DeregisterChannel.java

package com.manning.nettyinaction.chapter16;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.net.InetSocketAddress;

/**
 * @author <a href="mailto:nmaurer@redhat.com">Norman Maurer</a>
 */
public class DeregisterChannel {

    public void deregister() {
        EventLoopGroup group = new NioEventLoopGroup();
        Bootstrap bootstrap = new Bootstrap();
        bootstrap.group(group).channel(NioSocketChannel.class)
                .handler(new SimpleChannelInboundHandler<ByteBuf>() {
                    @Override
                    protected void channelRead0(ChannelHandlerContext ctx, ByteBuf byteBuf) throws Exception {
                        ctx.deregister();
                    }
                });
        ChannelFuture future = bootstrap.connect(new InetSocketAddress("www.manning.com", 80));
        future.addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture channelFuture) throws Exception {
                if (channelFuture.isSuccess()) {
                    System.out.println("Connection established");
                } else {
                    System.err.println("Connection attempt failed");
                    channelFuture.cause().printStackTrace();
                }
            }
        });

        // Do something which takes some amount of time

        // Register channel again on eventloop
        Channel channel = future.channel();
        group.register(channel).addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                if (future.isSuccess()) {
                    System.out.println("Channel registered");
                } else {
                    System.err.println("Register Channel on EventLoop failed");
                    future.cause().printStackTrace();
                }
            }
        });
    }
}