无法设法通过Servlet下载从BLOB检索的PDF

Question

I looked around and tried a few solutions I saw, but nothing seemed to work.

So here is my case :

I have a PDF file stored in my oracle database as BLOB. In my backend, I call my service in order to download that pdf (In my entity, the pdf is a byte[] ) like this :

@GET
@Path("/downloadpdf")
@Produces("application/pdf")
public HttpServletResponse downloadPdf(@Context HttpServletRequest request, @Context HttpServletResponse response) {
    try {
        UserGuideJpaService userGuideService = new UserGuideJpaServiceImpl();
        HashMap<String, Object> result = userGuideService.getPdfGuide();
        if ("0".equals(result.get("returnCode"))) {
            UserGuide userGuide = (userGuide) result.get("userGuide");
            response.setHeader("Pragma", "no-cache");
            response.setHeader("Cache-control", "private");
            response.setDateHeader("Expires", 0);
            response.setContentType("application/pdf");
            response.setHeader("Content-Disposition", "attachment; filename=\"APP - User Guide.pdf\"");

            byte[] pdf = userGuide.getPdf();

            if (pdf != null) {
                response.setContentLength(pdf.length);
                ServletOutputStream out = response.getOutputStream();
                out.write(pdf);
                out.flush();
                out.close();
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return response;
}

Back to my front-end, I have this :

NOTE : This is what my response.data looks like (it's a string) :

%PDF-1.4 %

8 0 obj << /Type /Page /Resources << /ProcSet [ /PDF /Text ] /Font 4 0 R /Shading 6 0 R /ExtGState 7 0 R

/MediaBox [0 0 595.28 864.00] /Contents 9 0 R /Parent 10 0 R >> endobj

9 0 obj << /Length 1679 /Filter [ /FlateDecode ] >> stream x X n7 ?] 84 aw =I Jr v %ڝ@ Q a s + r %E_- % {x | 1 o Oo { ߌj bCN_3 81 { ̭] 9 rXU e T]WV m q5|\\5 a Ꞽ" T0n~" O X 9 #~+ b 5 7 9 ) R/f 5xF 5 WW eA lr}A.' 7Ej iƳ ] \\ ^ +f ܦ UT < 1 , ZrE3 s 4 bzU,f 4 ̎ U *7 ̋ vN΋ 4 ' 䌜 ^ Nf#! ~2 \\G+ _ , b< 2 / WIU V 2% B {Z d H ̀R . g%@ 0Ln) 9...

And javascript side :

$scope.downloadPdf = function() {
  APIClientService.downloadPdf().then(function(response) {
    // #1
    var URL, blob, downloadLink, downloadUrl;
    downloadLink = document.createElement('a');
    downloadLink.target = '_blank';
    downloadLink.download = 'APP - User Guide.pdf';
    blob = new Blob([response.data], {
      type: 'application/pdf'
    });
    URL = window.URL || window.webkitURL;
    downloadUrl = URL.createObjectURL(blob);
    downloadLink.href = downloadUrl;
    document.body.append(downloadLink);
    downloadLink.click();
    document.body.removeChild(downloadLink);
    URL.revokeObjectURL(downloadUrl);
    // # 2
    window.open("data:application/pdf," + encodeURI(response.data));
    // # 3
    window.open("data:application/pdf," + escape(response.data));
  });
};

However, this doesn't download the file or even open it.

And I'm pretty sure the pdf is correct in the backend because I managed to get it when using :

    OutputStream out = new FileOutputStream("Test.pdf");
    out.write(pdf);
    out.close();

How can I then download the pdf form my browser ? Or at least open it ?

Edit : This is the method from APIClientService :

({
  downloadPdf: function() {
    return $http({
      method: 'GET',
      url: this.baseUrl + "/downloadpdf"
    });
  }
});

Answer 1

By default ajax requests treat you response as text, this will cause issues with non text files.

To prevent this add a binary responseType to your request, something like

({
  downloadPdf: function() {
    return $http({
      method: 'GET',
      url: this.baseUrl + "/downloadpdf",
      responseType: "blob"
    });
  }
});