java - 在 Netty 中关闭客户端连接

Question

我有简单的 Netty 客户端/服务器应用程序。在服务器端，我检查客户端是否从正确的主机连接，如果不正确，则关闭客户端的连接。在服务器端我使用这段代码:

@Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {

        String remoteAddress = ctx.channel().remoteAddress().toString();
        if(!"/127.0.0.1:42477".equals(remoteAddress)) {
            ctx.writeAndFlush("Not correct remote address! Connection closed");
            ctx.close();
        }
        System.out.println(remoteAddress);
    }

在客户端这一个:

@Override
    protected void channelRead0(ChannelHandlerContext ctx, String data) throws Exception {
        try {
            System.err.println(data);
        } finally {
            ReferenceCountUtil.retain(data);
        }       
    }

但我无法在 ctx.writeAndFlush() 中从服务器端获取消息并且客户端异常关闭:

java.io.IOException: Соединение сброшено другой стороной(TRANSLATION: Connection reset from the other side)
    at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
    at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
    at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
    at sun.nio.ch.IOUtil.read(IOUtil.java:192)
    at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:379)
    at io.netty.buffer.UnpooledUnsafeDirectByteBuf.setBytes(UnpooledUnsafeDirectByteBuf.java:447)
    at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:881)
    at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:242)
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:119)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:511)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354)
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)
    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)
    at java.lang.Thread.run(Thread.java:745)

如何以正确的方式关闭客户端连接？我是 netty 的新手

Answer 1

ctx.writeAndFlush 是异步的，因此可能会在数据实际写入 channel 之前 返回。但是，它返回一个 ChannelFuture，它允许您添加一个监听器，该监听器将在操作完成时收到通知。要确保仅在写入数据后关闭 channel ，您可以执行以下操作:

ctx.writeAndFlush("Not correct remote address! Connection closed")
        .addListener(ChannelFutureListener.CLOSE);