Java Server Client通信似乎陷入困境

时间:2016-06-19 13:02:09

标签: java sockets client-server communication

Hello stackoverflow社区,

我遇到了有关Java中套接字通信的问题。

以下是我的服务器和客户端类的示例代码:

服务器:

public class OTPServer {


static ServerSocket serverSocket;
final static int PORT = 4242;
static Socket clientConnection;

public static void main(String[] args) {

    try {
        serverSocket = new ServerSocket(PORT);
        System.out.println("Socket initialized");
        String serverMessage = "Hello, I am the Host";
        ServerTool serverTool = new ServerTool();

        while (true) {
            clientConnection = serverSocket.accept();
            if(clientConnection.isConnected()) {
                System.out.println("Client connected");
            }

            BufferedReader clientInputReader = new BufferedReader(new InputStreamReader(clientConnection.getInputStream()));
            DataOutputStream serverOutput = new DataOutputStream(clientConnection.getOutputStream());
            System.out.println("Sending message to client: " + serverMessage);
            serverOutput.writeBytes(serverTool.encodeMessage(serverMessage));
            serverOutput.flush();
            String clientMessage = clientInputReader.readLine();
            System.out.println("Encoded answer from client: " + clientMessage);
            String decodedMessage = serverTool.decodeMessage(clientMessage);
            System.out.println("Decoded answer from client: " + decodedMessage);

            serverOutput.close();
            clientInputReader.close();

        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    System.out.println("Hello, I am the OTP Server!");

}

以下是客户:

public class OTPClient {

static Socket clientSocket;
final static int PORT = 4242;
final static String HOST = "localhost";


public static void main(String[] args) {
    System.out.println("I am the OTP Client!");
    String serverMessage;
    String clientResponse = "I am the Client";
    OTPTool otpTool = new OTPTool();

    try {

        clientSocket = new Socket(HOST, PORT);
        BufferedReader serverInput = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        DataOutputStream outputStream = new DataOutputStream(clientSocket.getOutputStream());
        System.out.println("Connection to Host established");
        serverMessage = serverInput.readLine();
        System.out.println("Encoded Message from Server: " + serverMessage);
        String decodedMessage = otpTool.decodeMessage(serverMessage);
        System.out.println("Decoded message from Server: " + decodedMessage);
        System.out.println("Answering with own message: " + clientResponse);
        outputStream.writeBytes(clientResponse);
        outputStream.flush();
        outputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

现在我的问题在哪里:

连接建立,服务器似乎将其消息发送到客户端并等待答复。客户端不会打印从服务器获取的消息。 一旦我取消服务器,客户端就会打印出从服务器获取的消息以及发送答案的信息,退出代码为0,因此看起来这部分很好,只是卡在某种程度上。 我已经尝试刷新outputStream,就像在给出的示例代码中看到的那样。

是否有一些明显的遗失? 我知道,这是非常基本的东西,但它是我第一次使用套接字进行通信。

提前谢谢!

最诚挚的问候, 罗尼

顺便说一句:我知道服务器只连接到一个请求连接的客户端。这绝对足以让我使用。

1 个答案:

答案 0 :(得分:1)

它会卡住,因为serverInput.readLine();会阻塞,直到遇到换行符或文件结尾。在服务器端,您没有发送换行符,因此客户端阻止。