netty实现多个handler顺序调用

在netty中，一次数据交互，可以由多个handler去处理，例如 handler1 和 handler2，那么，在前面那个handler的 messageReceived 的最后要加上 ctx.sendUpstream(e);

理论请见：

http://netty.io/3.5/api/org/jboss/netty/channel/ChannelPipeline.html

A ChannelEvent can be handled by either a ChannelUpstreamHandler or aChannelDownstreamHandler and be forwarded to the closest handler by calling ChannelHandlerContext.sendUpstream(ChannelEvent) or ChannelHandlerContext.sendDownstream(ChannelEvent).

代码：

public class Handler1 extends SimpleChannelUpstreamHandler {

    @Override

    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {

        System.out.println("1 messagereceived");

        String a = "11";

        Object o = a;

        ctx.getChannel().write(a);

        ctx.sendUpstream(e);

    }

    @Override

    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {

        e.getChannel().close();

    }

}

public class Handler2 extends SimpleChannelUpstreamHandler {

    @Override

    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {

        System.out.println("2 messagereceived");

        e.getChannel().close();

    }

    @Override

    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {

        e.getChannel().close();

    }

}

public class TcpServer {

    public static void main(String[] args) {

        System.out.println("starting a tcp server...");

        ServerBootstrap sb = new ServerBootstrap(new NioServerSocketChannelFactory(

                Executors.newCachedThreadPool(),

                Executors.newCachedThreadPool())

        );

        sb.setPipelineFactory(new PKServerPipelineFactory());

        sb.setOption("child.tcpNoDelay", true);

        sb.setOption("child.keepAlive", true);

        sb.bind(new InetSocketAddress(9999));

    }

}