们就以用户数据库为例来进行测试，数据库创建如下：

CREATE DATABASE pagehelperdemodat;
    
    USE pagehelperdemodat;
    
    CREATE TABLE users(
        id INT PRIMARY KEY AUTO_INCREMENT COMMENT 'id主键', 
        username VARCHAR(20) NOT NULL COMMENT '用户名',
        PASSWORD  VARCHAR(20) NOT NULL COMMENT'用户密码'
    );
    
    INSERT INTO users (username,PASSWORD) VALUES("onestar","123");
    INSERT INTO users (username,PASSWORD) VALUES("twostar","456");

插入多条数据方便分页查看

![8C70DF0E4DC143A497083BEC47F2465B_method_download_shareKey_ea2c1ca74319b89b57c2247ac11deca9][]

## 三、代码编写 ##

### 1、创建用户实体类：User ###

package com.star.entity;
    
    /** * @Description: 用户实体类 * @Author: ONESTAR * @Date: Created in 22:57 2020/3/27 * @QQ: 316392836 * @URL: http://122.51.28.187:8080/ */
    public class User { 
    
        private Integer id;
        private String username;
        private String PASSWORD;
    
        public Integer getId() { 
            return id;
        }
    
        public void setId(Integer id) { 
            this.id = id;
        }
    
        public String getUsername() { 
            return username;
        }
    
        public void setUsername(String username) { 
            this.username = username;
        }
    
        public String getPASSWORD() { 
            return PASSWORD;
        }
    
        public void setPASSWORD(String PASSWORD) { 
            this.PASSWORD = PASSWORD;
        }
    
        @Override
        public String toString() { 
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", PASSWORD='" + PASSWORD + '\'' +
                    '}';
        }
    }

### 2、创建用户持久层接口：UserDao ###

package com.star.dao;
    
    import com.star.entity.User;
    import org.apache.ibatis.annotations.Select;
    
    import java.util.List;
    
    /** * @Description: 用户持久层接口 * @Author: ONESTAR * @Date: Created in 22:59 2020/3/27 * @QQ: 316392836 * @URL: http://122.51.28.187:8080/ */
    public interface UserDao { 
    
        //查询所有用户
        @Select("select * from users")
        List<User> getAllUser();
    
    }

### 3、创建业务层接口和实现类：UserService、UserServiceImpl ###

package com.star.service;
    
    import com.star.entity.User;
    
    import java.util.List;
    
    /** * @Description: 用户业务层接口 * @Author: ONESTAR * @Date: Created in 23:04 2020/3/27 * @QQ: 316392836 * @URL: http://122.51.28.187:8080/ */
    public interface UserService { 
    
        //查询所有用户
        List<User> getAllUser();
    }

package com.star.service.impl;
    
    import com.star.dao.UserDao;
    import com.star.entity.User;
    import com.star.service.UserService;
    import org.springframework.stereotype.Service;
    
    import javax.annotation.Resource;
    import java.util.List;
    
    /** * @Description: 用户业务层接口实现类 * @Author: ONESTAR * @Date: Created in 23:06 2020/3/27 * @QQ: 316392836 * @URL: http://122.51.28.187:8080/ */
    @Service
    public class UserServiceImpl implements UserService { 
    
        @Resource
        UserDao userDao;
    
    
        @Override
        public List<User> getAllUser() { 
            return userDao.getAllUser();
        }
    }

### 4、创建用户控制层：UserController ###

package com.star.controller;
    
    import com.github.pagehelper.PageHelper;
    import com.github.pagehelper.PageInfo;
    import com.star.entity.User;
    import com.star.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.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    
    import java.util.List;
    
    /** * @Description: 用户控制层 * @Author: ONESTAR * @Date: Created in 23:07 2020/3/27 * @QQ: 316392836 * @URL: http://122.51.28.187:8080/ */
    @Controller
    public class UserController { 
    
        @Autowired
        UserService userService;
    
        @GetMapping("/findUser")
        public String findUser(Model model,@RequestParam(defaultValue = "1",value = "pageNum") Integer pageNum){ 
            PageHelper.startPage(pageNum,5);
            List<User> list = userService.getAllUser();
            PageInfo<User> pageInfo = new PageInfo<User>(list);
            model.addAttribute("pageInfo",pageInfo);
            return "index";
        }
    }

在这里可以看到，PageHelper.startPage(int PageNum,int PageSize):，这个是用来设置页面的位置和展示的数据条目数的，我们设置每页展示5条数据。PageInfo用来封装页面信息，返回给前台界面，一些PageInfo的参数：

//当前页
     private int pageNum;
     //每页的数量
     private int pageSize;
     //当前页的数量
     private int size;
     //当前页展示的数据的起始行
     private int startRow;
     //当前页展示的数据的结束行
     private int endRow;
     //总记录数--所需要进行分页的数据条数
     private long total;
     //总页数
     private int pages;
     //页面展示的结果集，比如说当前页要展示20条数据，则此list为这20条数据
     private List<T> list;
     //前一页页码
     private int prePage;
     //下一页页码
     private int nextPage;
     //是否为第一页，默认为false，是第一页则设置为true
     private boolean isFirstPage ;
     //是否为最后一页默认为false，是最后一页则设置为true
     private boolean isLastPage ;
     //是否有前一页，默认为false，有前一页则设置为true
     private boolean hasPreviousPage ;
     //是否有下一页，默认为false，有后一页则设置为true
     private boolean hasNextPage ;
     //导航页码数，所谓导航页码数，就是在页面进行展示的那些1.2.3.4...
     //比如一共有分为两页数据的话，则将此值设置为2
     private int navigatePages;
     //所有导航页号，一共有两页的话则为[1,2]
     private int[] navigatepageNums;
     //导航条上的第一页页码值
     private int navigateFirstPage;
     //导航条上的最后一页页码值
     private int navigateLastPage;

### 5、添加 MapperScan 注解 ###

修改 Application ，在类前添加 MapperScan 注解，修改后如下：

package com.star;
    
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    @MapperScan({ "com.star.dao"})
    public class PagehelperdemoApplication { 
    
        public static void main(String[] args) { 
            SpringApplication.run(PagehelperdemoApplication.class, args);
        }
    
    }

### 6、创建index.xml页面 ###

<!DOCTYPE html>
    <html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
    <head>
        <meta charset="UTF-8">
        <title>分页测试</title>
    </head>
    <body>
    <H3>查询所有用户</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>当前 <span th:text="${pageInfo.pageNum}"></span> 页,总 <span th:text="${pageInfo.pages}"></span> 页,共 <span th:text="${pageInfo.total}"></span> 条记录</p>
        <a th:href="@{/findUser}">首页</a>
        <a th:href="@{/findUser(pageNum=${pageInfo.hasPreviousPage}?${pageInfo.prePage}:1)}">上一页</a>
        <a th:href="@{/findUser(pageNum=${pageInfo.hasNextPage}?${pageInfo.nextPage}:${pageInfo.pages})}">下一页</a>
        <a th:href="@{/findUser(pageNum=${pageInfo.pages})}">尾页</a>
    </body>
    </html>

## 四、运行测试 ##

启动 SpringBoot 工程，在浏览器输入：http://localhost:8080/findUser ，可以看到网页显示用户信息表格，点击上一页下一页可以进行页面切换

![108B73E270194878A9F97DA90871C04F_method_download_shareKey_03a25644aa7a9ecb2ac693beb8f32421][]

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