Printing from applet hangs

Question

I'm trying to create an applet that can print a graphic. I have a single button and the event seems to fire when clicked. I get the security warning asking me if I want to print. I click yes and it usually pops up again and I hit yes again and then it hangs. My end goal is to print a coupon image from the browser without the print dialog so that multiple copies cannot be printed. Yes, I've heard of photo copiers but evidently the client is fine with that. At this point I'm just trying to get something to print period from the applet. Any ideas?
     public void PrintCoupon2()
          try {
          PrintRequestAttributeSet pras = new HashPrintRequestAttributeSet();
          pras.add(new Copies(1));
          PrintService pss[] = PrintServiceLookup.lookupPrintServices(DocFlavor.URL.JPEG, pras);
          if (pss.length == 0) {
               throw new RuntimeException("No printer services available.");
          PrintService ps = pss[0];
          System.out.println("Printing to " + ps);
          DocPrintJob job = ps.createPrintJob();
               URL url = new URL("http://www.mydomain.com/images/test.jpg");
               Doc doc = new SimpleDoc(url, javax.print.DocFlavor.URL.JPEG, null);
          //FileInputStream fin = new FileInputStream("IMG_0711.JPG");
          //Doc doc = new SimpleDoc(fin, DocFlavor.INPUT_STREAM.JPEG, null);
          job.print(doc, pras);
     } catch (IOException ie) {
          ie.printStackTrace();
     } catch (PrintException pe) {
          pe.printStackTrace();
     }

Answer 1

I also ran into this problem recently and I think I've figured out basically what's happening. It only happens when the applet is served by Tomcat and certain other web application servers. When the applet is launched by a simple HTML page from a web server, it is able to print without any exceptions being thrown.
In one of our applications, we have a servlet that downloads an applet to the client. When that applet calls 'PrinterJob.print', the JDK 1.4 implementation of that method on the client looks up the default 'PrintService'. To do so, it indirectly uses the class loader to get some optional configuration file (I don't know the details). That configuration file isn't in the applet's JAR file, so the class loader looks for it in the same place the JAR file came from: the server. Our servlet gets the request for the configuration file but the file isn't on the server either, so it returns a 404 error.
Here's where things go wrong. If the 404 error were sent back correctly, printing would proceed normally since the configuration file is optional. However, instead of calling 'HttpServletResponse.sendError (SC_NOT_FOUND)', the servlet calls 'HttpServletResponse.setStatus (SC_NOT_FOUND)'. I'm not sure why, but this response isn't seen by the client as a 404 error, so the body of the response is treated as the configuration file. Parsing of the body fails and the 'ServiceConfigurationError' is thrown.
We changed our servlet so that it calls 'sendError' and that fixed the 'ServiceConfigurationError' problem.
Nobody has mentioned servlets (or JSPs) being involved in their situations, but maybe there is a similar root cause. If the server is somehow not returning a 404 response, the 'PrintService' code on the client will try to parse that response and throw an error.