Question

I am using a client-server scenario. The client communicates with the server(which is a servlet) using url connection. here is the code that i am using.

 URL url = new URL("http://localhost:8080/hello");
    URLConnection connection = url.openConnection();
    connection.setDoOutput(true);
    ObjectOutputStream out=new ObjectOutputStream(connection.getOutputStream());//1st out put stream
    out.writeObject(pk);
    out.flush();
    out.close();

    ObjectInputStream in = new ObjectInputStream(connection.getInputStream());//1st instream
    PublicKey spk=(PublicKey)in.readObject();
    in.close();

    ObjectOutputStream out1=new ObjectOutputStream(connection.getOutputStream());//2nd out put stream
    out1.writeObject(str1);
    out1.flush();
    out1.close();

    ObjectInputStream in1 = new ObjectInputStream(connection.getInputStream());      
    String rstr3=(String)in1.readObject();
    //processing 
    in1.close();

But i am getting an exception called:

java.net.ProtocolException:Cannot write output after reading input. 

Where am I going wrong?

Answer 1

Instances of URLConnection are not reusable: you must use a different instance for each connection to a resource. The following code works properly(open a new urlconnection object)

URLConnection connection1 = url.openConnection();
ObjectOutputStream out1=new ObjectOutputStream(connection1.getOutputStream());//2nd out put stream
    out1.writeObject(str1);
    out1.flush();
    out1.close();

    ObjectInputStream in1 = new ObjectInputStream(connection1.getInputStream());      
    String rstr3=(String)in1.readObject();
    //processing 
    in1.close();