在准备好读取的多个套接字中进行选择 [英] selecting among multiple sockets that are ready to be read from

问题描述

我正在编写服务器客户端应用程序。我有一个服务器，它拥有我从ServerSocket的accept（）方法获得的几个套接字。我想从这些套接字读取，但我不知道哪个套接字可以读取。我需要某种选择器来选择其中一个可以读取的套接字，这样我就可以读取它发送的数据了。

I am writing a server-client application. I have a server that holds several sockets that I have got from the accept() method of ServerSocket. I want to read from these sockets but I don't necesserally know which socket is ready to be read from. I need some kind of selector that will select one of the sockets that are ready to be read from, so I can read the data it sends.

谢谢。

推荐答案

你基本上有两个选项可以让它发挥作用：

You have basically two options to make it work:

1. 每个接受的套接字都有专用线程。这是因为'常规'套接字I / O正在阻塞。您无法使用单个线程有选择地处理多个套接字。由于没有偷看功能，当您调用读取时，您将始终面临被阻止的风险。通过为每个有兴趣读取的套接字创建一个线程，阻塞读取不会阻止任何其他操作（线程）。


2. 使用NIO。 NIO允许异步I / O操作，基本上就是你要求的 - 选择器。

1. Have dedicated thread per accepted socket. This is because the 'regular' socket I/O is blocking. You can not selectively handle multiple sockets using a single thread. And as there is no 'peeking' functionality, you will always take a risk of getting blocked when you invoke read. By having a thread per each socket you are interested in reading, blocking reads will not block any other operations (threads).
2. Use NIO. NIO allows for asynchronous I/O operations, and basically exactly what you asked for - a Selector.

如果您决定采用NIO方式，我建议您查看 MINA 和 Netty 。我发现它们比普通的NIO更容易使用。您不仅可以获得更好的API，而且至少MINA也可以解决一些令人讨厌的NIO错误。

If you do decide to go NIO-way, I would recommend checking out MINA and Netty. I've found them much easier to work with than plain NIO. Not only will you get a nicer API to work with, but at least MINA had workarounds for some nasty NIO bugs, too.

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