How to return binary data instead of base64 encoded byte[] in spring mvc rest controller

Question

I want to return a generated pdf file via spring-mvc-rest controller. This is a shortened version of the code I'm currently using:

@RestController
@RequestMapping("/x")
public class XController {
    @RequestMapping(value = "/", method = RequestMethod.GET)
    public ResponseEntity<byte[]> find() throws IOException {
        byte[] pdf = createPdf();

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(new MediaType("application", "pdf"));
        headers.setContentDispositionFormData("attachment", "x.pdf");
        headers.setContentLength(pdf.length);
        return new ResponseEntity<byte[]>(pdf, headers, HttpStatus.OK);
    }
}

This works almost fine, it just to return the actual byte array as base64 encoded :(

curl -i 'http://127.0.0.1:8080/app/x'

Server: Apache-Coyote/1.1
Content-Disposition: form-data; name="attachment"; filename=x.pdf"
Content-Type: application/pdf
Content-Length: 138654
Date: Fri, 08 Jan 2016 11:25:38 GMT

"JVBERi0xLjYNJeLjz9MNCjMyNCAwIG9iag [...]

(btw. the response doesn't even contain a closing " :)

Any hints appreciated!

replace RestController with the Controller and please check it.. — Nalla Srinivas, Jan 08 '16 at 12:53

score 11 · Answer 1 · edited Nov 22 '21 at 08:59

The problem is caused by Spring trying to encode the response as Json.

Your request probably specifies Accepts = "*/*" and since Spring ignores the ResponseEntity's ContentType, the best encoding is found to be application/json.

The simplest fix to this is to add a produces to your request mapping, so your code becomes:

@RestController
@RequestMapping(value = "/x",
                produces = "application/pdf") // <-- Add this
public class XController {
    @RequestMapping(value = "/", method = RequestMethod.GET)
    public ResponseEntity<byte[]> find() throws IOException {
        byte[] pdf = createPdf();

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_PDF);
        headers.setContentDispositionFormData("attachment", "x.pdf");
        headers.setContentLength(pdf.length);
        return new ResponseEntity<byte[]>(pdf, headers, HttpStatus.OK);
    }
}

Hi, Even i am trying this and working fine. No issue with the code but save as pop up is not appearing on browser. Any help? — Gowthami Reddy, Aug 02 '17 at 06:23
It won't open the dialog because application/pdf it's a type that your browser know how to handle. If you change in application/x-download it will work. — ElPysCampeador, Jul 07 '20 at 16:13

score 6 · Accepted Answer · edited May 23 '17 at 11:52

I created the example using your code, but a very similar method is doing his job in my web application:

@RequestMapping(value = "/", method = RequestMethod.GET)
public void downloadFile(HttpServletResponse response,
                         HttpServletRequest request) throws IOException
{
    byte[] pdf = createPdf();

    response.setContentType("application/x-download");
    response.setHeader("Content-Disposition", "attachment; filename=foo.pdf");
    response.setHeader("Pragma", "no-cache");
    response.setHeader("Cache-Control", "no-cache");
    response.getOutputStream().write(pdf);
}

Else you can try this answer Open ResponseEntity PDF in new browser tab

This works, but I thought there would be a more "springy"-way to do it. — J. Doe, Jan 08 '16 at 14:09

score 2 · Answer 3 · answered Apr 24 '16 at 03:17

This is my code and work fine, maybe this would can help you.

@RequestMapping(value = "/createReport", method = RequestMethod.POST,produces="application/pdf")
    @ResponseStatus(value = HttpStatus.OK)
    public ResponseEntity<byte[]> createReport(@RequestBody ReporteDTO reporteDTO) {
        byte[] outputReport = null;
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.parseMediaType("application/pdf"));
        headers.setContentDispositionFormData("inline", "archivo.pdf");
        headers.setCacheControl("must-revalidate, post-check=0, pre-check=0");
             outputReport = getFilePdf();
        ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(outputReport, headers, HttpStatus.OK);
        return response;
    }

score 1 · Answer 4 · edited Aug 02 '18 at 02:26

1

Add produces property to RequestMapping:

@RequestMapping(path = "/download", produces = "application/pdf")

edited Aug 02 '18 at 02:26

Stephen Rauch

47,830
31
106
135

answered Aug 02 '18 at 02:06

Donald John

11
4

score 0 · Answer 5 · answered Mar 03 '21 at 08:16

The answer from Rasmus Faber is very close.

In my case: I want to view a PDF generated by spring. I don't want to download it.
But I get every time the base64 encoded string, instead of my byte[].

I found out that I get the base64-string only in Firefox. So I switched to chrome, where the answer from Rasmus working fine.
Now, it works in Firefox too. But I can't say why (I changed nothing). I guess that something was cached.

For more information, this might help Incorrect content type for PDF file with Firefox

My working code with streams:

@GetMapping(path = "/demo/pdf", produces = "application/pdf")
public StreamingResponseBody getPdf(final HttpServletResponse response)  {
    response.setContentType("application/pdf");
    response.setHeader("cache-control","must-revalidate, post-check=0, pre-check=0");
    response.setHeader("Content-Disposition", "inline; filename=aCleverFileName.pdf");
    return outputStream -> this.pdfService.createPdf(outputStream);
}

How to return binary data instead of base64 encoded byte[] in spring mvc rest controller

5 Answers5

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