Issue in downloading zip file in Spring REST Service - spring

Question

My API is as follows:
#ApiOperation(value = "Zip of all the documents the customer attached to their application (id and loan)", notes = "", response = Void.class, tags = {
"Manage Customers/Applications",
})
#ApiResponses(value = {
#ApiResponse(code = 200, message = "OK", response = Void.class)
})
#RequestMapping(value = idPath + "/files/customer-documents/zip",
method = RequestMethod.GET)
#ResponseBody
void downloadCustomerDocumentsAsZip(HttpServletResponse response,
#ApiParam(value = "Application ID", required = true) #PathVariable(value = "applicationId")
Long applicationId);
The Rest Controller:
#Override
public void downloadCustomerDocumentsAsZip(HttpServletResponse response,
#ApiParam(value = "Application ID", required = true) #PathVariable(value = "applicationId")
Long applicationId) {
InputStream inputStream = new ByteArrayInputStream(manageApplicationsService.findCustomerDocumentsAsZip(applicationId));
response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
response.setHeader("Content-Disposition", "attachment; filename=zipFile.zip");
try {
FileCopyUtils.copy(inputStream, response.getOutputStream());
} catch (IOException e) {
e.printStackTrace();
}
}
The Response:
PK{i�Jtemp0+I�(Q(A%
Issue:
I want to download the zip file as an attachment, but the response is as above.
Note:
I tried all the download methods which are explained on Rest Download Endpoints but none of them were successful. I also add
produces = MediaType.APPLICATION_OCTET_STREAM_VALUE
to the API definition but again no success.
So, I would be so grateful if anyone could help me with their genuine solution.

Answer 1

I had the same issue. Changing Content-Type to MediaType.APPLICATION_PDF_VALUE triggered download action for me. But then "Save As" dialog display filename extension as .pdf by default.
With HttpServletResponse
response.setContentType(MediaType.APPLICATION_PDF_VALUE);
response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + filename);
response.setContentLength((int)contents.length);
try {
response.getOutputStream().write(contents);
response.getOutputStream().flush();
} catch (IOException e) {
throw new BadRequestException("Could not generate file");
}
Of if you use ResponseEntity
byte[] contents = fileContent.getBytes();
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + filename);
responseHeaders.add(HttpHeaders.CONTENT_TYPE,MediaType.APPLICATION_PDF_VALUE);
return new ResponseEntity<byte[]>(contents, responseHeaders,HttpStatus.OK);

Answer 2

You can just return a ResponseEntity<byte[]> in your controller. Add Content-Type and Content-Disposition headers to your response so that it opens properly.
public ResponseEntity<byte[]> downloadCustomerDocumentsAsZip(
#ApiParam(value = "Application ID", required = true)
#PathVariable(value = "applicationId") Long applicationId) {
byte[] bytes = manageApplicationsService.findCustomerDocumentsAsZip(applicationId);
MultiValueMap<String, String> headers = new LinkedMultiValueMap<>();
headers.add("Content-Type", "application/octet-stream");
headers.add("Content-Disposition", "attachment; filename=\"zipFile.zip\"");
return new ResponseEntity<>(bytes, headers, HttpStatus.OK);
}

Answer 3

According to HttpServletResponse doc: calling flush() commits the response. I think you need to call response.getOutputStream().flush(); if you want to use HttpServletResponse. Otherwise, Tim's answer provides an easier way to do it.

Answer 4

You can set the media type as: application/json;charset=UTF-8 by using:
HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_JSON_UTF8);