未调用Netty处理程序

Question

我试图使用一个简单的服务器-客户端应用程序（代码见下文）进入Netty。

我在与两个问题作斗争：

null

KJ

这就是服务器的创建方式：

public void run() throws Exception {

    EventLoopGroup bossGroup = new NioEventLoopGroup(1);
    EventLoopGroup workerGroup = new NioEventLoopGroup();
    try {
        ServerBootstrap b = new ServerBootstrap();
        b.group(bossGroup, workerGroup)
         .channel(NioServerSocketChannel.class)
         .handler(new LoggingHandler(LogLevel.INFO))
         .childHandler(new ChannelInitializer<SocketChannel>() {
             @Override
             public void initChannel(SocketChannel ch) throws Exception {
                 ChannelPipeline p = ch.pipeline();
                 p.addLast(
                     new ObjectEncoder(),
                     new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
                     new ConfigServerHandler(),
                     new FeedbackServerHandler());
             }
         });
      b.bind(mPort).sync().channel().closeFuture().sync();
    } finally {
        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();
    }
}

其中一个处理程序类（FeedbackServerHandler执行完全相同的操作，但解析为整数）：

public class ConfigServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        System.out.println("ConfigServerHandler::channelRead, " +(String)msg);
        ctx.write(msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
   }
}

public Client(String host, int port) throws InterruptedException {

    EventLoopGroup workerGroup = new NioEventLoopGroup();
    try {
        Bootstrap b = new Bootstrap();
        b.group(workerGroup)
         .channel(NioSocketChannel.class)
         .handler(new ChannelInitializer<SocketChannel>() {
             @Override
             public void initChannel(SocketChannel ch) throws Exception {
                 ChannelPipeline p = ch.pipeline();
                  p.addLast(
                      new ObjectEncoder(),
                      new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
                      new ConfigClientHandler(),
                      new FeedbackClientHandler());
             }
         });
         b.connect(host, port).sync().channel().closeFuture().sync();
    } finally {
        workerGroup.shutdownGracefully();
    }
}

public class ConfigClientHandler extends ChannelInboundHandlerAdapter {

    private final String firstMessage = "blubber";

    @Override
    public void channelActive(ChannelHandlerContext ctx) {
        System.out.println("ConfigClientHandler::channelActive");
        ctx.writeAndFlush(firstMessage);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        System.out.println("ConfigClientHandler::channelRead, " +(String)msg);
        ctx.write(msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

Answer 1

您将ChannelInboundHandlerAdapter用于“中间”处理程序ConfigxxxxHandler。

但是您使用channelread方法，然后使用insidectx.write(msg)。ctx.write(msg)将首先通过前一个处理程序(ObjectDecoder)将msg写回另一个服务器，而不是下一个处理程序(FeedbackClientHandler)。

如果要将消息发送到下一个处理程序，则应使用以下方法：

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
    System.out.println("ConfigClientHandler::channelRead, " +(String)msg);
    ctx.fireChannelRead(msg);
}

当然，在ChannelReadComplete中没有ctx.flush()（因为没有更多的内容）。但是在最后的FeedbackClientHandler中，当然要使用flush方法和ctx.write(yourNewMessage)或使用ctx.writeandflush(yourNewMessage)。

所以继续说：

null

您也许还应该倒置编码器/解码器，因为一般来说，在管道中首先有解码器，然后有编码器是个好主意。

            p.addLast(
                      new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
                      new ObjectEncoder(),
                      new ConfigClientHandler(),
                      new FeedbackClientHandler());