Java DataOutputStream在断开连接时不会引发IOException

Question

DataOutputStream doesn't throw an IOException when I plug my cable out, what's wrong with my code?

Here is my code:

private void sendMessage(String message) {
    try {
        mDataOutputStream.writeUTF(message);
        mDataOutputStream.flush();
    } catch(IOException ex) {
        close();
    }
}

As soon as I plug the cable back in, the data is still sent to the server.

Answer 1

TCP connection are designed to cope with short term failures gracefully, and transparently where possible. This means when the connection is lost for short period eg less than 3 minutes, the connection should re-establish itself transparently. Even if the connection has timed out you will not know asynchronously, it may be the next read or write which fails.