IdleStateHandlerInitializer.java

package com.manning.nettyinaction.chapter8;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.timeout.IdleStateEvent;
import io.netty.handler.timeout.IdleStateHandler;
import io.netty.util.CharsetUtil;

import java.util.concurrent.TimeUnit;

/**
 * @author <a href="mailto:norman.maurer@googlemail.com">Norman Maurer</a>
 */
public class IdleStateHandlerInitializer extends ChannelInitializer<Channel> {

    @Override
    protected void initChannel(Channel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        pipeline.addLast(new IdleStateHandler(0, 0, 60, TimeUnit.SECONDS));
        pipeline.addLast(new HeartbeatHandler());
    }

    public static final class HeartbeatHandler extends ChannelInboundHandlerAdapter {
        private static final ByteBuf HEARTBEAT_SEQUENCE = Unpooled.unreleasableBuffer(
                Unpooled.copiedBuffer("HEARTBEAT", CharsetUtil.ISO_8859_1));

        @Override
        public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
            if (evt instanceof IdleStateEvent) {
                 ctx.writeAndFlush(HEARTBEAT_SEQUENCE.duplicate())
                         .addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
            } else {
                super.userEventTriggered(ctx, evt);
            }
        }
    }
}