Netty Http客戶端：如何將客戶端啟動，發送請求和客戶端關閉分為不同的方法

Question

1.背景
我發現使用Netty的大多數http客戶端示例似乎都遵循以下代碼結構：

public void run() {
    EventLoopGroup group = new NioEventLoopGroup();
    try {
        Bootstrap b = new Bootstrap();
        b.group(group)
         .channel(NioSocketChannel.class)
         .handler(new HttpSnoopClientInitializer(sslCtx));

        // Make the connection attempt.
        Channel ch = b.connect(host, port).sync().channel();
        // send something
        ch.writeAndFlush(XXXX);
        // Wait for the server to close the connection.
        ch.closeFuture().sync();
    } finally {
        // Shut down executor threads to exit.
        group.shutdownGracefully();
    }
}

因此，如果我正確理解它，那么每次發送請求時，都需要創建一個客戶端，並在其上調用client.run() 。 也就是說，似乎我一次只能發出一個“固定”請求。

2.我的需要
我需要一個可以發送多個請求的老客戶。 更具體地說，將有另一個線程向客戶端發送指令，並且每當客戶端獲得指令時，它將發送一個請求。 像這樣：

Client client = new Client();
client.start();

client.sendRequest(request1);
client.sendRequest(request2);
...
client.shutDownGracefully(); // not sure if this shutdown is necessary or not
// because I need a long-standing client to wait for instructions to send requests
// in this sense it's kinda like a server.

3，我嘗試過的
我已經嘗試過這樣的事情： 通過此鏈接

public MyClient(String host, int port) {
    System.out.println("Initializing client and connecting to server..");
    EventLoopGroup workerGroup = new NioEventLoopGroup();

    Bootstrap b = new Bootstrap();
    b.group(workerGroup)
        .channel(NioSocketChannel.class)
        .option(ChannelOption.SO_KEEPALIVE, true)
        .handler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel channel) throws Exception {
                channel.pipeline().addLast(new StringDecoder());
                channel.pipeline().addLast(new StringEncoder());
                channel.pipeline().addLast(new MyAppClientHandler());
            }
        });

    channelFuture = b.connect(host, port);
}

public ResponseFuture send(final String msg) {
    final ResponseFuture responseFuture = new ResponseFuture();

    channelFuture.addListener(new GenericFutureListener<ChannelFuture>() {
        @Override
        public void operationComplete(ChannelFuture future)
                throws Exception {
            channelFuture.channel().pipeline().get(MyAppClientHandler.class).setResponseFuture(responseFuture);
            channelFuture.channel().writeAndFlush(msg);                             
        }
    });

    return responseFuture;
}

public void close() {
    channelFuture.channel().close();        
}

問題是似乎此代碼未調用workerGroup.shutDownGracefully() ，因此我猜測這可能會有問題。 有沒有辦法將“啟動客戶端”，“發送請求”，“關閉客戶端”拆分為單獨的方法？ 提前致謝！

Answer 1

最簡單的解決方案是使用ChannelPool提供的ChannelPool ： https ：//netty.io/news/2015/05/07/4-0-28-Final.html

它提供開箱即用的gracefulshutdown ， maxconnections等。