Netty（6）关闭

 

客户端：

public static void main(String[] args) throws Exception {
    final SslContext sslCtx;
    if (SSL) {
        sslCtx = SslContextBuilder.forClient().trustManager(InsecureTrustManagerFactory.INSTANCE).build();
    } else {
        sslCtx = null;
    }
    EventLoopGroup group = new NioEventLoopGroup();
    try {
        Bootstrap b = new Bootstrap();
        b.group(group)
        .channel(NioSocketChannel.class)
        .handler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
                ChannelPipeline p = ch.pipeline();
                if (sslCtx != null) {
                    p.addLast(sslCtx.newHandler(ch.alloc(),HOST,PORT));
                }
                p.addLast(new DiscardClientHandler());
            }
        });
        //make the connection attempt.
        ChannelFuture f = b.connect(HOST,PORT).sync();
        //wait until the connection is closed.
        f.channel().closeFuture().sync();
        log.info("connection is closed");
    } finally {
        group.shutdownGracefully();
    }
}

或者

public static void main(String[] args) throws Exception {
    EventLoopGroup group = new NioEventLoopGroup();
    try {
        Bootstrap b = new Bootstrap();
        b.group(group)
        .channel(NioSocketChannel.class)
        .handler(new TelnetClientInitializer());
        
        
        Channel ch = b.connect(HOST, PORT).channel();
        //read commands from the stdbin.
        ChannelFuture lastWriteFuture = null;
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        for(;;) {
            String line = in.readLine();
            if (line == null) {
                break;
            }
            //send the received line to the server
            lastWriteFuture = ch.writeAndFlush(line +"
");
            //if user typed the 'bye' command,wait unitl the server closes the connection.
            if ("bye".equals(line.toLowerCase())) {
                ch.closeFuture().sync();
                break;
            }
        }
        //wait unitl all messages are flushed before closing the channel.
        if (lastWriteFuture != null) {
            lastWriteFuture.sync();
        }
    } finally {
        group.shutdownGracefully();
    }
}

或者

@Override
protected void channelRead0(ChannelHandlerContext ctx, BigInteger msg) throws Exception {
    receivedMessages ++;
    if (receivedMessages == FactorialClient.COUNT-start+1) {
        //offer（放入）the answer after closing the connection
        ctx.channel().close().addListener(new ChannelFutureListener() {
            @Override
            public void operationComplete(ChannelFuture future) throws Exception {
                boolean offered = answer.offer(msg);
                log.info("offer the answer result:{}",offered);
            }
        });
    }
}

服务端：

1、继承SimpleChannelInboundHandler或ChannelInboundHandlerAdapter的server端

@Override
protected void channelRead0(ChannelHandlerContext ctx, String request) throws Exception {
    //Generate and write a response
    String response;
    boolean close = false;
    if (request.isEmpty()) {
        response = "Please type something.
";
    } else if("bye".equals(request.toLowerCase())) {
        response = "Have a good day!
";
        close = true;
    } else {
        response = "Did you say '"+request+"'?
";
    }
    //不需要write ByteBuf，只需write string，因为传递给StringEncoder
    ChannelFuture future = ctx.write(response);
    if (close) {
        future.addListener(ChannelFutureListener.CLOSE);
    }
}

如果是短链接，必须在服务端关闭该channel。此时，才能通知到客户端的chanel.future.close()方法。

2、需要解码器（decoder）的server端

在serverHandler类中的channelRead方法中，无需加入future.addListener(ChannelFutureListener.CLOSE);如下，

@Override
protected void channelRead0(ChannelHandlerContext ctx, BigInteger msg) throws Exception {
    //计算阶乘并发送到客户端
    lastMultiplier = msg;
    factorial = factorial.multiply(msg);
    ctx.writeAndFlush(factorial);
}

因为，ByteToMessageDecoder类中，已执行了关闭，如下

@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
    channelInputClosed(ctx, true);
}