netty长连接实战

1，准备好netty必须的jar

<dependency>
   <groupId>io.netty</groupId>
   <artifactId>netty-all</artifactId>
   <version>4.0.23.Final</version>
</dependency>
<dependency>
   <groupId>org.msgpack</groupId>
   <artifactId>msgpack</artifactId>
   <version>0.6.12</version>
</dependency>

2，服务端-Server

启动服务方法：

public void satrtServer(int port) throws Exception {
    //处理和客户端连接的线程组（构造器参数默认是空，线程数就是当前机器CPU的内核个数）
    EventLoopGroup acceptGroup = new NioEventLoopGroup(1);
    //处理客户端与服务端写入读取的IO等业务的线程组
    EventLoopGroup handlerIoGroup = new NioEventLoopGroup(1);
    try {
        ServerBootstrap serverBootstrap = new ServerBootstrap();
                serverBootstrap.group(acceptGroup, handlerIoGroup)
                 .channel(NioServerSocketChannel.class)
                 .option(ChannelOption.SO_BACKLOG, 1024) //http缓冲区
                 .option(ChannelOption.SO_SNDBUF, 3 * 1024) //发送到客户端的最大长度
                 .option(ChannelOption.SO_RCVBUF, 3 * 1024) //接收客户端信息的最大长度
                 .option(ChannelOption.TCP_NODELAY, true)   //无延迟推送
                 .childOption(ChannelOption.SO_KEEPALIVE, true)
                 //服务端是childHandler
                 .childHandler(new ChannelInitializer<SocketChannel>() {
                     @Override
                     public void initChannel(SocketChannel ch) throws Exception {
                         ByteBuf byteBuf = Unpooled.copiedBUffer("$@$".getBytes("UTF-8"));
                         //处理客户端连续发送流导致粘包问题，客户端发送的信息需要$@$代表发生结束
                         ch.pipeline().addLast(new DelimiterBasedFrameDecoder( 3 * 1024,byteBuf));
                         ch.pipeline().addLast(new ReadTimeoutHandler(10)); //超过10秒没有读取到客户端发送的信息就关闭这个通道
                         ch.pipeline().addLast(new ServerHandler());
                     }
             });
            //异步阻塞
            ChannelFuture f = serverBootstrap.bind(port).sync();
            f.channel().closeFuture().sync();
    } finally {
            acceptGroup.shutdownGracefully();
            handlerIoGroup .shutdownGracefully();
    }
}

3，实现服务端处理业务ServerHandler：

public class ServerHandler extends ChannelInboundHandlerAdapter {
	@Override
	public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
		ByteBuf msgBuf = (ByteBuf) msg;

        String gMsg = msgBuf.toString(CharsetUtil.UTF_8);
		ctx.channel().writeAndFlush(Unpooled.copiedBuffer("收到信息了".getBytes()));
	}
	@Override
	public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
		ctx.flush();
	}
	/**
	 * 异常处理
	 */
	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
		cause.printStackTrace();
		ctx.close();
	}
}