Java springmvc Excel(poi) 的導入導出（上傳下載）

maven-poi

  <!--excel-->
    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi</artifactId>
      <version>3.15</version>
    </dependency>
    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi-ooxml</artifactId>
      <version>3.15</version>
    </dependency>
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-lang3</artifactId>
      <version>3.3.2</version>
    </dependency>

springmvc 文件上傳限制

  <!--配置文件解析器,id名不可改，必須用這個-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="10485760"></property>
    </bean>

上傳excel 並解析excel

    <meta http-equiv="Content-Type" content="multipart/form-data; charset=utf-8" />   

    <form action="fileUpload" method="post" enctype="multipart/form-data">
         <input type="file" name="fileUpload"> <%--此處的id值，需要與對應的處理 MultipartFile 實例參數名一致--%>
         <input type="submit" value="導入文件">
    </form>

//excel文件上傳
    @RequestMapping(value = "/fileUpload")
    public String  fileUpload(HttpServletRequest request,MultipartFile fileUpload) throws IOException {
        XSSFWorkbook workbook=null;
        File file = new File("xx");
        FileInputStream fileInputStream = null;
        byte[] bytes= fileUpload.getBytes();

        OutputStream output = new FileOutputStream(file);
        BufferedOutputStream bufferedOutput = new BufferedOutputStream(output);
        bufferedOutput.write(bytes);
        fileInputStream = new FileInputStream(file);
        file.deleteOnExit();   //刪除文件
        fileUpload=null;


        BufferedInputStream bis = new BufferedInputStream(fileInputStream);
        //創建工作簿
        workbook= new XSSFWorkbook(bis);//注意07的版本使用這個
        //按索引讀取sheet表
        XSSFSheet sheet = workbook.getSheetAt(0);
        //取得所有的行數
        int rowNum = sheet.getLastRowNum();
        for (int i = 1; i <= rowNum; i++) {
            //讀取1行
            XSSFRow row = sheet.getRow(i);
            XSSFCell cell=null;
            //讀取每行的列數
            //short cellNum = row.getLastCellNum();

            Employee employee = new Employee();


            cell= row.getCell(1);
            employee.setEname(getCellValue( cell));

            Department department = new Department();
            cell= row.getCell(2);
            department.setDid(Integer.parseInt(getCellValue(cell)));
            cell= row.getCell(3);
            department.setDname(getCellValue(cell));
            cell= row.getCell(4);
            department.setDaddress(getCellValue(cell));

            employee.setDno(department);

            iEmployeeService.insertEmployee(employee);

        }

        return "index";
    }

    //excel 單元格格式
    private String getCellValue(XSSFCell cell) {
        switch (cell.getCellType()) {
            case Cell.CELL_TYPE_NUMERIC: // 數字
                // 如果爲時間格式的內容
                if (DateUtil.isCellDateFormatted(cell)) {
                    //注：format格式 yyyy-MM-dd
                    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
                    return sdf.format(cell.getDateCellValue());
                } else {
                    //有小數保留兩位，位數不夠自動忽略
                    return new DecimalFormat("#.##").format(cell.getNumericCellValue());
                }
            case Cell.CELL_TYPE_STRING: // 字符串
                return cell.getStringCellValue();
            case Cell.CELL_TYPE_BOOLEAN: // Boolean
                return cell.getBooleanCellValue() + "";
            case Cell.CELL_TYPE_FORMULA: // 公式
                return cell.getCellFormula() + "";
            case Cell.CELL_TYPE_BLANK: // 空值
                return "";
            case Cell.CELL_TYPE_ERROR: // 故障
                return "非法字符";
            default:
                return "未知類型";
        }

    }

構建excel 並下載

//導出文件    導出的文件不能直接導入，需要另存爲xlsx
    @RequestMapping("/fileDownload")
    public void fileDownload(HttpServletResponse response) throws IOException {
        //創建工作簿，SXSSFWorkbook支持大數據量的導出
        SXSSFWorkbook workbook = new SXSSFWorkbook();
        //創建sheet表
        Sheet sheet = workbook.createSheet("康舍司測試表");
        List<Employee> employees = iEmployeeService.selectEmployee(0, 0);

        //創建標題
        Row rowTitle = sheet.createRow(0);
        Cell cellTitle=null;
        cellTitle = rowTitle.createCell(0);
        cellTitle.setCellValue("eid");
        cellTitle = rowTitle.createCell(1);
        cellTitle.setCellValue("ename");
        cellTitle = rowTitle.createCell(2);
        cellTitle.setCellValue("did");
        cellTitle = rowTitle.createCell(3);
        cellTitle.setCellValue("dname");
        cellTitle = rowTitle.createCell(4);
        cellTitle.setCellValue("daddress");

        for (int i = 0; i < employees.size(); i++) {
            //創建行
            Row row = sheet.createRow(i+1);
            Cell cell =null;//創建單元格

            cell = row.createCell(0);
            cell.setCellValue(employees.get(i).getEid());
            cell = row.createCell(1);
            cell.setCellValue(employees.get(i).getEname());
            cell = row.createCell(2);
            cell.setCellValue(employees.get(i).getDno().getDid());
            cell = row.createCell(3);
            cell.setCellValue(employees.get(i).getDno().getDname());
            cell = row.createCell(4);
            cell.setCellValue(employees.get(i).getDno().getDaddress());



        }
        ServletOutputStream outputStream = response.getOutputStream();
        response.reset();  //清空輸出六

        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/force-download");
        //response.setContentType("application/octet-stream;charset=UTF-8");
        response.setHeader("Content-Disposition","attachment;filename=fileOut.xlsx");
        response.setHeader("Pargam","no-cache");
        response.setHeader("Cache-Control","no-cache");



        workbook.write(outputStream);
        workbook.close();

    }

問題：通過SXSSFWorkbook構建的excel (xlsx) 表格，導出後，該文件導入無法解析

原因：導出的excel文件頭中有問題

解決方法：將導出文件，另存爲xlsx，就可以，重新上傳