添加解码器/编码器时网络管线中断

Question

我最近开始将netty用于我的一个项目。 为了了解netty的工作原理，我实现了HexDumpProxy示例。 我在通道管道中添加StringDecoder和StringEncoder时遇到问题，这会导致管道中断。 如果不存在解码器/编码器，则程序将正常运行。 有人可以解释一下为什么会这样吗？ 任何帮助深表感谢！

接下来，我要添加代码。

主班：

public final class HexDumpProxy {

public static void main(String[] args) throws Exception {

    // Configure the bootstrap.
    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 HexDumpProxyInitializer("127.0.0.1", 9000))
         .childOption(ChannelOption.AUTO_READ, false)
         .bind(8000).sync().channel().closeFuture().sync();
    } finally {
        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();
        }
    }
}

初始化类：

public class HexDumpProxyInitializer extends ChannelInitializer<SocketChannel> {

private final String remoteHost;
private final int remotePort;

public HexDumpProxyInitializer (String remoteHost, int remotePort) {
    this.remoteHost = remoteHost;
    this.remotePort = remotePort;
}

@Override
protected void initChannel(SocketChannel ch) throws Exception {
    ch.pipeline().addLast("frameDecoder", new LineBasedFrameDecoder(80));
    ch.pipeline().addLast("decoder", new StringDecoder());
    ch.pipeline().addLast("encoder", new StringEncoder());
    //ch.pipeline().addLast(new LoggingHandler(LogLevel.INFO));
    ch.pipeline().addLast(new HexDumpProxyFrontendHandler(remoteHost, remotePort));
    }

}

前端处理程序类：

public class HexDumpProxyFrontendHandler extends ChannelInboundHandlerAdapter {

private final String remoteHost;
private final int remotePort;

private Channel serverChannel;

public HexDumpProxyFrontendHandler(String remoteHost, int remotePort) {
    this.remoteHost = remoteHost;
    this.remotePort = remotePort;
}

@Override
public void channelActive(ChannelHandlerContext ctx) {
    final Channel clientChannel = ctx.channel();

    Bootstrap b = new Bootstrap();
    b.group(clientChannel.eventLoop())
     .channel(ctx.channel().getClass())
     .handler(new HexDumpProxyBackendHandler(clientChannel))
     .option(ChannelOption.AUTO_READ, false);

    ChannelFuture f = b.connect(remoteHost, remotePort);
    serverChannel = f.channel();
    f.addListener(new ChannelFutureListener() {
        public void operationComplete(ChannelFuture future) {
            if (future.isSuccess()) {
                clientChannel.read();
            }
            else
                clientChannel.close();
            }

        });
}

@Override
public void channelRead (final ChannelHandlerContext ctx, Object msg) {
    if (serverChannel.isActive()) {
        System.out.println("************" + msg);
        serverChannel.writeAndFlush(msg).addListener(new ChannelFutureListener() {
            public void operationComplete(ChannelFuture future) {
                if (future.isSuccess()) {
                    ctx.channel().read();
                    System.out.println("Read from server channel. - channelRead");
                } else {
                    future.channel().close();
                    System.out.println("Close server channel.");
                }
            }
        });
    }
}

@Override
public void channelInactive (ChannelHandlerContext ctx) {
    if (serverChannel != null) {
        closeOnFlush(serverChannel);
        System.out.println("close on flush - server channel");
    }
}

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

static void closeOnFlush (Channel ch) {
    if (ch.isActive())
        ch.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
}

@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
    ctx.flush();
    ctx.channel().read();
    }
}

后端处理程序类：

public class HexDumpProxyBackendHandler extends ChannelInboundHandlerAdapter {

private final Channel clientChannel;

public HexDumpProxyBackendHandler (Channel clientChannel) {
    this.clientChannel = clientChannel;
}

@Override
public void channelActive (ChannelHandlerContext ctx) {
    ctx.channel().read();
    System.out.println("Read from client channel. - channelActive");
}

@Override
public void channelRead (final ChannelHandlerContext ctx, Object msg) {
    System.out.println("~~~~~~~~~~~" + msg);
    clientChannel.writeAndFlush(msg).addListener(new ChannelFutureListener() {
        public void operationComplete(ChannelFuture future) {
            if (future.isSuccess()) {
                clientChannel.read();
                System.out.println("Read from client channel. - channelRead");
            } else {
                clientChannel.close();
                System.out.println("Close client channel.");
                }
            }
        });
}

@Override
public void channelInactive (ChannelHandlerContext ctx) {
    HexDumpProxyFrontendHandler.closeOnFlush(clientChannel);
    System.out.println("close on flush - client channel");
}

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

@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
    ctx.flush();
    ctx.channel().read();
    }
}

Answer 1

对于将来会遇到类似问题的每个人，我都知道问题出在哪里。

在类HexDumpProxyFrontendHandler而不是在引导过程中使用新的HexDumpProxyBackendHandler(clientChannel)作为处理程序，创建一个新类，例如HexDumpProxyBackendInitializer(clientChannel)并在该类中以与类HexDumpProxyInitializer相同的方式初始化管道。

希望这可以帮助某人！