Java套接字在终端上不发送数据

Question

我正在用 java 开发一个聊天应用程序，但我遇到了部署问题。 即使我的应用程序在通过 IDE（IntelliJ 中的服务器和 Netbeans 中的客户端）执行时运行顺利，但当我尝试通过终端运行服务器时，服务器无法正常工作。不正确是指服务器正在接收来自用户的消息，但它没有回复。

例如，客户端执行的前三个步骤是：

• 登录
• 获取用户列表
• 获取组列表

即使服务器正在接收这些消息/请求，它也不会回复。

我将每个与服务器的连接分配给一个新线程，因为那是一个多客户端应用程序。

知道发生了什么吗？

这是终端中输出的示例图片：

然后服务器就挂在那里了。

服务器实现

这是启动服务器的代码。

public class ThreadedServer {

ServerSocket serverSocket;
private static Socket welcomeSocket = null;

public ThreadedServer() {

    try {
        serverSocket = new ServerSocket(ServerConfiguration.SERVER_PORT);
        System.out.println("Server started");
    } catch (Exception e) {
        e.printStackTrace();
    }
    while (true) {
        try {
            welcomeSocket = serverSocket.accept();
            System.out.println("Connection accepted: " + welcomeSocket.getInetAddress() + ":" + welcomeSocket.getLocalPort());
            Thread t = new Thread(new ClientConnection(welcomeSocket));
            t.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

}

这是我处理收到的消息并发送我想要的消息的客户端连接类。

公共类 ClientConnection 实现 Runnable {

private final Socket clientSocket;
private DataInputStream dis;
private DataOutputStream dos;

private int sessionId;
private int userId;
private String username;
private ClientConnection self;

public ClientConnection(Socket client) {
    this.clientSocket = client;
    this.self = this;
}

public DataOutputStream getOutputStream() {
    return dos;
}

@Override
public void run() {
    System.out.println("Client Thread started!");
    initializeDataStreams();
    startListeningForMessages();

}

private void initializeDataStreams() {
    try {
        dis = new DataInputStream(clientSocket.getInputStream());
        dos = new DataOutputStream(clientSocket.getOutputStream());
        System.out.println("Server: Initialized Streams");
    } catch (IOException ex) {
        Logger.getLogger(ClientConnection.class.getName()).log(Level.SEVERE, null, ex);
    }
}


private void startListeningForMessages() {
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                String message;

                while ((message = dis.readUTF()) != null) {
                    System.err.println("Recieved from client: " + message);
                    if (ServerConfiguration.LOG_COMMUNICATION_MESSAGES) {
                        System.out.println("client message string recieved \" "
                                + message + " \"");
                    }
                    processMessage(message);
                }
            } catch (IOException ex) {
                // 1) Remove the connection from the list of connections.
                ConnectionManager.getInstance().removeConnection(self);
                // 2) Inform database for logout time AND Error Messege!
                DatabaseAction.logout(sessionId, "Unknown Error occurred");
            }
        }
    }).start();
}

private void processMessage(String messege) {
    Messege inbound = new Gson().fromJson(messege, Messege.class);
    if (inbound.getType() == MessegeType.login) {
        performLogin(inbound);
    } else if (inbound.getType() == MessegeType.logout) {
        performLogout(inbound);
    } else if (inbound.getType() == MessegeType.simple_messege) {
        sendMessege(inbound);
    } else if (inbound.getType() == MessegeType.group_messege) {
        sendGroupMessege(inbound);
    } else if (inbound.getType() == MessegeType.get_all_users) {
        getAllUsers();
    } else if (inbound.getType() == MessegeType.get_groups_im_involved_in) {
        getGroupsImInvolvedIn();
    } else if (inbound.getType() == MessegeType.get_messeges_from_user) {
        getMessegesFromUser(inbound);
    } else if (inbound.getType() == MessegeType.get_messeges_from_group) {
        getMessegesFromGroup(inbound);
    } else if (inbound.getType() == MessegeType.create_new_group) {
        createNewGroup(inbound);
    }
}


private void sendGroupMessege(Messege inbound) {
    new SendGroupMessegeAction(this, inbound);
}

public void close() {
    try {
        dis.close();
        dos.close();
        clientSocket.close();
    } catch (IOException ex) {
        Logger.getLogger(ClientConnection.class.getName()).log(Level.SEVERE, null, ex);
    }
}

private void performLogin(Messege messege) {
    LoginAction la = new LoginAction(messege.getUser(), messege, this);
    this.username = messege.getUser();
    this.sessionId = la.getSessionId();
    this.userId = la.getUserId();
}

