Writing an Asynchronous Client (Based on CompletionHandler) - Java Network

Java examples for Network:Socket Channel

  1. HOME
  2. Java
  3. Network
  4. Socket Channel

Description

Writing an Asynchronous Client (Based on CompletionHandler)

Demo Code

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.StandardSocketOptions;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.util.Random;
import java.util.concurrent.ExecutionException;

public class Main {
  public static void main(String[] args) {
    try (AsynchronousSocketChannel asyncChannel = AsynchronousSocketChannel
        .open()) {//  w  w w.j a  v  a 2 s  .co m
      if (asyncChannel.isOpen()) {
        asyncChannel.setOption(StandardSocketOptions.SO_RCVBUF, 128 * 1024);
        asyncChannel.setOption(StandardSocketOptions.SO_SNDBUF, 128 * 1024);
        asyncChannel.setOption(StandardSocketOptions.SO_KEEPALIVE, true);
        asyncChannel.connect(new InetSocketAddress("127.0.0.1", 5555), null,
            new CompletionHandler<Void, Void>() {

              ByteBuffer helloBuffer = ByteBuffer.wrap("Hello !"
                  .getBytes());
              ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
              ByteBuffer randomBuffer;
              Charset charset = Charset.defaultCharset();
              CharsetDecoder decoder = charset.newDecoder();

              @Override
              public void completed(Void result, Void attachment) {
                try {
                  System.out.println("Successfully connected at: "
                      + asyncChannel.getRemoteAddress());
                  asyncChannel.write(helloBuffer).get();
                  while (asyncChannel.read(buffer).get() != -1) {
                    buffer.flip();
                    CharBuffer charBuffer = decoder.decode(buffer);
                    System.out.println(charBuffer.toString());
                    if (buffer.hasRemaining()) {
                      buffer.compact();
                    } else {
                      buffer.clear();
                    }
                    asyncChannel.write(ByteBuffer.wrap("test".getBytes())).get();
                  }
                } catch (IOException | InterruptedException
                    | ExecutionException ex) {
                  System.err.println(ex);
                } finally {
                  try {
                    asyncChannel.close();
                  } catch (IOException ex) {
                    System.err.println(ex);
                  }
                }
              }

              @Override
              public void failed(Throwable exc, Void attachment) {
                throw new UnsupportedOperationException(
                    "Connection cannot be established!");
              }
            });
        System.in.read();
      } else {
        System.out.println("The asynchronous socket channel cannot be opened!");
      }
    } catch (IOException ex) {
      System.err.println(ex);
    }
  }
}

Result


Related Tutorials