如何从netty中的HTTP服务器请求处理程序正确调用HTTP客户端? [英] How to call properly HTTP client from HTTP server request handler in netty?

问题描述

我正在使用netty 3.3.1开发自定义HTTP服务器.

I am developing custom HTTP server with netty 3.3.1.

我需要实现类似这样的东西

I need to implement something like this

1. HTTP Server收到请求
2. HTTP Server对其进行解析并作为其他计算机的客户端调用HTTP请求
3. HTTP Server等待(2)中发送的请求的响应
4. HTTP服务器根据(3)中收到的内容发送对(1)的请求的响应

这意味着客户端请求(2)必须表现为同步.

It means that client request (2) has to behave as synchronous.

我写的内容基于 HttpSnoopClient示例，但是它不起作用，因为我收到了

What I wrote is based on HttpSnoopClient example but it does not work, because I receive

java.lang.IllegalStateException: 
await*() in I/O thread causes a dead lock or sudden performance drop. Use addListener() instead or call await*() from a different thread. 

我重构了代码从上面提到的示例开始，现在看起来更像这样了(从HttpSnoopClient的第7f行开始):

I've refactored the code from the example mentioned above and now it looks more less like this (starting from line 7f of HttpSnoopClient):

    ChannelFuture future = bootstrap.connect(new InetSocketAddress(host, port));
    future.addListener(new ChannelFutureListener() {
      public void operationComplete(ChannelFuture future) {
        if (!future.isSuccess()) {
          System.err.println("Cannot connect"); 
            future.getCause().printStackTrace();
            bootstrap.releaseExternalResources();
            return;
          }
          System.err.println("Connected");

          Channel channel = future.getChannel();

          // Send the HTTP request.
          channel.write(request);
          channel.close();



          // Wait for the server to close the connection.
          channel.getCloseFuture().addListener(new ChannelFutureListener() {
            public void operationComplete(ChannelFuture future) {
              System.err.println("Disconnected"); 
              bootstrap.releaseExternalResources(); // DOES NOT WORK?
            }
          });   
        }
    });

  } 
}

上面的示例中的run()命令在我的herver处理程序的messageReceived函数中调用.

The run() command from the above example is invoked in the messageReceived function of my herver handler.

因此它变得异步并避免了await *函数.请求被正确调用.但是-由于我的未知原因-线

So it became asynchronous and avoid await* functions. Request is invoked properly. But - for uknown reason for me - the line

              bootstrap.releaseExternalResources(); // DOES NOT WORK?

不起作用.抛出一个异常，说我无法终止当前正在使用的线程(这听起来很合理，但仍然无法给出以其他方式执行此操作的答案).

does not work. It throws an exception saying that I cannot kill the thread I am currently using (which sounds reasonable, but still does not give me an answer how to do that in a different way).

我也不确定这是正确的方法吗?

I am also not sure is this a correct approach?

也许您可以推荐有关netty中此类事件编程技术的教程?通常如何处理一些必须按指定顺序调用并彼此等待的异步请求?

Maybe you can recommend a tutorial of such event programming techniques in netty? How to deal - in general - with a few asynchronous requests that has to be invoked in specified order and wait for each other?

谢谢

推荐答案

如果您确实想在关闭时释放引导程序，则可以这样做:

If you really want to release the bootstrap on close you can do it like this:

channel.getCloseFuture().addListener(new ChannelFutureListener() {
    public void operationComplete(ChannelFuture future) {
        System.err.println("Disconnected"); 
        new Thread(new Runnable() {
            public void run() {
                bootstrap.releaseExternalResources();
            }
        }).start();
    }
});   

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