Question

最近，我一直在玩Java的网络和线程功能，我正在尝试开发一个多线程聊天应用程序。

问题是当客户端发送使用错误格式的消息时： “UserID #Message”而不是“UserID * Message”抛出异常，线程完全停止，客户端需要关闭其会话并再次重新打开它以重新建立与服务器的连接而不是在错误后重新开始，我无法恢复它。

这是服务器代码：

package AdvanceThreading.Server;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

public class Server {

    private ServerSocket serverSocket;
    private Socket socket;

    private DataInputStream messageFromClientToHandler;
    private DataOutputStream messageFromHandlerToRecipient;

    private int port;
    private static int userID;
    private ArrayList<ClientHandler> clientList;

    public Server(int port) {
        this.port = port;
        this.userID = 0;
        clientList = new ArrayList<>();
        this.initialize();
    }

    public void initialize() {
        try {
            serverSocket = new ServerSocket(port);
        } catch (IOException e) {
            e.printStackTrace();
        }

        while (true) {
            try {
                socket = serverSocket.accept();

                messageFromClientToHandler = new DataInputStream(socket.getInputStream());
                messageFromHandlerToRecipient = new DataOutputStream(socket.getOutputStream());

                String userName = messageFromClientToHandler.readUTF();

                messageFromHandlerToRecipient.writeInt(userID);

                ClientHandler client = new ClientHandler(userID, userName, this, socket, messageFromClientToHandler, messageFromHandlerToRecipient);

                clientList.add(client);

                //Should set client.setUncaughtExceptionHandler();

                client.start();

                userID = userID + 1;

            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public ServerSocket getServerSocket() {
        return serverSocket;
    }

    public Socket getSocket() {
        return socket;
    }

    public DataInputStream getMessageFromClientToHandler() {
        return messageFromClientToHandler;
    }

    public DataOutputStream getMessageFromHandlerToRecipient() {
        return messageFromHandlerToRecipient;
    }

    public int getPort() {
        return port;
    }

    public static int getUserID() {
        return userID;
    }

    public ArrayList<ClientHandler> getClientList() {
        return clientList;
    }

    public static void main(String[] args) {
        Server server = new Server(5050);
    }
}

客户端处理程序代码：

package AdvanceThreading.Server;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.StringTokenizer;

public class ClientHandler extends Thread {

    private int clientID;
    private String clientName;
    private boolean loggedIn;

    private Socket socket;

    private Server server;

    private DataInputStream messageFromClientToHandler;
    private DataOutputStream messageFromHandlerToRecipient;


    public ClientHandler(int clientID, String clientName, Server server, Socket socket, DataInputStream messageFromClientToHandler, DataOutputStream messageFromHandlerToRecipient) {
        this.clientID = clientID;
        this.clientName = clientName;
        this.loggedIn = true;
        this.server = server;
        this.socket = socket;
        this.messageFromClientToHandler = messageFromClientToHandler;
        this.messageFromHandlerToRecipient = messageFromHandlerToRecipient;
    }

    @Override
    public void run() {

        String receivedFromClient;
        StringTokenizer tokenize = null;

        while (true) {
            try {
                receivedFromClient = messageFromClientToHandler.readUTF();

                System.out.println(receivedFromClient);

                tokenize = new StringTokenizer(receivedFromClient, "#");
                String recipient = tokenize.nextToken();
                int recipientID = Integer.parseInt(tokenize.nextToken());
                String message = tokenize.nextToken();

                //Need to handle exception of client not found.

                for (ClientHandler client : server.getClientList()) {
                    if (client.getClientID() == recipientID && client.isLoggedIn()) {
                        client.getMessageFromHandlerToRecipient().writeUTF(this.clientName + ": " + message);
                        break;
                    }
                }
            } catch (IOException e) {
                while (tokenize != null && tokenize.hasMoreTokens())
                    tokenize.nextToken();

                e.printStackTrace();
            }
        }
    }

    public String getClientName() {
        return clientName;
    }

    public void setClientName(String clientName) {
        this.clientName = clientName;
    }

    public boolean isLoggedIn() {
        return loggedIn;
    }

    public void setLoggedIn(boolean loggedIn) {
        this.loggedIn = loggedIn;
    }

    public int getClientID() {
        return clientID;
    }

    public Socket getSocket() {
        return socket;
    }

    public Server getServer() {
        return server;
    }

    public DataInputStream getMessageFromClientToHandler() {
        return messageFromClientToHandler;
    }

    public DataOutputStream getMessageFromHandlerToRecipient() {
        return messageFromHandlerToRecipient;
    }
}

我想做的主要事情是，如果使用终端的客户端（例如：CMD）发生错误我想捕获错误处理它，并在同一终端上恢复他的会话，这样他就不必再次重新连接到服务器。

Answer 1

根据讨论，您可以使用RuntimeException捕获任何无效的相关数据重复：

  StringTokenizer tokenize = new StringTokenizer(receivedFromClient, "#");

        try {
            String recipient = tokenize.nextToken();

            int recipientID = Integer.parseInt(tokenize.nextToken());
            String message = tokenize.nextToken();
        } catch (RuntimeException e) {

            //ask client to resend the data
            continue
        }

捕获异常后如何在Java中恢复/重启线程？

1 个答案: