通过Ajax下载文件

Question

I need to download file from server via ajax. The problem is that the file is not stored on server. My java-based backend automatically generates file from request parameters and returns it in response body:

  @RequestMapping(value = "/download", method = RequestMethod.GET)
  public void download(@RequestParam String description, @RequestParam Long logId, HttpServletResponse response) {
    try {
      InputStream fileContent = // getting file as byte stream
      response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
      response.setHeader("Content-Disposition", "attachment; filename=file.zip");
      ServletOutputStream responseOutputStream = response.getOutputStream();
      org.apache.commons.io.IOUtils.copy(fileContent, responseOutputStream);
      response.flushBuffer();
    } catch (IOException e) {
      logger.error("Attempt to download file failed", e);
    }
  }

So i need to handle it and allow user to download file. My client side contains this:

$.ajax({
  type: "GET",
  url: "/download",
  data: {
    description: "test",
    logId: 123
  },
  success: function(data) {
    var blob = new Blob([data]);
    var link = document.createElement('a');
    link.href = window.URL.createObjectURL(blob);
    link.download = "file.zip";
    link.click();
  }
})

Controller returns file, but then nothing happens. What am i doing wrong?

Answer 1

Don't make an AJAX call, but rather set the window's href to point to URL for downloading the file. Then change the content type of the response to application/x-download and set the header of the response to be Content-disposition:

response.setContentType("application/x-download");
response.setHeader("Content-disposition", "attachment; filename=" + fileName);
response.flushBuffer();

function download(fileName) {
    window.location.href = "/download?description=test&logId=123";
}

Also, have a look at this SO post which addresses a similar problem to the one you have.