Question

class CheckServerStarted implements Closeable
    {
        private final SocketChannel channel;
        private final InetSocketAddress address;
        private boolean connStarted = false;

        public CheckServerStarted(InetSocketAddress address) throws IOException
        {
            channel = SocketChannel.open();
            channel.configureBlocking(false);

            this.address = address;
        }

        /**
         * @throws IOException 
         * 
         */
        private void startConn() throws IOException
        {
            channel.connect(address);
            connStarted = true;
        }

        private boolean check(int timeout, boolean retry)
        {
            for (int i = 0; i < timeout; i++)
            {
                try
                {
                    final boolean justStarted = !connStarted;
                    if (justStarted)
                    {
                        startConn();
                    }

                    if (justStarted || (i > 0))
                    {
                        // Wait a second between attempts/give the connection some time to get established.
                        try
                        {
                            Thread.sleep(1000);
                        }
                        catch (InterruptedException e)
                        {
                            throw new RuntimeException(e);
                        }
                    }

                    if (channel.finishConnect())
                    {
                        System.out.println("Server started - accepting connections on " + address.toString());
                        return true;
                    }
                }
                catch (IOException e)
                {
                    System.out.println("Connect attempt failed : " + e.getMessage());
                    if (!retry)
                    {
                        break;
                    }

                    // Try to start the connection again if it failed.
                    connStarted = false;
                }
            }

            System.out.println("Connect attempt to " + address.toString() + " failed, ran out of time/attempts");
            return false;
        }

        /* (non-Javadoc)
         * @see java.io.Closeable#close()
         */
        public void close()
        {
            try
            {
                channel.close();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }
    }

我有以下代码，用于等待/检查服务器启动＆amp;正在听一个给定的地址/端口。

我的想法是，我可以，例如，呼叫

new CheckServerStarted(addr).check(60, true);

尝试连接它最多60秒（如果连接失败，则重试，因为服务器尚未绑定套接字）

或

new CheckServerStarted(addr).check(1, false);

检查服务器当前是否正在接受连接。

当我现在运行第一个例子时，我得到像

这样的输出

Connect attempt failed : Connection refused: no further information
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt failed : null
14-Jun-2018 10:55:42    Connect attempt to /192.168.223.68:59695 failed, ran out of time/attempts

显然不会在尝试之间等待1秒。

我猜我需要在两次尝试之间“重置”频道？我是否每次都需要创建一个新的？

Answer 1

即使连接尝试失败，也无法重新连接已连接的套接字。必须关闭它并创建一个新的。

其他问题：

你正在泄漏插座。
摆脱睡眠并使用Selector。
打印e而不是e.getMessage()。如果您首先正确地做到了这一点，而不是仅仅盯着＆＃39; null＆＃39;整天，你可能已经自己解决了这个问题。
IOException来电finishConnect()是致命的，而不是重试的信号。

检查端口是否绑定＆amp;用Java听; '重置'SocketChannel？

1 个答案: