Java Network Tutorial - Java Network TCP Client Socket

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Socket class represents a TCP client socket.

The following code shows how to create a TCP client socket:

// Create Socket for 192.168.1.2 at  port 1234
Socket   socket = new Socket("192.168.1.2", 1234);

The following code shows how to create an unbound client socket, bind it, and connect it.

Socket socket = new Socket();
socket.bind(new InetSocketAddress("localhost",  1234));
socket.connect(new InetSocketAddress("localhost",  1234));

After connecting a Socket object, we can use its input and output streams using the getInputStream() and getOutputStream() methods, respectively.

Example

The following code shows an Echo Client Based on TCP Sockets.

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
// ww w  .  jav  a2  s . c  o  m
public class Main {
  public static void main(String[] args) throws Exception {
    Socket socket = new Socket("localhost", 12900);
    System.out.println("Started client  socket at "
        + socket.getLocalSocketAddress());
    BufferedReader socketReader = new BufferedReader(new InputStreamReader(
        socket.getInputStream()));
    BufferedWriter socketWriter = new BufferedWriter(new OutputStreamWriter(
        socket.getOutputStream()));
    BufferedReader consoleReader = new BufferedReader(
        new InputStreamReader(System.in));

    String promptMsg = "Please enter a  message  (Bye  to quit):";
    String outMsg = null;

    System.out.print(promptMsg);
    while ((outMsg = consoleReader.readLine()) != null) {
      if (outMsg.equalsIgnoreCase("bye")) {
        break;
      }
      // Add a new line to the message to the server,
      // because the server reads one line at a time.
      socketWriter.write(outMsg);
      socketWriter.write("\n");
      socketWriter.flush();

      // Read and display the message from the server
      String inMsg = socketReader.readLine();
      System.out.println("Server: " + inMsg);
      System.out.println(); // Print a blank line
      System.out.print(promptMsg);
    }
    socket.close();
  }
}

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