Java provides two classes to implement connection-oriented communication. These are:
ServerSocket: server side of the socketSocket: client side of the socketAn object of the server socket can be made when the port number on which to bind is provided. This socket has an accept() method that blocks until a connection request is made from a client. The return value of this function is a Socket object.
The constructor takes a hostname and port number to which the request for connection is sent.
Some important methods of the Socket class are as follows:
public InputStream getInputStream() : returns the InputStream of the socketpublic OutputStream getOutputStream() : returns the OutputStream of the socketAn example of a simple TCP server-client application is given below.
class Server {public static void main( String args[] ) {ServerSocket server = new ServerSocket(8080);while (true){Socket clientSocket = server.accept();BufferedReader inFromClient = inFromClient = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));PrintWriter outToClient = new PrintWriter(clientSocket.getOutputStream(), true);String line = inFromClient.readLine();outToClient.println(line);inFromClient.close();outToClient.close();clientSocket.close();}}}
class Client {public static void main( String args[] ) {Socket socket = new Socket("hostname", 8080);PrintWriter outToServer = new PrintWriter(socket.getOutputStream(), true);BufferedReader inFromServer = new BufferedReader(new InputStreamReader(socket.getInputStream()));outToServer.println("Hello World");String echoedLine = inFromServer.readLine();inFromServer.close();outToServer.close();socket.close();}}