response.setContentType("application/pdf");
response.setHeader("Content-Disposition", "inline; filename='" + pdfName + "'");
response.setContentLength((int) FileInputStream input = new FileInputStream("File.pdf").length());

The above lines of code can be used to send a response to the view( like .jsp) as a pdf.  This will open the pdf in the browser and not make the pdf downloadable.

To indicate to the browser that the file should be viewed in the browser :

Content-Type : application/pdf

Content-Disposition : inline; filename.pdf

To have the file downloaded rather than viewed:

Content-Type : application/pdf

Content-Disposition : attachment; filename.pdf