PROBLEM while using URL in order to open a file from a servlet

Question

Hi,
I am having a problem while trying to open a file from my servlet by using URL connection. Following is my code sample. what happens is when I first run my project it opens the file but after that when I rerun it again and again it sometimes opens it and sometimes not. if it can't open it it gives an error saying "the file is damaged and couldn't be repaired". I don't get any exceptions. if you guys can help me I will appreciate it so much... thanks.
here is my code :
URL url = new URL("http://demobcs.ibm.com:81/test.pdf");
resp.setContentType(getContentType("http://demobcs.ibm.com:81/test.pdf"));
          ServletOutputStream sos = null;
          BufferedInputStream bis = null;
          try {
               sos = resp.getOutputStream();
          } catch (Exception e) {
               System.out.println("exception !!!!");
               e.printStackTrace();
          System.out.println("burada2");
          try {
               byte[] bytes = new byte[4096];
               //bis = new BufferedInputStream(conn.getInputStream());
               DataInputStream in = new DataInputStream(url.openStream());
               //DataInputStream in = new DataInputStream(conn.getInputStream());
               bis = new BufferedInputStream(in);
               int j;
               while ((j = bis.read(bytes, 0, 4096)) != -1) {
                    try {
                         sos.write(bytes, 0, 4096);
                         System.out.println("file is being read ...:");
                    } catch (Exception e) {
                         e.printStackTrace();
               in.close();
               bis.close();          
               //sos.close();
          } catch (Exception e) {
               System.out.println("exception :"+e.toString());
               e.printStackTrace();
          }

Answer 1

You are writing (<filesize> mod 4096) bytes of crap at the end of the file. Use your variable j instead for the number of bytes to write in your loop.