java - 测试客户端服务器

Question

我编写了一个监听客户端消息的服务器，它是 http://docs.oracle.com/javase/tutorial/networking/sockets/clientServer.html 的变体。我在 eclipse 中将它们作为同一项目中的 java 类编写。为了测试它，我有一个带有 main 的客户端类，该类启动服务器然后向其发送消息。当我运行它时，程序只是卡在 serverSocket.accept(); 处。根据ServerSocket接受的javadoc不是异步的？这可以解释挂起的情况，但是教程代码是如何工作的呢？

更新 - 这是我的工作代码: 这是工作代码:

MyServer.java

/*imports neglected for brevity */
public class MyServer {
public static final String hostname = "localhost";
public static final int portNum = 4444;

ServerSocket serverSocket;
BufferedReader serverReader;

File serverLog;
FileWriter fw;
BufferedWriter serverWriter;

Socket clientSocket;

public static void main(String[] args) {
MyServer server = new MyServer(portNum);
    // start the server so it can listen to client messages
    server.start();


}


public MyServer(int portNum) {

    try {
        // endpt for server side, used to listen for client socket
        serverSocket = new ServerSocket(portNum);

        /* have server socket listen for connection, return client socket.
         * serverSocket can now talk to clientSocket
         */
        clientSocket = serverSocket.accept();

        // server writes messages to this log
        serverLog = new File("ServerLog.txt");
        if(!serverLog.exists())
            serverLog.createNewFile();
        fw = new FileWriter(serverLog.getAbsoluteFile());
        serverWriter = serverWriter = new BufferedWriter(fw);

        /* server reads from this stream that is populated by the client's
         * OUTPUT stream/client socket's INPUT stream
         */
        serverReader = new BufferedReader(
            new InputStreamReader(clientSocket.getInputStream())
                                              );
    }    
    catch (Exception e) {
        e.printStackTrace();
    }
}

public void start() {
    String clientMsg;
    try {
        while((clientMsg = serverReader.readLine()) != null) {
            if(clientMsg.startsWith("exit")) {
                break;
            }
            serverWriter.append(clientMsg);
        }
        serverWriter.flush();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

}

MyClient.java 公共(public)类 MyClient { 公共(public)静态最终字符串主机名=“localhost”； 公共(public)静态最终 int portNum = 4444;

public static void main(String[] args) {

    String msg = "message 1";
    try {
        // server is listening on http://localhost:4444
        Socket serversSocket = new Socket(hostname, portNum);
        PrintWriter clientOut = new     PrintWriter(serversSocket.getOutputStream(), true);

        // send first message
        clientOut.println(msg);

        msg = "message 2";
        // send second message
        clientOut.println(msg);

        msg = "exit";
        // this will stop the server
        clientOut.println(msg);
    }
    catch (Exception e) {
        e.printStackTrace();
    }
}

}

Answer 1

如果您完成本教程，它会创建两个应用程序，一个带有客户端，一个带有服务器。

您不能创建这样的变体，因为当您调用构造函数时，整个应用程序会在 clientSocket = serverSocket.accept(); 中阻塞。

如果您出于某种原因坚持创建单个应用程序，则可以进行多线程处理。但我看不出您有任何理由要这样做。