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将InputStream（阻塞）的内容写入非阻塞套接字

[英]Write contents of an InputStream (blocking) to a non-blocking socket

原文 2011-04-05 07:38:06 3 2 java/ inputstream/ nio

I'm programming a simple Java NIO server and have a little headache: I get normal InputStream si need to pipe to my clients. 我正在编写一个简单的Java NIO服务器并且有点头疼：我得到普通的InputStream需要管道到我的客户端。 I have a single thread performing all writes, so this creates a problem: if the InputStream blocks, all other connection writing will be paused. 我有一个线程执行所有写操作，因此这会产生一个问题：如果InputStream阻塞，所有其他连接写入将被暂停。

I can use InputStream.available() to check if there are any incoming data I can read without blocking, but if I've reached end-of-stream it seems I must call read() to know. 我可以使用InputStream.available()来检查是否有任何传入的数据我可以无阻塞地读取，但如果我已经到达流末尾，我似乎必须调用read()才能知道。

This creates a major headache for me, but I can't possibly believe I'm the first to have this problem. 这给我带来了很大的麻烦，但我不可能相信我是第一个遇到这个问题的人。

The only options I've come up with so far: 到目前为止我提出的唯一选择：

Have a separate thread for each InputStream , however that's just silly since I'm using non-blocking I/O in the first place. 为每个InputStream都有一个单独的线程，但这只是愚蠢的，因为我首先使用的是非阻塞I / O. I could also have a thread pool doing this but then again that limits the amount of simultaneous clients I can pipe the InputStream to. 我也可以让一个线程池执行此操作但是再次限制了我可以将InputStream传递给的并发客户端的数量。
Have a separate thread reading these streams with a timeout (using another thread to interrupt if reading has lasted longer than a certain amount of time), but that'll most certainly choke the data flow should I have many open InputStream s not delivering data. 有一个单独的线程读取这些流超时（如果读取持续时间超过一定的时间，则使用另一个线程来中断），但如果我有许多打开的InputStream不提供数据，那么这肯定会阻塞数据流。

Of course, if there was a magic InputStream.isEof() or isClosed() then this wouldn't be any problem at all :'( 当然，如果有一个神奇的InputStream.isEof()或isClosed()那么这根本不会有任何问题：'（

2 个解决方案

" .....Have a separate thread for each InputStream, however that's just silly since I'm using non-blocking I/O in the first place.... " “ .....每个InputStream都有一个单独的线程，但是这很愚蠢，因为我首先使用非阻塞I / O ...... ”

It's not silly at all. 这根本不是愚蠢的。 First you need to check whether you can retrieve a SelectableChannel from your InputStream implementation. 首先，您需要检查是否可以从InputStream实现中检索SelectableChannel。 If it does you are lucky and you can just register it with a selector and do as usual. 如果确实如此，你很幸运，你可以用选择器注册它并像往常一样。 But chances are that your InputStream may have a channel that's not a SelectableChannel, in which case "Have a separate thread for each InputStream" is the obvious thing to do and probably the right thing to do. 但是很有可能你的InputStream可能有一个不是SelectableChannel的通道，在这种情况下“为每个InputStream创建一个单独的线程”是显而易见的事情，可能是正确的事情。

Note that there is a similar problem discussed in SO about not able to get a SelectableChannel from an inputstream . 请注意，在SO中讨论的类似问题是无法从输入流获取SelectableChannel 。 Unfortunately you are stuck. 不幸的是你被困住了。