SpringBoot搭配PageHelper分頁插件

1、SpringBoot框架搭建

【1】點擊：文件--->模塊，選擇 Spring Initializr，直接點擊下一個

【2】這個頁面選項是選擇SpringBoot須要的啓動依賴，在這裏能夠有不少選項，這裏選擇 Web 和 Mysql 而後點擊下一步

【3】保存路徑，點擊完成

2、配置

一、在pom文件中引入Pagehelper分頁插件

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

二、配置分頁插件

將application.properties配置文件改爲yml後綴，即application.yml,進行以下配置

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

三、建立數據庫

我們就以用戶數據庫爲例來進行測試，數據庫建立以下：

CREATE DATABASE pagehelperdemodat;

USE pagehelperdemodat;

CREATE TABLE users(
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT 'id主鍵', 
    username VARCHAR(20) NOT NULL COMMENT '用戶名',
    PASSWORD  VARCHAR(20) NOT NULL COMMENT'用戶密碼'
);

INSERT INTO users (username,PASSWORD) VALUES("onestar","123");
INSERT INTO users (username,PASSWORD) VALUES("twostar","456");

插入多條數據方便分頁查看

3、代碼編寫

一、建立用戶實體類：User

package com.star.entity;

/**
 * @Description: 用戶實體類
 * @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 + '\'' +
                '}';
    }
}

二、建立用戶持久層接口：UserDao

package com.star.dao;

import com.star.entity.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

/**
 * @Description: 用戶持久層接口
 * @Author: ONESTAR
 * @Date: Created in 22:59 2020/3/27
 * @QQ: 316392836
 * @URL: http://122.51.28.187:8080/
 */
public interface UserDao {

    //查詢全部用戶
    @Select("select * from users")
    List<User> getAllUser();

}

三、建立業務層接口和實現類：UserService、UserServiceImpl

package com.star.service;

import com.star.entity.User;

import java.util.List;

/**
 * @Description: 用戶業務層接口
 * @Author: ONESTAR
 * @Date: Created in 23:04 2020/3/27
 * @QQ: 316392836
 * @URL: http://122.51.28.187:8080/
 */
public interface UserService {

    //查詢全部用戶
    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: 用戶業務層接口實現類
 * @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();
    }
}

四、建立用戶控制層：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: 用戶控制層
 * @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";
    }
}

在這裏能夠看到，PageHelper.startPage(int PageNum,int PageSize):，這個是用來設置頁面的位置和展現的數據條目數的，咱們設置每頁展現5條數據。PageInfo用來封裝頁面信息，返回給前臺界面，一些PageInfo的參數：

//當前頁
 private int pageNum;
 //每頁的數量
 private int pageSize;
 //當前頁的數量
 private int size;
 //當前頁展現的數據的起始行
 private int startRow;
 //當前頁展現的數據的結束行
 private int endRow;
 //總記錄數--所須要進行分頁的數據條數
 private long total;
 //總頁數
 private int pages;
 //頁面展現的結果集，好比說當前頁要展現20條數據，則此list爲這20條數據
 private List<T> list;
 //前一頁頁碼
 private int prePage;
 //下一頁頁碼
 private int nextPage;
 //是否爲第一頁，默認爲false，是第一頁則設置爲true
 private boolean isFirstPage ;
 //是否爲最後一頁默認爲false，是最後一頁則設置爲true
 private boolean isLastPage ;
 //是否有前一頁，默認爲false，有前一頁則設置爲true
 private boolean hasPreviousPage ;
 //是否有下一頁，默認爲false，有後一頁則設置爲true
 private boolean hasNextPage ;
 //導航頁碼數，所謂導航頁碼數，就是在頁面進行展現的那些1.2.3.4...
 //好比一共有分爲兩頁數據的話，則將此值設置爲2
 private int navigatePages;
 //全部導航頁號，一共有兩頁的話則爲[1,2]
 private int[] navigatepageNums;
 //導航條上的第一頁頁碼值
 private int navigateFirstPage;
 //導航條上的最後一頁頁碼值
 private int navigateLastPage;

五、添加 MapperScan 註解

修改 Application ，在類前添加 MapperScan 註解，修改後以下：

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);
    }

}

六、建立index.xml頁面

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>分頁測試</title>
</head>
<body>
<H3>查詢全部用戶</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>當前 <span th:text="${pageInfo.pageNum}"></span> 頁,總 <span th:text="${pageInfo.pages}"></span> 頁,共 <span th:text="${pageInfo.total}"></span> 條記錄</p>
    <a th:href="@{/findUser}">首頁</a>
    <a th:href="@{/findUser(pageNum=${pageInfo.hasPreviousPage}?${pageInfo.prePage}:1)}">上一頁</a>
    <a th:href="@{/findUser(pageNum=${pageInfo.hasNextPage}?${pageInfo.nextPage}:${pageInfo.pages})}">下一頁</a>
    <a th:href="@{/findUser(pageNum=${pageInfo.pages})}">尾頁</a>
</body>
</html>

4、運行測試

啓動 SpringBoot 工程，在瀏覽器輸入：http://localhost:8080/findUser ，能夠看到網頁顯示用戶信息表格，點擊上一頁下一頁能夠進行頁面切換