When using URLConnection read input stream error

Question

hi,
In my applet I build a URLConnection, it connect a jsp file. In my jsp file I refer to a javaBean. I send two objects of request and response in jsp to javaBean. In javabean return output stream to URLConnect. At that time a error happened.WHY???(Applet-JSP-JAVABean)
Thanks.
My main code:
APPLET:(TestApplet)
URL url = new URL("http://210.0.8.120/jsp/test.jsp";
URLConnection con;
con = url .openConnection();
con = servlet.openConnection();
con.setDoInput( true );
con.setDoOutput( true );
con.setUseCaches( false );
con.setRequestProperty( "Content-Type","text/plain" );
con.setAllowUserInteraction(false);
ObjectOutputStream out;
out = new ObjectOutputStream(con.getOutputStream());
Serializable[] data ={"test"};
out.writeObject( data );
out.flush();
out.close();
//until here are all rigth
ObjectInputStream in = new ObjectInputStream( con.getInputStream() );//happened error
JSP:
TestBean testBean = new TestBean ();
testBean .execute(request, response);
JAVABEAN:
public void execute( HttpServletRequest request,
HttpServletResponse response )
ObjectInputStream in = new ObjectInputStream( request.getInputStream() );
String direct = (String) in.readObject();
System.out.prinltn("direct");
ObjectOutputStream out = new ObjectOutputStream( response.getOutputStream() );
SerializableSerializable[] data ={"answer"};
out.writeObject( data );
out.flush();
out.close();
Error detail:
java.io.StreamCorruptedException: invalid stream header
     at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:729)
     at java.io.ObjectInputStream.<init>(ObjectInputStream.java:251)
     at TestApplet.postObjects(TestApplet.java:172)

Answer 1

you have to pay attention to the sequence of opening the streams.
The following example is: client sends a string to server, and servlet sends a response string back.
client side:
         URL url = new URL( "http://152.8.113.149:8080/conn/servlet/test" );
         URLConnection conn = url.openConnection();   
         System.out.println( "conn: " + conn );
         conn.setDoOutput( true );
         conn.setDoInput( true );
         conn.setUseCaches( false );
         conn.setDefaultUseCaches (false);
         // send out a string
         OutputStream out = conn.getOutputStream();
         ObjectOutputStream oOut = new ObjectOutputStream( out );
         oOut.writeObject( strSrc ); 
         // receive a string
         InputStream in = conn.getInputStream();     
         ObjectInputStream oIn = new ObjectInputStream( in );
         String strDes = (String)oIn.readObject();server side
         // open output stream
         OutputStream out = res.getOutputStream();  
         ObjectOutputStream oOut = new ObjectOutputStream( out );
         // open input stream and read from client
         InputStream in  = req.getInputStream();
         ObjectInputStream oIn = new ObjectInputStream( in );
         String s = (String)oIn.readObject();
         System.out.println( s );
         // write to client
         oOut.writeObject( s + " back" ); I have the complete example at http://152.8.113.149/samples/app_servlet.html
don't forget to give me the duke dollars.