Java examples for Network:UDP
Writing a Connected UDP Client
import java.io.IOException; import java.net.InetSocketAddress; import java.net.StandardProtocolFamily; import java.net.StandardSocketOptions; import java.nio.ByteBuffer; import java.nio.CharBuffer; import java.nio.channels.ClosedChannelException; import java.nio.channels.DatagramChannel; import java.nio.charset.Charset; import java.nio.charset.CharsetDecoder; public class Main { public static void main(String[] args) throws IOException { CharBuffer charBuffer = null; Charset charset = Charset.defaultCharset(); CharsetDecoder decoder = charset.newDecoder(); ByteBuffer textToEcho = ByteBuffer.wrap("server!".getBytes()); ByteBuffer echoedText = ByteBuffer.allocateDirect(65507); try (DatagramChannel datagramChannel = DatagramChannel .open(StandardProtocolFamily.INET)) { datagramChannel.setOption(StandardSocketOptions.SO_RCVBUF, 4 * 1024); datagramChannel.setOption(StandardSocketOptions.SO_SNDBUF, 4 * 1024); if (datagramChannel.isOpen()) { datagramChannel.connect(new InetSocketAddress("127.0.0.1", 5555)); if (datagramChannel.isConnected()) { int sent = datagramChannel.write(textToEcho); System.out.println("I have successfully sent " + sent + " bytes to the Echo Server!"); datagramChannel.read(echoedText); echoedText.flip();//from ww w. ja va 2s . c o m charBuffer = decoder.decode(echoedText); System.out.println(charBuffer.toString()); echoedText.clear(); } else { System.out.println("The channel cannot be connected!"); } } else { System.out.println("The channel cannot be opened!"); } } catch (Exception ex) { if (ex instanceof ClosedChannelException) { System.err.println("The channel was unexpected closed ..."); } if (ex instanceof SecurityException) { System.err.println("A security exception occured ..."); } if (ex instanceof IOException) { System.err.println("An I/O error occured ..."); } ex.printStackTrace(); } } }