Java 网络服务扫描器

Question

我正在尝试编写一个类来扫描本地网络以查找将要运行的服务。

问题是，如果地址不活跃（没有回复），它会挂断 5 秒以上，这是不好的。

我想在几秒钟内完成此扫描。谁能给点建议？

我的代码部分如下

        int port = 1338;
    PrintWriter out = null;
    BufferedReader in = null;

    for (int i = 1; i < 254; i++){

        try {
            System.out.println(iIPv4+i);
            Socket kkSocket = null;

            kkSocket = new Socket(iIPv4+i, port);

            kkSocket.setKeepAlive(false);
            kkSocket.setSoTimeout(5);
            kkSocket.setTcpNoDelay(false);  

            out = new PrintWriter(kkSocket.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(kkSocket.getInputStream()));
            out.println("Scanning!");
            String fromServer;
            while ((fromServer = in.readLine()) != null) {
                System.out.println("Server: " + fromServer);
                if (fromServer.equals("Server here!"))
                    break;
            }

        } catch (UnknownHostException e) {

        } catch (IOException e) {

        }
    }

感谢您的回答！这是我的代码，供其他人寻找！

        for (int i = 1; i < 254; i++){

        try {
            System.out.println(iIPv4+i);
            Socket mySocket = new Socket();
            SocketAddress address = new InetSocketAddress(iIPv4+i, port);

            mySocket.connect(address, 5);   

            out = new PrintWriter(mySocket.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(mySocket.getInputStream()));
            out.println("Scanning!");
            String fromServer;
            while ((fromServer = in.readLine()) != null) {
                System.out.println("Server: " + fromServer);
                if (fromServer.equals("Server here!"))
                    break;
            }

        } catch (UnknownHostException e) {

        } catch (IOException e) {

        }
    }

Answer 1

您可以尝试通过调用 Socket.connect( address, timeout ) 显式连接到服务器。

 Socket kkSocket = new Socket();
 kkSocket.bind( null )/ // bind socket to random local address, but you might not need to do this
 kkSocket.connect( new InetSocketAddress(iIPv4+i, port), 500 ); //timeout is in milliseconds

Answer 2

您可以使用 noarg 构造函数 Socket() 创建一个未连接的套接字，然后使用一个小的超时值调用 connect(SocketAddress endpoint, int timeout)。

Socket socket = new Socket();
InetSocketAddress endpoint = new InetSocketAddress("localhost", 80);
int timeout = 1;
socket.connect(endpoint, timeout);