Search code examples
javaspringspring-bootpdfswagger

preview pdf in browser from controller spring boot: Unrecognized response type; displaying content as text

I want to preview a pdf file genereted with java, but the following code gives this error

Unrecognized response type; displaying content as text.

@GetMapping("/previewPDF/{codeStudent}")
    public ResponseEntity<byte[]> previewPDF(@PathVariable("codeStudent") String code) throws IOException {
        
        byte[] pdf = //pdf content in bytes

        HttpHeaders headers = new HttpHeaders();      
        headers.add("Content-Disposition", "inline; filename=" + "example.pdf");
        headers.setContentType(MediaType.parseMediaType("application/pdf"));
        return ResponseEntity.ok().headers(headers).body(pdf); 
    }

UPDATE: here is a screenshot of the error enter image description here

Solution

  • You need to specify the response PDF Media Type for your resource.
    See RFC standart. Full list of Media Types.
    Spring documentation regarding produces Media Type.

        @GetMapping(value = "/previewPDF/{codeStudent}", produces = MediaType.APPLICATION_PDF_VALUE)
    public ResponseEntity<byte[]> previewPDF(@PathVariable("codeStudent") String code) throws IOException

    Set also PDF content type for your ResponseEntity

        @GetMapping(value = "/previewPDF/{codeStudent}", produces = MediaType.APPLICATION_PDF_VALUE)
    public ResponseEntity<byte[]> previewPDF(@PathVariable("codeStudent") String code) throws IOException {
        byte[] pdf = null;
        HttpHeaders headers = new HttpHeaders();
        String fileName = "example.pdf";
        headers.setContentDispositionFormData(fileName, fileName);        
        headers.setContentType(MediaType.APPLICATION_PDF);
        return ResponseEntity.ok().headers(headers).body(pdf);
    }