从服务器访问其他服务时连接似乎消失

Question

每当我尝试从WebSocket服务器访问任何服务时，我的WebSocket连接似乎都消失了。

我尝试调用e.printStackTrace（），这给了我NoSuchElementException：没有值出现错误。

这是我的服务器：

package _Server_Side.Server.config;

import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

import _Server_Side.Server.Entities.User_Entity;
import _Server_Side.Server.Repositories.User_repo;
import _Server_Side.Server.Services.User_Service;

@Service
@ServerEndpoint(value = "/websocket/{username}", configurator = CustomSpringConfigurator.class)
public class WebSocketServer {

    private static Map<Session, String> sessionUsernameMap = new HashMap<>();
    private static Map<String, Session> usernameSessionMap = new HashMap<>();
    private static Map<String, Boolean> isblockeduser = new HashMap<>();

    @Autowired
    private User_Service user_Service;

    @Autowired
    private User_repo userRepo;

    private final Logger logging = LoggerFactory.getLogger(WebSocketServer.class);

    /**
     * 
     * @param session
     * @param username
     * @throws IOException
     */
    @OnOpen
    public void onOpen(Session session, @PathParam("username") String username) throws IOException {
        logging.info("Entered into Open");

        sessionUsernameMap.put(session, username);
        usernameSessionMap.put(username, session);
        if (username.equals("a")) {
            isblockeduser.put("a", true);
        }

注释行是导致问题的原因

//User_Entity  user = userRepo.findById(2).get();
        //System.out.println(user.getGroups().toString());
        String message = "User:" + username + " has Joined the Chat";
        //System.out.println(user_Service.returngroup(2));
        broadcast(message);



    }

    /**
     * 
     * @param session
     * @param username
     * @throws IOException
     */

    @OnMessage
    public void onMessage(Session session, String message) throws IOException {
        // Handle new messages
        logging.info("Entered into Message: Got Message:" + message);
        String username = sessionUsernameMap.get(session);
        if (isblocked(session)) {
            sendMessageToPArticularUser(username, "[DM] " + username + ": " + "You are blocked from this chat");
        } else {
            if (message.startsWith("@")) // Direct message to a user using the format "@username <message>"
            {
                String destUsername = message.split(" ")[0].substring(1); // don't do this in your code!
                sendMessageToPArticularUser(destUsername, "[DM] " + username + ": " + message);
                sendMessageToPArticularUser(username, "[DM] " + username + ": " + message);
            } else // Message to whole chat
            {
                broadcast(username + ": " + message);
            }

            System.out.println(user_Service.getAllUsers());
            boolean status = user_Service.save_data(message);

        }
    }

    /**
     * 
     * @param session
     * @param username
     * @throws IOException
     */

    @OnClose
    public void onClose(Session session) throws IOException {
        logging.info("Entered into Close");

        String username = sessionUsernameMap.get(session);
        sessionUsernameMap.remove(session);
        usernameSessionMap.remove(username);

        String message = username + " disconnected";
        broadcast(message);
    }

    /**
     * 
     * @param session
     * @param username
     * @throws IOException
     */

    @OnError
    public void onError(Session session, Throwable throwable) {

        logging.info("Entered into Error");
        throwable.printStackTrace() ;
    }

    /**
     * 
     * @param session
     * @param username
     * @throws IOException
     */

    private void sendMessageToPArticularUser(String username, String message) {
        try {
            usernameSessionMap.get(username).getBasicRemote().sendText(message);
        } catch (IOException e) {
            logging.info("Exception: " + e.getMessage().toString());
            e.printStackTrace();
        }
    }

    /**
     * 
     * @param session
     * @param username
     * @throws IOException
     */

    private boolean isblocked(Session session) {
        String username = sessionUsernameMap.get(session);
        if (isblockeduser.containsKey(username) && isblockeduser.get(username) == true)
            return true;
        return false;

    }

    /**
     * 
     * @param session
     * @param username
     * @throws IOException
     */
    private static void broadcast(String message) throws IOException {
        sessionUsernameMap.forEach((session, username) -> {
            synchronized (session) {
                try {
                    session.getBasicRemote().sendText(message);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        });
    }
}


This is the code that I am trying to access from my WebSocket:


    public Group_Entity returngroup(int id) {
        System.out.println("here");
        User_Entity user=getUser(id);
        Iterator<Group_Entity> it = user.getGroups().iterator();
        if(it.hasNext())
            return it.next();
        return null;


    }


}

我正在尝试获取群组ID，以便可以与其中的群组成员进行单独的聊天