1 下載jar包

        <!-- excel匯出工具 -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.17</version>
        </dependency>

2 匯出Excel

package com.briup.apps.poll.web.controller;

import
 
 java.io.BufferedOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
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.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import
 
 org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;

import com.briup.apps.poll.bean.Answer;
import com.briup.apps.poll.service.IAnswerService;
import com.briup.apps.poll.util.MsgResponse;

@Controller
@RequestMapping("/excel")
public class ExcelController extends BaseController{

    @Autowired
    private IAnswerService answerService;

    /***
     * 下載Excel
     * @throws IOException
     */
    @GetMapping("download")
    public void download() throws IOException{

        HSSFWorkbook workbook = new HSSFWorkbook();
        //建立一個Excel表單,引數為sheet的名字
        HSSFSheet sheet = workbook.createSheet("課調答卷表");

        //建立表頭
        setTitle(workbook, sheet);
        List<Answer> answers = answerService.findAll();

        //新增資料行，並且設定單元格資料
        int rowNum = 1;
        for (Answer answer:answers) {
            HSSFRow row = sheet.createRow(rowNum);
            row.createCell(0).setCellValue(answer.getId());
            row.createCell(1).setCellValue(answer.getSelections());
            row.createCell(2).setCellValue(answer.getCheckes());
            row.createCell(3).setCellValue(answer.getContent());
            rowNum++;
        }
        String fileName = "survey-answer.xlsx";
        //清空response  
        response.reset();  
        //設定response的Header  
        response.addHeader("Content-Disposition", "attachment;filename="+ fileName);  
        OutputStream os = new BufferedOutputStream(response.getOutputStream());  
        response.setContentType("application/vnd.ms-excel;charset=gb2312"); 
        //將excel寫入到輸出流中
        workbook.write(os);
        os.flush();
        os.close();
    }

    /***
     * 設定表頭
     * @param workbook
     * @param sheet
     */
    private void setTitle(HSSFWorkbook workbook, HSSFSheet sheet){
        HSSFRow row = sheet.createRow(0);
        //設定列寬，setColumnWidth的第二個引數要乘以256，這個引數的單位是1/256個字元寬度
        sheet.setColumnWidth(0, 10*256);
        sheet.setColumnWidth(1, 20*256);
        sheet.setColumnWidth(2, 20*256);
        sheet.setColumnWidth(3, 100*256);

        //設定為居中加粗
        HSSFCellStyle style = workbook.createCellStyle();
        HSSFFont font = workbook.createFont();
        font.setBold(true);
        style.setFont(font);

        HSSFCell cell;
        cell = row.createCell(0);
        cell.setCellValue("序號");
        cell.setCellStyle(style);

        cell = row.createCell(1);
        cell.setCellValue("單選");
        cell.setCellStyle(style);

        cell = row.createCell(2);
        cell.setCellValue("多選");
        cell.setCellStyle(style);

        cell = row.createCell(3);
        cell.setCellValue("簡答");
        cell.setCellStyle(style);
    }
}

匯出的結果

再將此Excel讀取，程式碼如下：

3 匯入Excel

@PostMapping("upload")
    public MsgResponse upload(MultipartFile file) {
        if (file==null) {
            return error("file不能為空");
        }
        List<Answer> answers = new ArrayList<>();
        try {
            HSSFWorkbook workbook = new HSSFWorkbook(new POIFSFileSystem(file.getInputStream()));
            //有多少個sheet
            int sheets = workbook.getNumberOfSheets();
            for (int i = 0; i < sheets; i++) {
                HSSFSheet sheet = workbook.getSheetAt(i);
                //獲取多少行
                int rows = sheet.getPhysicalNumberOfRows();
                Answer answer = null;
                //遍歷每一行，注意：第 0 行為標題
                for (int j = 1; j < rows; j++) {
                    answer = new Answer();
                     //獲得第 j 行
                    HSSFRow row = sheet.getRow(j);
                    answer.setSelections(row.getCell(1).getStringCellValue());//單選
                    answer.setCheckes(row.getCell(2).getStringCellValue());//多選
                    answer.setContent(row.getCell(3).getStringCellValue());//簡答
                    answers.add(answer);
                }
            }

        } catch (IOException e) {
            logger.error(e.getMessage(),e);
            return error(e.getMessage());
        }
        return success(answers);
    }

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