SpringBoot+Mybatis分頁插件PageHelper實(shí)現(xiàn)分頁效果

更新時(shí)間：2021年11月02日 08:39:37 作者：Singinwind

這篇文章主要介紹了SpringBoot+Mybatis實(shí)現(xiàn)分頁效果,本案例是采用Mybatis分頁插件PageHelper實(shí)現(xiàn)，本文通過實(shí)例代碼給大家介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或工作具有一定的參考借鑒價(jià)值，需要的朋友可以參考下

一、項(xiàng)目結(jié)構(gòu)

按照controller,service,mapper(也叫dao)來建立項(xiàng)目，utils里面是兩個(gè)自己寫的分頁工具類?？辞?/p>

端需要什么分頁參數(shù)，你方便添加。并能返回給他

二、插件引入

1.pom.xml。引入PageHelper插件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.simons</groupId>
    <artifactId>SimonsStudio</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>SimonsStudio</name>
    <description>SimonsStudio</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--Mybatis框架-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.0</version>
        </dependency>
 
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!--pageHelper分頁插件-->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.3</version>
        </dependency>
    </dependencies>
 
    <build>
 
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
 
</project>

2.application.xml配置。我的*maper.xml都是放在resource文件夾里面的。這里有個(gè) mapper-locations一定要配你項(xiàng)目的，不懂的看我的項(xiàng)目結(jié)構(gòu)。PageHelper照著配置就行了。

server:
  port: 8080
 
spring:
    datasource:
        name: test
        url: jdbc:mysql://127.0.0.1:3306/simonsdb
        username: root
        password: root
        driver-class-name: com.mysql.jdbc.Driver
 
mybatis:
  mapper-locations: classpath:mapper/*.xml  #注意了！這個(gè)是mapper.xml的路徑。要按照目錄文件夾來命名。
  type-aliases-package: com.smions.entity  #實(shí)體類的文件夾
pagehelper: #
  helperDialect: mysql
  reasonable: true
  supportMethodsArguments: true
  params: count=countSql

三、代碼

1.mapper。習(xí)慣上從dao層寫起來。@Mapper@Component兩個(gè)注解要寫上，不然后面springboot啟動(dòng)的時(shí)候掃描不到。在Mybatis中。mapper相當(dāng)于dao層。只有接口。selectPage這個(gè)是我們要做的分頁，這個(gè)名字和Maper.xml里面的id對(duì)應(yīng)。要寫對(duì)了。

package com.simons.mapper;
 
import com.simons.entity.Student;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Component;
import java.util.List;
import java.util.Map;
 
@Mapper
@Component
public interface StudentMapper {
    /**
     * 查詢?nèi)坑脩?
     * @return
     */
    List<Map<String,Object>> selectAll();
 
    /**
     * 分頁查詢用戶
     * @return
     */
    List<Student> selectPage();
}

2.*mapper.xml。namespace對(duì)應(yīng)Java中的mapper類。id = "Base_Column_List"，是你要查詢的表里面的所有字段。記得username不要寫成name.這個(gè)我踩過好多坑。運(yùn)行的時(shí)候一直報(bào)mapper找不到對(duì)應(yīng)的方法。原因是name會(huì)被識(shí)別為關(guān)鍵字?。〔灰∶鹲ql或者java的關(guān)鍵字，不然你會(huì)哭的??！

<?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.simons.mapper.StudentMapper" >
    <sql id="Base_Column_List" >
        id,
        username,
        password
    </sql>
    <select id="selectAll" resultType="map">
        SELECT
        <include refid="Base_Column_List" />
        FROM student
    </select>
 
 
    <select id="selectPage" resultType="map">
        SELECT
        <include refid="Base_Column_List" />
        FROM student
    </select>
 
 
</mapper>

3.service.java。getPageInfo方法是重點(diǎn)。PageHelper的核心代碼就只有一句:

PageHelper.startPage(pageNum,pageSize);//開始分頁
List<Student> students = studentMapper.selectPage();//查詢數(shù)據(jù)庫返回?cái)?shù)據(jù)
PageInfo<Student> pageInfo = new PageInfo<>(students);//得到數(shù)據(jù)，里面還帶有分頁的各個(gè)參數(shù)

很簡單是不是。接下來介紹一下pageInfo自帶的分頁參數(shù):

pageNum=5, //查詢的頁數(shù)(第5頁)
pageSize=3, //每頁的大小
size=3,
startRow=13,
endRow=15,
total=22,//總數(shù)
pages=8, //總頁數(shù)：22/3=8
list=Page{count=true, pageNum=5, pageSize=3, startRow=12, endRow=15, total=22, pages=8, reasonable=true, pageSizeZero=false},
prePage=4, //前一頁
nextPage=6, //后一頁
isFirstPage=false, //是否是第一頁
isLastPage=false, //是否是最后一頁
hasPreviousPage=true, //是否有上一頁
hasNextPage=true, //是否有下一頁
navigatePages=8, //導(dǎo)航總頁數(shù)
navigateFirstPage=1, //導(dǎo)航第一頁
navigateLastPage=8, //導(dǎo)航最后一頁
navigatepageNums=[1, 2, 3, 4, 5, 6, 7, 8]//頁數(shù)碼

