第二课 Netty服务端

netty应用的领域

1分布式进程通信
例如: hadoop、dubbo、akka等具有分布式功能的框架，底层RPC通信都是基于netty实现的，这些框架使用的版本通常都还在用netty3.x

2、游戏服务器开发
最新的游戏服务器有部分公司可能已经开始采用netty4.x 或 netty5.x

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代码示例

public class Server {    public static void main(String[] args) {        ServerBootstrap serverBootstrap = new ServerBootstrap();        ExecutorService boss = Executors.newCachedThreadPool();        ExecutorService worker = Executors.newCachedThreadPool();        //设置NioSocket工厂        serverBootstrap.setFactory(new NioServerSocketChannelFactory(boss,worker));        //设置管道工厂        serverBootstrap.setPipelineFactory(new ChannelPipelineFactory() {            @Override            public ChannelPipeline getPipeline() throws Exception {                //创建管道                ChannelPipeline pipeline = Channels.pipeline();                pipeline.addLast("decoder", new StringDecoder());                pipeline.addLast("encoder", new StringEncoder());                pipeline.addLast("ServerHandler", new ServerHandler());                return pipeline;            }        });        serverBootstrap.bind(new InetSocketAddress(8000));        System.out.println("NIOServer started!!!!!!!!!!!");    }}

public class ServerHandler extends SimpleChannelHandler{    @Override    public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e)            throws Exception {        System.out.println("channelClosed");        super.channelClosed(ctx, e);    }    @Override    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent event)            throws Exception {        System.out.println("channelConnected"+event.getChannel().getRemoteAddress());        super.channelConnected(ctx, event);    }    @Override    public void channelDisconnected(ChannelHandlerContext ctx,            ChannelStateEvent e) throws Exception {        System.out.println("channelDisconnected");        super.channelDisconnected(ctx, e);    }    @Override    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)            throws Exception {        System.out.println("exceptionCaught");        super.exceptionCaught(ctx, e);    }    @Override    public void messageReceived(ChannelHandlerContext context, MessageEvent message)            throws Exception {        String buffer = (String) message.getMessage();        System.out.println("received message:"+buffer);        ChannelBuffer buffer2 = ChannelBuffers.copiedBuffer("Hi".getBytes());        context.getChannel().write(buffer2);        super.messageReceived(context, message);    }}