Using ChannelGroup to close all connected channel

Handler.java

@Override
public void channelConnected(ChannelHandlerContext ctx,
		ChannelStateEvent e) throws Exception {
	this.channel = e.getChannel();
	channels.add(channel);
}

Server.java

private Channel channel;
private ChannelGroup channels;

public void start() {
	this.channel = bootstrap.bind(localAddress);
	this.channels = new DefaultChannelGroup();
	channels.add(channel);
}

public void stop() {
	channels.close().awaitUninterruptibly();
	bootstrap.releaseExternalResources();
}