看完后，是不是一個(gè)很完美的插件(狗頭)。相關(guān)的分頁參數(shù)都是很齊全的。

service代碼。這里我先用getInfo拿到PageInfo。再把相關(guān)的參數(shù)和list數(shù)據(jù)拿出來。返回給controller即可。

package com.simons.service;
 
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.simons.entity.Student;
import com.simons.mapper.StudentMapper;
import com.simons.util.PageRequest;
import com.simons.util.PageResult;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
 
import java.util.List;
import java.util.Map;
 
@Service
public class StudentService{
    @Autowired
    private StudentMapper studentMapper;
 
    public List<Map<String,Object>> findAll() {
//        List<Student> students =
        List<Map<String,Object>>  map = studentMapper.selectAll();
        return map;
    }
 
    public PageResult findPage(PageRequest pageRequest) {
        PageInfo<Student> pageInfo = getPageInfo(pageRequest);
        PageResult pageResult = new PageResult();
        pageResult.setPageNum(pageInfo.getPageNum());
        pageResult.setPageSize(pageInfo.getPageSize());
        pageResult.setTotalPages(pageInfo.getPages());
        pageResult.setContent(pageInfo.getList());
        return pageResult;
    }
    
    /**
     * 調(diào)用分頁插件完成分頁
     *
     */
    public PageInfo<Student> getPageInfo(PageRequest pageRequest) {
        int pageNum = pageRequest.getPageNum();
        int pageSize = pageRequest.getPageSize();
        PageHelper.startPage(pageNum,pageSize);//核心代碼:pageHelper查詢分頁
        List<Student> students = studentMapper.selectPage();
        PageInfo<Student> pageInfo = new PageInfo<>(students);
        return pageInfo;
    }
}

4.controller層。findpage方法。查找分頁的方案。因?yàn)榉猪撏鶐в胁樵儏?shù)。這邊沒寫。

package com.simons.controller;
 
import com.simons.service.StudentService;
import com.simons.util.PageRequest;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
 
import java.util.List;
import java.util.Map;
 
//@RestController
//@RequestMapping("/student")
 
@Controller
@RequestMapping(value = {"/student"})
public class StudentController {
    @Autowired
    private StudentService studentService;
    @ResponseBody
    @RequestMapping(value="/findAll")
    public List<Map<String,Object>> findAll() {
        return studentService.findAll();
    }
 
    @ResponseBody
    @RequestMapping(value = {"/findPage"})
    public Object findPage(@RequestParam(name = "pageNum")String pageNum , @RequestParam(name = "pageSize") String pageSize) {
        PageRequest pageQuery = new PageRequest();
        pageQuery.setPageNum(Integer.parseInt(pageNum));
        pageQuery.setPageSize(Integer.parseInt(pageSize));
        return studentService.findPage(pageQuery);
    }
//    @PostMapping(value="/findPage")
//    public Object findPage(@RequestBody PageRequest pageQuery) {
//        return studentService.findPage(pageQuery);
//    }
}

5.utils類。一個(gè)是pageRequest請(qǐng)求分頁，一個(gè)是pageResult返回分頁的實(shí)體類

package com.simons.util;
 
 
import java.util.List;
/**
 * 分頁返回結(jié)果
 */
public class PageResult {
    /**
     * 當(dāng)前頁碼
     */
    private int pageNum;
    /**
     * 每頁數(shù)量
     */
    private int pageSize;
    /**
     * 記錄總數(shù)
     */
    private long totalSize;
    /**
     * 頁碼總數(shù)
     */
    private int totalPages;
    /**
     * 數(shù)據(jù)模型
     */
    private List<?> content;
    public int getPageNum() {
        return pageNum;
    }
    public void setPageNum(int pageNum) {
        this.pageNum = pageNum;
    }
    public int getPageSize() {
        return pageSize;
    }
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
    public long getTotalSize() {
        return totalSize;
    }
    public void setTotalSize(long totalSize) {
        this.totalSize = totalSize;
    }
    public int getTotalPages() {
        return totalPages;
    }
    public void setTotalPages(int totalPages) {
        this.totalPages = totalPages;
    }
    public List<?> getContent() {
        return content;
    }
    public void setContent(List<?> content) {
        this.content = content;
    }
}

package com.simons.util;
 
public class PageRequest {
    /**
     * 當(dāng)前頁碼
     */
    private int pageNum;
    /**
     * 每頁數(shù)量
     */
    private int pageSize;
 
    public int getPageNum() {
        return pageNum;
    }
    public void setPageNum(int pageNum) {
        this.pageNum = pageNum;
    }
    public int getPageSize() {
        return pageSize;
    }
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
}

6.spring項(xiàng)目啟動(dòng) application.java

package com.simons;
 
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
 
@SpringBootApplication
@MapperScan("com.simons.mapper")
//@ComponentScan(basePackages={"com.simons.*"})
public class SimonsStudioApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(SimonsStudioApplication.class, args);
    }
 
}