Streaming files through servlet

Question

Hi,
I'm trying to stream a file to the client browser via a Struts action. I use a helper method as follows:
public static void streamFile(HttpServletResponse response, String contentType, String fileName, InputStream fileData) throws Exception {
          response.setContentType(contentType);
          response.setHeader("Content-disposition", "attachment; filename=" + fileName);
          BufferedInputStream bis = null;
          BufferedOutputStream bos = null;
          OutputStream out = response.getOutputStream();
          try {     
               bis = new BufferedInputStream(fileData);
               bos = new BufferedOutputStream(out);
               byte[] buff = new byte[2048];
               int bytesRead;
               //     Simple read/write loop.
               while(-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
                    bos.write(buff, 0, bytesRead);
          } catch (Exception e) {
               throw new Exception("Could not stream file. Error: " + e.getMessage());
          } finally {
               if (bis != null) {
                    bis.close();
               if (bos != null) {
                    bos.close();
     }Here's the execute method code for my download action:
InputStream is = new FileInputStream(new File("g:/Test.txt"));
          FileHelper.streamFile(response, "text/plain", "Test.txt", is);
          return null; "G:\Test.txt" is a valid file. When I tried to run the code, I got this error from the client:
Internet Exporer cannot download download.do from 127.0.0.1. Internet Explorer was not able to open this site.
The requested site is either unavailable or cannot be found. Please try again later.
Any ideas what I'm missing here?
Thanks in advance for any suggestions!

Answer 1

Hi all,
Have found out what's wrong with this.
Seems like the struts contoller was set to use nocache="true" option, which causes problems because in order for files to be downloaded onto the client, caching must be enabled.
This applies for all web application processes which need to download files onto the client.
E.g., if you are using servlets/JSP, you need to make sure that you do not send the pragma=no-cache header.
E.g. if you use a framework like Struts, you need to make sure that the framework does not disable caching for the module which handles the download.