Java HttpServlet 如何下载excel文件
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Java HttpServlet how to download excel file
提问by MeesterPatat
I am trying to add a function to my web app which lets the users download an excel file.
我正在尝试向我的 Web 应用程序添加一个功能，该功能允许用户下载 Excel 文件。
I'm trying to achieve this with the following code:
我正在尝试使用以下代码实现这一目标：
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) {
File file = new File("d:/test/test.xls");
response.setContentType("application/xls");
response.addHeader("Content-Disposition", "attachment; filename=test.xls");
response.setContentLength((int) file.length());
try {
FileInputStream fileInputStream = new FileInputStream(file);
OutputStream responseOutputStream = response.getOutputStream();
int bytes;
while ((bytes = fileInputStream.read()) != -1) {
responseOutputStream.write(bytes);
}
fileInputStream.close();
responseOutputStream.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
I'm able to download the excel file with the above code, however the file is corrupted. If I open it with microsoft excel, I get a popup with the message:
我可以使用上述代码下载excel文件，但是文件已损坏。如果我用 microsoft excel 打开它，我会收到一个带有消息的弹出窗口：
"the file format and extension of don't match. the file could be corrupted or unsafe".
“文件格式和扩展名不匹配。文件可能已损坏或不安全”。
And the excel file is empty.
并且excel文件是空的。
After running the code, the original file(d:/test/test.xls) gets also corrupted.
运行代码后，原始文件（d:/test/test.xls）也被损坏。
What am I doing wrong?
我究竟做错了什么？
回答by Buhake Sindi
The official MIME type for Excel file .xlsis application/vnd.ms-exceland for .xlsxis application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.
官方的MIME类型的Excel文件.xls是application/vnd.ms-excel和.xlsxIS application/vnd.openxmlformats-officedocument.spreadsheetml.sheet。
Also, I would suggest doing response.reset()prior to writing to the output stream and responseOutputStream.flush()(important) prior to closing the response.
另外，我建议response.reset()在写入输出流responseOutputStream.flush()之前和（重要）在关闭response.
回答by K M PATEL
Try below code :
试试下面的代码：
File file = null;
InputStream in = null;
OutputStream outstream = null;
try {
response.reset();
in = new FileInputStream(file);
response.setContentType("application/vnd.ms-excel");
response.addHeader("content-disposition", "attachment; filename=data.xls");
outstream = response.getOutputStream();
IOUtils.copyLarge(in, outstream);
}
catch (Exception e) {
out.write("Unable to download file");
}finally {
IOUtils.closeQuietly(outstream);
IOUtils.closeQuietly(in);
IOUtils.closeQuietly(out);
if (file != null)
file.delete();
}
dont forgot to add apache commons-io-2.4 in your dependency
不要忘记在您的依赖项中添加 apache commons-io-2.4
