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I have an applet trying to send java serialized object to a servlet (hosted in Tomcat 6). The URLs are correct and the applet reaches the correct servlet, but when it comes to reading anything on the servlet side, I get an error.

Here is the applet code :


String adresse = "/Applic_ClientsPartners/NewMemberServlet";
URL page = getDocumentBase();
String protocole = page.getProtocol();
String host = page.getHost();
int port = page.getPort();
System.out.println(protocole + "://" + host + ":" + port + adresse);
URL serv = new URL(protocole, host, port, adresse);
URLConnection conn = serv.openConnection();
conn.setUseCaches(false);
conn.setDefaultUseCaches(false);
//conn.setRequestProperty("Content-Type", "application/x-java-serialized-object");
conn.setRequestProperty("Content-Type", "application/octet-stream");
conn.setDoInput(true);
conn.setDoOutput(true);
System.out.println("Connection open");
ObjectOutputStream oos = new ObjectOutputStream(conn.getOutputStream());
ObjectInputStream ois = new ObjectInputStream(conn.getInputStream());
System.out.println("Envoi de 'test'"); //sending a test String
String t = "test";
oos.writeObject(t);
System.out.println("test flush");
oos.flush();
System.out.println("test between flush & writeObject");
oos.writeObject(nouveau); //this is a serializable custom object
oos.flush();
//Boolean result = ois.readBoolean();
ois.close();
oos.close();
System.out.println("Streams fermés"); //streams closed successfully

Here is the servlet code :


response.setContentType("application/octet-stream");
ObjectInputStream ois = new ObjectInputStream(request.getInputStream());
ObjectOutputStream oos = new ObjectOutputStream(response.getOutputStream());
System.out.println("AVAILABLE " + ois.available());
System.out.println("Pré read test");
String t = (String) ois.readObject();
System.out.println(t + " lu");
Cards.Member nouveau = (Cards.Member) ois.readObject();
System.out.println("Post read test");
oos.close();
ois.close();
System.out.println("Streams fermés"); //Streams closed successfully
return;

I have a try ... catch(IOException ex) surrounding both of course. The error is the following : 


java.io.EOFException
        at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2554)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351)
        at Servlets.NewMemberServlet.doPost(NewMemberServlet.java:96)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
        at java.lang.Thread.run(Thread.java:619)

I really don't understand what's happening here : The servlet's ObjectInputStream seems to get nothing, but I have another applet-servlet in the same web project, albeit with an http tunnel, and they're working perfectly?!

Any help would be greatly appreciated :)

Lupuss
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  • There are two calls to .readObject(), which is the one raising the exception? – vz0 Jan 27 '11 at 14:15
  • And what are the test outputs that you see on standard out? – biziclop Jan 27 '11 at 14:23
  • The first call to readObject() throws the Exception; as for the test outputs, all of them are displayed for the applet, but the servlet stops at "Pré read test" (so just before the first call to readObject()). Hope this helps. – Lupuss Jan 27 '11 at 14:41

2 Answers2

1

Try creating the ObjectInputStream in your applet only after you have written data to the ObjectOutputStream. And on servlet side, delay creation of the ObjectOutputStream.

Reasons:

I think the code as you have written it should work (it's in correct sequence), but I know I've had issues around sequence and timing of these stream setups in the past.

kaliatech
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  • It worked! Thanks for your helps and the useful links. The objects are now sent and read correctly. – Lupuss Jan 27 '11 at 15:00
1

On your servlet, do all input processing first, and only then deal with the output processing. In particular, I'd reorder your code as:

// Read input:
ObjectInputStream ois = new ObjectInputStream(request.getInputStream());
System.out.println("AVAILABLE " + ois.available());
System.out.println("Pré read test");
String t = (String) ois.readObject();
System.out.println(t + " lu");
Cards.Member nouveau = (Cards.Member) ois.readObject();
System.out.println("Post read test");
ois.close();

// Write output:
response.setContentType("application/octet-stream");
ObjectOutputStream oos = new ObjectOutputStream(response.getOutputStream());
// oos.writeObject(someSerializablebject);
oos.close();
System.out.println("Streams fermés"); //Streams closed successfully
Dov Wasserman
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