Question

我试图编写一个Server Client程序，如果SERVER关闭或失去连接，将提示客户端。一旦我连接服务器和客户端然后断开它没有进入ConnectException部分的服务器，会发生什么示例：我打开了服务器和客户端连接，在客户端中它将显示＆＃34;您已连接到服务器＆＃34;，然后如果服务器断开连接，则应该有一个＆＃34;服务器已断开连接＆＃34; 。当服务器重新打开时，它将提示客户端他已连接到服务器

如何连续检查服务器是打开还是断开连接

这是我的代码：

服务器

   public class Server
{
    private static Socket socket;

    public static void main(String[] args)
    {
        try
        {
            int port = 25000;
            ServerSocket serverSocket = new ServerSocket(port);
            //Server is running always. This is done using this while(true) loop
            while(true)
            {
                //Reading the message from the client
                socket = serverSocket.accept();
                System.out.println("Client has connected!");
                InputStream is = socket.getInputStream();
                InputStreamReader isr = new InputStreamReader(is);
                BufferedReader br = new BufferedReader(isr);
                String number = br.readLine();
                System.out.println("Message received from client is "+number);

                //Multiplying the number by 2 and forming the return message
                String returnMessage;
                try
                {
                    int numberInIntFormat = Integer.parseInt(number);
                    int returnValue = numberInIntFormat*2;
                    returnMessage = String.valueOf(returnValue) + "\n";
                }
                catch(NumberFormatException e)
                {
                    //Input was not a number. Sending proper message back to client.
                    returnMessage = "Please send a proper number\n";
                }

                //Sending the response back to the client.
                OutputStream os = socket.getOutputStream();
                OutputStreamWriter osw = new OutputStreamWriter(os);
                BufferedWriter bw = new BufferedWriter(osw);
                bw.write(returnMessage);
                System.out.println("Message sent to the client is "+returnMessage);
                bw.flush();
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

客户端

    public class Client
{
    private static Socket socket;

    public static void main(String args[])
    {
        Scanner input=new Scanner(System.in);

        try
        {
            String host = "localhost";
            int port = 25000;
            InetAddress address = InetAddress.getByName(host);
            socket = new Socket(address, port);
            System.out.println("Connected to the Server");
        }
        catch (ConnectException exception)
        {
            System.out.println("Server is still offline");
        }
        catch(IOException ex)
        {
            System.out.println("Server got disconnected");
        }
    }
}

Answer 1

那么，判断连接是否中断的最佳方法是尝试从套接字读取/写入。如果操作失败，那么您有时会丢失连接。

因此，您需要做的就是尝试在某个时间间隔读取，如果读取失败，请尝试重新连接。

对于您来说，重要的事件是当读取失败时 - 您丢失连接，并且当连接新套接字时 - 您重新获得连接。

通过这种方式，您可以跟踪正常运行时间和停机时间。

你可以这样做

try
{
    Socket s = new Socket("address",port);
    DataOutputStream os = new DataOutputStream(s.getOutputStream());
    DataInputStream is = new DataInputStream(s.getInputStream());
    while (true)
    {
        os.writeBytes("GET /index.html HTTP/1.0\n\n");
        is.available();
        Thread.sleep(1000);
   }
}
catch (IOException e)
{
    System.out.println("connection probably lost");
    e.printStackTrace();
}

或者您可以像socket.setSoTimeout(timeout);这样简单地连接超时以检查连接性或者你可以使用

socket.getInputStream().read()

只要服务器连接，

使线程等待输入，因此使你的程序不做任何事情 - 除非你得到一些输入和如果客户端断开连接则返回-1 或者你能做的就是以这种方式构建你的代码

while(isConnected())
  {
      // do stuffs here
  }

java Socket编程服务器客户端

1 个答案: