SpringBoot+Mybatis分页插件PageHelper实现分页效果

<?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分页插件-->

         <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>

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！这个是mapper.xml的路径。要按照目录文件夹来命名。

   type-aliases- package : com.smions.entity  #实体类的文件夹

pagehelper: #

   helperDialect: mysql

   reasonable: true

   supportMethodsArguments: true

   params: count=countSql

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 {

     /**

      * 查询全部用户

      * @return

      */

     List<Map<String,Object>> selectAll();

     /**

      * 分页查询用户

      * @return

      */

     List<Student> selectPage();

}

<?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>

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;

     }

     /**

      * 调用分页插件完成分页

      *

      */

     public PageInfo<Student> getPageInfo(PageRequest pageRequest) {

         int pageNum = pageRequest.getPageNum();

         int pageSize = pageRequest.getPageSize();

         PageHelper.startPage(pageNum,pageSize); //核心代码:pageHelper查询分页

         List<Student> students = studentMapper.selectPage();

         PageInfo<Student> pageInfo = new PageInfo<>(students);

         return pageInfo;

     }

}

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);

//    }

}

package com.simons.util;

import java.util.List;

/**

  * 分页返回结果

  */

public class PageResult {

     /**

      * 当前页码

      */

     private int pageNum;

     /**

      * 每页数量

      */

     private int pageSize;

     /**

      * 记录总数

      */

     private long totalSize;

     /**

      * 页码总数

      */

     private int totalPages;

     /**

      * 数据模型

      */

     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 {

     /**

      * 当前页码

      */

     private int pageNum;

     /**

      * 每页数量

      */

     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;

     }

}

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);

     }

}