This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I am developing an application that uses an applet for the user interface and a servlet for data retrieval. I am having an issue getting the data from the Servlet back to the applet. My control flow is below:
1. The applet creates an serialized object that is sent to the servlet using the ObjectOutputStream. - This works fine.
2. The servlet receives the object via the ObjectInputStream and pulls date from the object to create a database query. - Also works fine.
3. Using the data from the query, the servlet builds a serialized object that it sends back to the Servlet via the ObjectOutputStream. - Seems to work.
4. The applet then reads the object sent via the ObjectInputStream, but the object is empty.
Just before sending the object from the servlet back to the applet, I print out the objects get methods and the data is in the object.
I do the same when the applet recieves the object from the servlet, but there is no data.
This is the code I am using to return the object (myPlayer) from the Communicator servlet to the applet:
System.out.println("Communicator ==>> getArmorClass = " + myPlayer.getArmorClass()); - The data displayed is correct.
System.out.println("Communicator ==>> getCharName = " + myPlayer.getCharName()); - The data displayed is correct.
res.setContentType("java-internal/" + Player.class.getName());
OutputStream out = res.getOutputStream();
System.out.println("Applet Main getArmorClass = " + myPlayer.getArmorClass());
System.out.println("Applet Main getCharName = " + myPlayer.getCharName());
Not sure what I am doing wrong here, it seems strange that I can send a serialized object from the applet to the servlet, do my database work and build a new serialized object, but when I pass it back to the applet there is no data in it. Any suggestions would be greatly appreciated.
Not sure what the problem is, but be aware that object serialization between different JVMs can easily break if the two JVMs are not the exact same version. Unless you can guarantee that, you may be better off using the java.beans.XMLEncoder/XMLDecoder classes.