A Thin SMTP Client : Socket « Network « Java Tutorial

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.Socket;
import java.text.DateFormat;
import java.util.Date;
import java.util.Locale;

public class Main {
  public static void main(String[] args) throws Exception {
    String host = "host";
    int port = 25;
    String from = "from@from.net";
    String toAddr = "to@to.net";


    Socket servSocket = new Socket(host, port);
    DataOutputStream os = new DataOutputStream(servSocket.getOutputStream());
    DataInputStream is = new DataInputStream(servSocket.getInputStream());

    if (servSocket != null && os != null && is != null) {
      os.writeBytes("HELO\r\n");
      os.writeBytes("MAIL From:" + from + " \r\n");
      os.writeBytes("RCPT To:" + toAddr + "\r\n");
      os.writeBytes("DATA\r\n");
      os.writeBytes("X-Mailer: Java\r\n");
      os.writeBytes("DATE: " + DateFormat.getDateInstance(DateFormat.FULL, Locale.US).format(new Date()) + "\r\n");
      os.writeBytes("From:" + from + "\r\n");
      os.writeBytes("To:" + toAddr + "\r\n");
    }

    os.writeBytes("Subject:\r\n");
    os.writeBytes("body\r\n");
    os.writeBytes("\r\n.\r\n");
    os.writeBytes("QUIT\r\n");
    String responseline;
    while ((responseline = is.readUTF()) != null) { 
      if (responseline.indexOf("Ok") != -1)
        break;
    }
  }
}

19.9.Socket
	19.9.1.	java.net.Socket
	19.9.2.	Create a socket
	19.9.3.	Create Socket by IP address and port number
	19.9.4.	Display Socket InetAddress, Port, LocalPort and Local address
	19.9.5.	Socket Info
	19.9.6.	Get InputStream and OutputStream from Socket
	19.9.7.	Read float number from a Socket
	19.9.8.	Read Object from Socket
	19.9.9.	A Thin SMTP Client
	19.9.10.	Get internet address from connected socket client
	19.9.11.	Transfer a file via Socket
	19.9.12.	Cipher Socket