I am trying to make a simple Client-Server application but when I execute the code I get an exception that the client cannot get the socket’s input stream.Please, take a look to my code and try to help.Thanks:)
P.S:Sorry for the messy code.Execute it as two different applications.
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.InetAddress;
import java.net.Socket;
public class SimpleClient //implements Runnable
{
private ObjectOutputStream output; // output stream to server
private ObjectInputStream input; // input stream from server
private String message = ""; // message from server
private String chatServer="localhost"; // host server for this application
private Socket client; // socket to communicate with server
public void runClient()
{
try // connect to server, get streams, process connection
{
connectToServer(); // create a Socket to make connection
getStreams(); // get the input and output streams
processConnection(); // process connection
} // end try
catch(IOException ioe)
{
ioe.printStackTrace();
}
finally
{
// closeConnection(); // close connection
} // end finally
}
private void closeConnection()
{
try
{
output.close(); // close output stream
input.close(); // close input stream
client.close(); // close socket
} // end try
catch ( IOException ioException )
{
ioException.printStackTrace();
} // end catch
} // end method closeConnection
private void connectToServer() throws IOException
{
System.out.println( "Attempting connection\n" );
// create Socket to make connection to server
client = new Socket( InetAddress.getByName( chatServer ), 12345 );
// display connection information
System.out.println( "Connected to: " +
client.getInetAddress().getHostName() );
} // end method connectToServer
private void getStreams() throws IOException
{
// set up output stream for objects
output = new ObjectOutputStream( client.getOutputStream() );
output.flush(); // flush output buffer to send header information
// set up input stream for objects
input = new ObjectInputStream( client.getInputStream() );
System.out.println( "\nGot I/O streams\n" );
} // end method getStreams
private void processConnection() throws IOException
{
do {
try // read message and display it
{
message = ( String ) input.readObject(); // read new message
System.out.println( "\n" + message ); // display message
} // end try
catch ( ClassNotFoundException classNotFoundException )
{
System.out.println( "\nUnknown object type received" );
} // end catch
} while ( !message.equals( "SERVER>>> TERMINATE" ) );
} // end method processConnection
public String toString()
{
return "client connected to "+chatServer;
}
public static void main(String []args)
{
SimpleClient c= new SimpleClient();
c.runClient();
}
}
//————-servers starts here
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
public class SimpleServer //implements Runnable
{
private ObjectOutputStream output; // output stream to client
private ObjectInputStream input; // input stream from client
private ServerSocket server; // server socket
private Socket connection; // connection to client
private int counter=1; //counts connections
ArrayList<SimpleClient> list;
/***
* Runs forever and takes care of alla
*/
public void runServer()
{
try // set up server to receive connections; process connections
{
server = new ServerSocket( 12345, 100 ); // create ServerSocket
while ( true )
{
try
{
waitForConnection(); // wait for a connection
getStreams(); // get input & output streams
processConnection(); // process connection
} // end try
catch ( Exception Exception )
{
System.out.println( "\nSomething bad happened" );
} // end catch
finally
{
closeConnection();
counter++; // close connection
} // end finally
}
}
catch ( IOException ioException )
{
System.out.println("An io error occured while creating a server-socket");
ioException.printStackTrace();
} // end catch
} // end method runServer
/***
* Waits for a client's request for connection
*/
public void waitForConnection()
{
try
{
connection = server.accept();
System.out.println("Client with IP and hostname "+connection.getInetAddress().getHostName());
} catch (IOException ex)
{
System.out.println("An error makes connection impossible");
ex.printStackTrace();
}
}
/***
* Makes the interconnection of client's and server's stream's
*/
public void getStreams()
{
try
{
output=(ObjectOutputStream) connection.getOutputStream();
input=(ObjectInputStream) connection.getInputStream();
output.flush();
System.out.println("Got IO Streams, hell yeah ");
}
catch(IOException ioe)
{
System.out.println("Cannot get streams");
ioe.printStackTrace();
}
}
/***
* Terminates connection
*/
public void closeConnection()
{
try
{
output.flush();
output.close();
input.close();
} catch (IOException ex)
{
ex.printStackTrace();
}
}
/***
* Receives messages from client
*/
public void processConnection()
{
String message="Connection successful";
do // process messages sent from client
{
try // read message and display it
{
message = ( String ) input.readObject(); // read new message
System.out.println("CLIENT>>> "+message);
} // end try
catch ( ClassNotFoundException classNotFoundException )
{
System.out.println( "\nUnknown object type received" );
}
catch(IOException ioe)
{
System.out.println("Cannot receive message from clint");
ioe.printStackTrace();
}
} while ( !message.equals( "CLIENT>>> TERMINATE" ) );
}
/***
* Sends data to client
* @param message
*/
public void sendData(String message)
{
try // send object to client
{
output.writeObject( "SERVER>>> " + message );
output.flush(); // flush output to client
System.out.println("SERVER>>> " + message);
}
catch(IOException ioe)
{
ioe.printStackTrace();
}
}
public String toString()
{
return "this is a simple server with a total of "+counter+" connections";
}
public static void main(String []args)
{
SimpleServer c= new SimpleServer();
c.runServer();
}
}
Your server is just casting the objects returned by Socket.getOutputStream() and Socket.getInputStream() to object streams. Instead, it must construct the object streams in the same way that your client does by using “new ObjectInputStream()” and “new ObjectOutputStream()”. Remember to flush the server’s ObjectOutputStream.