我用netty編寫了一個應用程序，將消息從客戶端發送到服務器，但是服務器無法接收消息

Question

我用netty編寫了一個應用程序，客戶端使用channelActive方法將字符串消息發送到服務器，但是服務器未收到該消息。 我不知道原因。

服務器代碼：

public static void main(String[] args) throws InterruptedException {
    NioEventLoopGroup boss = new NioEventLoopGroup();
    NioEventLoopGroup worker = new NioEventLoopGroup();
    try {
        ServerBootstrap bootstrap = new ServerBootstrap();

        bootstrap.group(boss,worker);
        bootstrap.channel(NioServerSocketChannel.class);
        bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
                ch.pipeline().addLast(new NettyServerHandler());
            }
        });
        bootstrap.option(ChannelOption.SO_BACKLOG,1024);
        bootstrap.childOption(ChannelOption.SO_KEEPALIVE,true);

        ChannelFuture sync = bootstrap.bind(8080).sync();

        System.out.println("server start");

        sync.channel().closeFuture().sync();

        System.out.println("server end");
    } finally {
        worker.shutdownGracefully();
        boss.shutdownGracefully();
    }
}

public class NettyServerHandler extends ChannelInboundHandlerAdapter {

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    System.out.println("channelRead");

    super.channelRead(ctx, msg);
    System.out.println(((ByteBuf) msg).toString(Charset.defaultCharset()));

}

@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
    System.out.println("channelActive");
    super.channelActive(ctx);
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    System.out.println("exceptionCaught");
    super.exceptionCaught(ctx, cause);

    cause.printStackTrace();
    ctx.close();
}
}

我在服務器處理程序的方法channelRead中從客戶端打印消息。

以下是客戶端代碼：

public static void main(String[] args) throws InterruptedException {
    NioEventLoopGroup worker = new NioEventLoopGroup();
    try {
        Bootstrap bootstrap = new Bootstrap();

        bootstrap.group(worker);
        bootstrap.channel(NioSocketChannel.class);
        bootstrap.handler(new ChannelInitializer<Channel>() {
            @Override
            protected void initChannel(Channel ch) throws Exception {
                ch.pipeline().addLast(new NettyClientHandler());
            }
        });

        ChannelFuture future = bootstrap.connect("localhost", 8080).sync();

        future.channel().closeFuture().sync();
    }finally {
        worker.shutdownGracefully();
    }
}

public class NettyClientHandler extends ChannelInboundHandlerAdapter {

@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
    System.out.println("channelActive");
    super.channelActive(ctx);
    ctx.writeAndFlush("message from client");
}

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    System.out.println("channelRead");
    super.channelRead(ctx, msg);

}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    System.out.println("exceptionCaught");
    super.exceptionCaught(ctx, cause);

    cause.printStackTrace();
    ctx.close();

}
}

我從通道處於活動狀態的客戶端發送了消息，但服務器未收到消息，字符串“來自客戶端的消息”

Answer 1

那是因為您在調用writeAndFlush(...)時使用了String 。 返回的ChannelFuture應該告訴您不支持的消息類型。 如果要使用String ，則需要將StringEncoder放在ChannelPipeline ，否則僅需要編寫ByteBuf實例。