使用apache poi下载Excel

Question

我希望在用户调用此方法时下载 excel 文件。文件下载成功，但这是在项目的 classPath 中创建另一个 excel 文件。谁能帮我避免创建这个classPath文件。 提前致谢。

@Override
    public void downloadExcel(HttpServletRequest request,HttpServletResponse response) throws IOException { 

              File file = new File("Segmentdetail.xlsx"); 

              XSSFWorkbook workbook = new XSSFWorkbook(); 
              XSSFSheet spreadsheet = workbook.createSheet("SegmentLogs Info");
              spreadsheet.setDefaultColumnWidth(20);
             .....Here is the logic for generating sheet which is quite big so iam skipping it.

             }           
             FileOutputStream out = new FileOutputStream(file);
             workbook.write(out);
             downloadFile(file,response);
             out.close();
             workbook.close();

    }

    private void downloadFile(File file, HttpServletResponse response){

        try {         
            response.setContentType("application/vnd.ms-excel");
            response.addHeader("content-disposition", "attachment; filename=Segmentdetail.xlsx");
            response.setHeader("Pragma", "public");
            response.setHeader("Cache-Control", "no-store");
            response.addHeader("Cache-Control", "max-age=0");
            FileInputStream fin = null;
            try {
                fin = new FileInputStream(file);
            } catch (final FileNotFoundException e) {
                e.printStackTrace();
            }
            final int size = 1024;
            try {
                response.setContentLength(fin.available());
                final byte[] buffer = new byte[size];
                ServletOutputStream outputStream = null;

                outputStream = response.getOutputStream();
                int length = 0;
                while ((length = fin.read(buffer)) != -1) {
                    outputStream.write(buffer, 0, length);
                }
                fin.close();
                outputStream.flush();
                outputStream.close();
            } catch (final IOException e) {
                e.printStackTrace();
            }
        }catch (final Exception ex){
            ex.printStackTrace();
    }

}

Answer 1

为您要写入 excel 的文件使用绝对路径：

File file = new File(      "C:\\Segmentdetail.xlsx"); // windows
File file = new File("/home/usr/Segmentdetail.xlsx"); // unix    

合理的添加是使用变量：

File file = new File(System.getenv("user.home"), "Segmentdetail.xlsx");

您当然也可以定义自定义变量并使用它。

Answer 2

因为您正在使用以下命令创建文件

File file = new File("Segmentdetail.xlsx"); 

它将在类路径中生成文件

下载时最好给出文件路径和相同的文件路径

File file = new File("c://Segmentdetail.xlsx");