Download PDF file from through MobileFirst Adapter

I am building an application to download the PDF file from out back-end server. I have written following code:

On Backend Server, following is the method:

        @POST
        @Consumes(MediaType.APPLICATION_JSON)
        @Produces("application/pdf")
        public Response download() {
                ResponseBuilder response = Response.ok((Object) new File("myFile.pdf"));
                response.header("Content-Disposition", "attachment; filename=myFile.pdf");
                Response responseBuilder = response.build();
                return responseBuilder;

        }

I am calling this rest method from my adapter as:

function downloadFile(){
            var input = {
                    method              : 'post',
                    returnedContentType : "plain",
                    path                : "getfiles",
                    body                : {
                        contentType : 'application/json;charset=utf-8',
                        content     : JSON.stringify({username: "testuser"})
                    }

            };
            var response = WL.Server.invokeHttp(input);
            return response;
}

After the call Is finished I am getting following response from this service:

    {
       "errors": [
       ],
       "info": [
       ],
       "isSuccessful": true,
       "responseHeaders": {
          "Content-Disposition": "attachment; filename=myFile.pdf",
          "Content-Length": "692204",
          "Content-Type": "application\/pdf",
          "Date": "Thu, 15 Oct 2015 15:19:56 GMT",
          "X-Powered-By": "Servlet\/3.0"
       },
       "responseTime": 11,
       "statusCode": 200,
       "statusReason": "OK",
       "text":"%PDF-1.6\n%ï¿½ï¿½ï¿½ï¿½\n159 0 obj\n<<\/Linearized 1\/L 692204\/O 162\/E 156949\/N 25\/T 691602\/H [ 531 579]>>\nendobj\n"
--long lines of characters in text field.
    }

How can I parse this response to a PDF file and show it to the user? Also I am getting this response when I right click on adapter and choose run as "call mobile adapter", when I simply call this adapter method from the application using following code:

    var invocationData = {
            adapter : "MyAdapter",
            procedure: "downloadFile",
            parameters: []
    };


    WL.Client.invokeProcedure(invocationData, {
        onSuccess: downloadFileOK, 
        onFailure: downloadFileFAIL,
        onConnectionFailure: disconnectDetect
    });

I am getting the same response on the browser's console but my "OnFailure" method "downloadFileFAIL" is getting called.

Edit Following is the log which is getting printed in Browser COnsole:

R\n>>\nstartxref\n451945\n%%EOF","errors":[],"isSuccessful":true,"statusReason":"OK","responseHeaders":{"Date":"Thu, 15 Oct 2015 21:52:40 GMT","Content-Length":"453132","Content-Disposition":"attachment; filename=myFile.pdf","Content-Type":"application\/pdf","X-Powered-By":"Servlet\/3.0"},"warnings":[],"responseTime":15,"totalTime":151,"info":[]}
worklight.js:5356 Procedure invocation error.WL.Logger.__log @ worklight.js:5356
worklight.js:5360 Uncaught Exception: Uncaught SyntaxError: Unexpected number at (compiled_code):3879WL.Logger.__log @ worklight.js:5360
worklight.js:3879 Uncaught SyntaxError: Unexpected number
worklight.js:5992 Local storage capacity reached. WL.Logger will delete old logs to make room for new ones.
worklight.js:5356 Piggybacking event transmission
worklight.js:5356 Flush called

Edit2

Following are the links to the project and its resources:

Java File
PDF File
MF Project

UPDATED:

The problem you are facing is because JS cannot handle binary data. Your best option is to base64 encode the file on your backend server and then base64 decode the file on your app before saving to a file. For Example:

Backend Server:

You will need an additional dependency in your project import org.apache.commons.codec.binary.Base64;

@POST
@Consumes(MediaType.APPLICATION_JSON)
@Produces("application/pdf")
public Response downloads() throws IOException {

    File file = new File("myFile.pdf");

    InputStream fileStream = new FileInputStream(file);

    byte[] data = new byte[1024];

    ByteArrayOutputStream buffer = new ByteArrayOutputStream();

    int read = 0;
    while ((read = fileStream.read(data, 0, data.length)) != -1) {
        buffer.write(data, 0, read);
    }

    buffer.flush();

    fileStream.close();

    ResponseBuilder response = Response.ok(Base64.encodeBase64(buffer.toByteArray()));
    response.header("Content-Disposition", "attachment; filename=myFile.pdf");
    Response responseBuilder = response.build();
    return responseBuilder;
}