private void performLogout(Messege messege) {
    new LogoutAction(this, messege);
}

public void sendMessege(Messege messege) {
    new SendSimpleMessegeAction(this, messege);
}

public int getSessionId() {
    return sessionId;
}

public int getUserId() {
    return userId;
}

public String getUsername() {
    return username;
}

private void getAllUsers() {
    try {
        System.out.println("Sending all users to client " + username);
        UsersObject uo = DatabaseAction.getAllUsers(userId);
        GetAllUsersMessege gaum = new GetAllUsersMessege(uo.getUsernames(), uo.areOnline(), uo.getHasSentMessegesThatAreUnread());
        Messege m = new Messege("", MessegeType.get_all_users, new Gson().toJson(gaum));
        System.out.println("Sent from server: " + new Gson().toJson(m));
        dos.writeUTF(new Gson().toJson(m));
        dos.flush();
    } catch (IOException ex) {
        Logger.getLogger(ClientConnection.class.getName()).log(Level.SEVERE, null, ex);
    }
}

这是从客户端

到服务器的连接

public class ServerConnection {

DataInputStream dis;
static DataOutputStream dos;
Socket socket;

public static ServerConnection instance;

public static ServerConnection getInstance() {
    if (instance == null) {
        instance = new ServerConnection();
    }
    return instance;
}

private ServerConnection() {
    initializeConnection();
    startListeningThread();
}

private void initializeConnection() {
    try {
        socket = new Socket(MyStatics.server_address, 3333);
        dis = new DataInputStream(socket.getInputStream());
        dos = new DataOutputStream(socket.getOutputStream());
        System.out.println("Client: Connection Initialized");

    } catch (IOException ex) {
        Logger.getLogger(ServerConnection.class
                .getName()).log(Level.SEVERE, null, ex);
    }
}

private void startListeningThread() {
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                String line = "";
                while (!socket.isClosed() && (line = dis.readUTF()) != null) {
                    System.out.println("Recieved from Server: " + line);
                    Messege m = new Gson().fromJson(line, Messege.class);
                    processMessege(m);
                }
            } catch (IOException ex) {
//                    Logger.getLogger(ServerConnection.class.getName()).log(Level.SEVERE, null, ex);

                if (!ex.getMessage().equals("Socket closed")) {
                    `enter code here`Logger.getLogger(ServerConnection.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
    }).start();
}

private void processMessege(Messege m) {
    if (m.getType() == MessegeType.get_all_users) {
        GetAllUsersMessege gaum = new Gson().fromJson(m.getEnv(), GetAllUsersMessege.class);
        MainWindow.usersData = gaum.getUsers();
        MainWindow.usersOnline = gaum.getOnline();
        MainWindow.usersWhoSentSomething = gaum.getHasSentMessegesThatAreUnread();
        MainWindow.changeData();
    } else if (m.getType() == MessegeType.get_groups_im_involved_in) {
        GetGroupsImInvolvedInMessege ggiiim = new Gson().fromJson(m.getEnv(), GetGroupsImInvolvedInMessege.class);
        MainWindow.groupsData = ggiiim.getGroups();
        MainWindow.changeData();
    } else if (m.getType() == MessegeType.simple_messege) {
        SimpleMessege sm = new Gson().fromJson(m.getEnv(), SimpleMessege.class);
        MainWindow.informThatMessegeIsRecieved(m.getUser());
        System.out.println("Recieved simple messege");
        for (ChatBox chatBox : MyInstances.chatBoxes) {
            if (chatBox.getTo().equals(m.getUser())) {
                System.out.println("Chatbox was found");
                chatBox.appendRecievedMessege(sm.getMessege());
            }
        }

   ...
   ...
    }
 }

编辑：我添加了代码 sn-ps。

Answer 1

可能的问题（不确定）：
0) 关于readUTF和writeUTF
IDE 可能以字符集（可能是 UTF-8）调用服务器和客户端，而在终端中您不设置它，因此它继承自 OS。

在您的终端中，将字符集设置为 UTF-8（用于服务器和客户端），然后重试。例如(java -Dfile.encoding=utf-8 -jar <<your jar server/client>>)

另外，如果您总是从服务器和客户端发送纯字符串（没有原始/二进制），那么您可以使用 BufferedReader 和 PrintStream/PrintStream 而不是 DataInputReader 和 Writer。

1) 为确保您运行的是最新/正确的文件，请在 netbeans 中始终右键单击项目并进行清理和构建操作。

希望对你有帮助。