一、前言

最近涉及的项目如学生宿舍管理系统、题库、图片文字读取等，数据的导入导出，基本都是要用到客户熟悉的 Excel 表

下面来个 Excel导入导出简单的使用记录，使用的基础知识：

① Excel 表格数据的处理，使用了 POl
② Java 后台，依旧是的简洁有力的 SpringBoot ，用 SSM+Maven 也基本一样

二、代码与结构

1、代码结构

代码修改之前文使用 SpringBoot 写 Restful风格增删改查接口
就增加了两个 controller 层中的 Excel 数据导入导出 接口

这里写图片描述

2、代码文件

① index.html 操作模拟模拟界面

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Excel表格数据导入导出</title>
</head>
<body>

    <!-- Excel表格导出 -->
    <a href="http://localhost/student/findall">导出Excel表格内容</a>
    <hr>

    <!-- Excel表格导入 -->
    <form action="http://localhost/student/addall" method="post" enctype="multipart/form-data">
        上传Excel数据文件<input type="file" name=fileupload>
        <input type="submit" value="submit">
    </form>

</body>
</html>

②、Student.java 实体

package com.cun.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

import org.hibernate.validator.constraints.NotEmpty;

@Entity // 实体
@Table(name = "t_student") // 数据库表名
public class Student {

    @Id // 主键
    @GeneratedValue // 自增
    private Integer id;

    @NotEmpty(message = "学生姓名不能为空") // 表单验证
    @Column(length = 20) // 字段长度
    private String t_name;

    @Column(length = 20) // 字段长度
    private String major;

    public Integer getId() {
        return id;
    }

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

    public String getT_name() {
        return t_name;
    }

    public void setT_name(String t_name) {
        this.t_name = t_name;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }

}

③ dao接口 StudentDao.java

package com.cun.dao;

import org.springframework.data.jpa.repository.JpaRepository;

import com.cun.entity.Student;

/**
 * 简单的dao层只需要继承JpaRepository接口，即可，
 * 复杂sql语句再自己增加接口
 * @author linhongcun
 *
 */
public interface StudentDao extends JpaRepository<Student, Integer>{


}

④ 事务层接口 StudentService.java

package com.cun.service;

import java.util.List;

import com.cun.entity.Student;

public interface StudentService {

    public void addStudent(Student student);
    public List<Student> findAllStudent();

}

⑤ 事务层实现类 StudentServiceImpl.java

package com.cun.service.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.cun.dao.StudentDao;
import com.cun.entity.Student;
import com.cun.service.StudentService;

@Service 
public class StudentServiceImpl implements StudentService {

    @Autowired  
    private StudentDao studentDao;

    @Override
    public void addStudent(Student student) {
        // TODO Auto-generated method stub
        studentDao.save(student);
    }

    @Override
    public List<Student> findAllStudent() {
        // TODO Auto-generated method stub
        return studentDao.findAll();

    }

}

⑥控制层，操作 Excel ，StudentController.java

package com.cun.controller;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import com.cun.entity.Student;
import com.cun.service.StudentService;

@RestController
@RequestMapping("/student")
public class StudentController {

    @Autowired
    private StudentService studentservice;

    /**
     * 通过请求下载Excel表格数据
     * 
     * @param response
     * @throws IOException
     */
    @RequestMapping(value = "/findall")
    public void findAllStudent(HttpServletResponse response) throws IOException {
        Workbook wb = new HSSFWorkbook();
        String headers[] = { "id", "major", "t_name" };
        int rowIndex = 0;
        Sheet sheet = wb.createSheet();
        Row row = sheet.createRow(rowIndex++);
        for (int i = 0; i < headers.length; i++) { // 先写表头
            row.createCell(i).setCellValue(headers[i]);
        }
        List<Student> list = studentservice.findAllStudent();
        for (int i = 0; i < list.size(); i++) {
            row = sheet.createRow(rowIndex++);
            row.createCell(0).setCellValue(list.get(i).getId());
            row.createCell(1).setCellValue(list.get(i).getMajor());
            row.createCell(2).setCellValue(list.get(i).getT_name());
        }
        response.setHeader("Content-Disposition",
                "attachment;filename=" + new String("手动导出excel.xls".getBytes("utf-8"), "iso8859-1"));
        response.setContentType("application/ynd.ms-excel;charset=UTF-8");
        OutputStream out = response.getOutputStream();
        wb.write(out);
        out.flush();
        out.close();
    }

    /**
     * 必须先把文件写到本地，才能读取上传的文件的内容，因为File要用到路径，上传是没有路径的，只有文件
     * 
     * @param fileupload
     * @param request
     * @throws IOException
     */
    @PostMapping("/addall")
    public void addAllSetudent(@RequestParam("fileupload")MultipartFile fileupload, HttpServletRequest request)
            throws IOException {
        String originalFilename = fileupload.getOriginalFilename();
        String mypath = "C:\\LLLLLLLLLLLLLLLLLLL\\"+originalFilename;

        //上传到本地
        fileupload.transferTo(new File(mypath));

        //Excel读取
        POIFSFileSystem fs = new POIFSFileSystem(new FileInputStream(mypath));
        HSSFWorkbook wb = new HSSFWorkbook(fs);
        HSSFSheet hssfSheet = wb.getSheetAt(0); // 获取第一个Sheet页

        if (hssfSheet != null) {
            for (int rowNum = 1; rowNum <= hssfSheet.getLastRowNum(); rowNum++) {
                HSSFRow hssfRow = hssfSheet.getRow(rowNum);
                if (hssfRow != null) {
                    //mysql写入
                    Student student = new Student();
                    student.setId((int) hssfRow.getCell(0).getNumericCellValue());
                    student.setMajor(hssfRow.getCell(1).getStringCellValue());
                    student.setT_name(hssfRow.getCell(2).getStringCellValue());
                    studentservice.addStudent(student);
                }
            }
        }

    }

}

⑦ application.yml 配置文件

server:
  port: 80 #为了以后访问项目不用写端口号
  context-path: / #为了以后访问项目不用写项目名
spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/webapp
    username: root
    password: 123
  jpa: 
    hibernate:
      ddl-auto: update  #数据同步代码
    show-sql: true      #数据库操作时，显示sql语句

⑧ Maven 依赖 pom.xml，这里列出自己添加进去的，不含 Spring Tools 自动加入

<!-- POI -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>3.17</version>
</dependency>
<!-- JPA -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!-- MySQl -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<!-- Web -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>