I am writing an application where a user can download files. These files can be of type pdf, doc, xls, csv or ppt. The jsp which has the links to the files calls a DownloadServlet which fetches the file and writes it to the outout stream. These files are not located under the WEB-INF folder but on another directory (eg. C:\downloads).
When the user clicks on the link, it pops up a box which asks if they want to Save or Open the file. All files work fine when they are downloaded. When user tries to open a pdf file, it opens up Adobe Reader but then gives an error message-
"There was an error opening this document. This file cannot be found."
The doc & xls files open up fine.

Here is the code to my download servlet -

public class DownloadServlet extends HttpServlet {
    
    //Initialize global variables
    String fileName="";
    
    private static Logger log = Logger.getLogger(DownloadServlet.class.getName());
    
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
    }
    
    //Process the HTTP Get request
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
            IOException {
        doPost(request,response);
    }
    
    //Process the HTTP Post request
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        log.debug("Entered DownloadServlet");
        OutputStream outStream = response.getOutputStream();
        fileName=request.getParameter("fileName");
        log.debug("Filename:"+fileName);
        String filePath = "C:\\test
reference-material";
        File f=new File(filePath, fileName);
        String fileType = fileName.substring(fileName.indexOf(".")+1,fileName.length());
        log.debug("Filetype:"+fileType+";"+f.length());

        if (fileType.trim().equalsIgnoreCase("txt")) {
            response.setContentType( "text/plain" );
        } else if (fileType.trim().equalsIgnoreCase("doc")) {
            response.setContentType( "application/msword" );
        } else if (fileType.trim().equalsIgnoreCase("xls")) {
            response.setContentType( "application/vnd.ms-excel" );
        } else if (fileType.trim().equalsIgnoreCase("pdf")) {
            response.setContentType( "application/pdf" );
            log.debug("content type set to pdf");
        } else {
            response.setContentType( "application/octet-stream" );
        }

        response.setContentLength((int)f.length());
         response.setHeader("Content-Disposition","attachment; filename=\"SecurityPatterns.pdf\"");

        response.setHeader("Cache-Control", "no-cache");
        byte[] buf = new byte[8192];
        FileInputStream inStream = new FileInputStream(f);
        int sizeRead = 0;
        while ((sizeRead = inStream.read(buf, 0, buf.length)) > 0) {
            log.debug("size:"+sizeRead);
            outStream.write(buf, 0, sizeRead);
        }
        inStream.close();
        outStream.close();
        
    }
    
    //Get Servlet information
    public String getServletInfo() {
        return "DownloadServlet Information";
    }
}

Check out Download servlet in JSOS:
http://www.servletsuite.com/servlets.htm

Thanks, that works great.
Although, I am curious to find out what I was doing wrong.

The following fixed the problem for me. response.setHeader("Cache-Control", "max-age=60"); Another possible solution is to change the content type from "application/pdf" to "application/octet-stream".