用 SocketChannel.open().socket() 替换 new Socket() 有什么问题吗？

Question

What can go wrong if I simply replace

socket = new Socket()

with

socket = SocketChannel.open().socket()?

Background: I have some legacy code using new Socket() , and I wanted to be able to interrupt the socket.connect() call. I don't want to rewrite the code to use NIO. I learned that Thread.interrupt() does not interrupt socket.connect() , but that socket.close() on another thread is supposed to interrupt the connection. Oddly, that worked with Java 7 but not Java 6.

I somehow got it into my head that using socket = SocketChannel().open().socket() would magically allow me to use Thread.interrupt() to interrupt socket.connect() . It doesn't, but oddly, it does make socket.close() interrupt socket.connect() in Java 6 too!

Note that I'm not directly using the attached SocketChannel in any way---it appears when I create the Socket and never again.

What can go wrong with this?

Answer 1

There are several.

1. A Socket acquired via a SocketChannel doesn't appear to support read timeouts.
2. The InputStream and OutputStream of a socket aren't independent: they have a mutual lock in common.

Why do you want to interrupt the connect() call? Surely all you want is a connect timeout?

Answer 2

Differences in the type of thrown exceptions could break existing code.

For instance, closing a Socket from a different thread while Socket.getInputStream().read() is blocking will result in AsynchronousCloseException after replacing, instead of SocketException that legacy code could be expecting. ( AsynchronousCloseException is not a subclass of SocketException .)

However, Socket.getInputStream().read() will still throw SocketException if the close from the other thread gets in before read() .