Goal

• Java NIO DatagramChannel을 이용하여 UDP Send/Receive 구현

Practice

DatgramChannel Receiver

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/** ***************************************************************** * * NIOUDPRecvTest.java * * NIO DatagramChannel Receiver * ***************************************************************** * * @version 1.0.0 2017-10-11 dorbae 최초생성 * @since 1.0.0 * @author dorbae * */ package test; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.DatagramChannel; public class NIOUDPRecvTest { /** * * @version 1.0.0 2017-10-11 dorbae 최초생성 * @since 1.0.0 * @author dorbae * * @param args */ public static void main(String[] args) { DatagramChannel channel = null; try { channel = DatagramChannel.open(); channel.socket().bind(new InetSocketAddress("localhost", 9000)); } catch (IOException e) { e.printStackTrace(); System.exit(1); } ByteBuffer buf = ByteBuffer.allocate(256); byte[] buffer = new byte[256]; int limit = 0; try { while (true) { buf.clear(); try { System.out.println("\nWaiting..."); channel.receive(buf); limit = buf.limit(); System.out.println("buf.limit()=" + limit); System.out.println("buf.capacity()=" + buf.capacity()); System.out.println("buf.position()=" + buf.position()); System.out.println("buf.arrayOffset()=" + buf.arrayOffset()); buf.flip(); limit = buf.limit(); System.out.println("buf.limit()=" + limit); buf.get(buffer, 0, limit); System.out.println("data=" + new String(buffer, 0, limit, "utf8")); } catch (IOException e) { break; } } } catch (Exception e) { e.printStackTrace(); } finally { if (channel != null) try { channel.close(); } catch (IOException e) {} } } }

DatagramChannel Sender

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/** ***************************************************************** * * NIOUDPSendTest.java * * NIO DatagramChannel Sender * ***************************************************************** * * @version 1.0.0 2017-10-11 dorbae 최초생성 * @since 1.0.0 * @author dorbae * */ package test; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.DatagramChannel; public class NIOUDPSendTest { /** * * @version 1.0.0 2017-10-11 dorbae 최초생성 * @since 1.0.0 * @author dorbae * * @param args * @throws IOException */ public static void main(String[] args) throws IOException { String message = "한글 String to write to file..." + System.currentTimeMillis(); DatagramChannel channel = DatagramChannel.open(); ByteBuffer buf = ByteBuffer.allocate(256); buf.clear(); buf.put(message.getBytes("utf8")); buf.flip(); int bytesSent = channel.send(buf, new InetSocketAddress("localhost", 9000)); } }