我的 Java 多线程 TCP 服务器经常崩溃

Question

So i know this is a big one with a lot of code but i dont know what the issue is as the login system seems to work fine but when i try to add a bug or view a bug it will crash the server and i have to restart Server:

import java.io.*;
import java.net.*;
import java.util.*;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

public class Server
{
    // User database
    private static Map<String, String> userDatabase = new HashMap<>();

    // Bug report database
    private static Map<Integer, String> bugDatabase = new HashMap<>();
    private static int nextBugId = 1;

    public static void main(String[] args) throws Exception
    {
        // Create a server socket
        ServerSocket welcomeSocket = new ServerSocket(6789);

        // Create a thread pool with a fixed number of threads
        Executor executor = Executors.newFixedThreadPool(10);

        while (true)
        {
            // Accept a new client connection
            Socket connectionSocket = welcomeSocket.accept();

            // Create a new thread for the client and submit it to the thread pool
            Runnable clientHandler = new ClientHandler(connectionSocket);
            executor.execute(clientHandler);
        }
    }

    // Inner class for handling client requests
    private static class ClientHandler implements Runnable
    {
        private Socket connectionSocket;
        private BufferedReader inFromClient;
        private DataOutputStream outToClient;

        public ClientHandler(Socket socket) throws Exception
        {
            connectionSocket = socket;
            inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
            outToClient = new DataOutputStream(connectionSocket.getOutputStream());
        }

        public void run()
        {
            try
            {
                // Read request from the client
                String request = inFromClient.readLine();

                if (request.startsWith("REGISTER"))
                {
                    // Parse the request
                    String[] tokens = request.split(" ");
                    String username = tokens[1];
                    String password = tokens[2];

                    // Check if the username is already taken
                    if (userDatabase.containsKey(username))
                    {
                        outToClient.writeBytes("ERROR: Username already taken\n");
                    }
                    else
                    {
                        // Add the user to the database
                        userDatabase.put(username, password);
                        outToClient.writeBytes("OK\n");
                    }
                }
                else if (request.startsWith("LOGIN"))
                {
                    // Parse the request
                    String[] tokens = request.split(" ");
                    String username = tokens[1];
                    String password = tokens[2];

                    // Check if the username and password are correct
                    if (!userDatabase.containsKey(username))
                    {
                        outToClient.writeBytes("ERROR: Invalid username\n");
                    }
                    else if (!userDatabase.get(username).equals(password))
                    {
                        outToClient.writeBytes("ERROR: Invalid password\n");
                    }
                    else
                    {
                        outToClient.writeBytes("OK\n");
                    }
                }
                else if (request.startsWith("ADD"))
                {
                    // Parse the request
                    String[] tokens = request.split(" ");
                    String appName = tokens[1];
                    String dateTimeStamp = tokens[2];
                    String platform = tokens[3];
                    String problemDesc = tokens[4];
                    String status = tokens[5];

                    // Add the bug report to the database
                    int bugId = nextBugId++;
                    bugDatabase.put(bugId, appName + " " + dateTimeStamp + " " + platform + " " + problemDesc + " " + status);
                    outToClient.writeBytes("OK " + bugId + "\n");
                }
                else if (request.startsWith("UPDATE"))
                {
                    // Parse the request
                    String[] tokens = request.split(" ");
                    int bugId = Integer.parseInt(tokens[1]);
                    String newStatus = tokens[2];

                    // Update the bug report in the database
                    if (updateBugStatus(bugId, newStatus))
                    {
                        outToClient.writeBytes("OK\n");
                    }
                    else
                    {
                        outToClient.writeBytes("ERROR: Invalid bug ID\n");
                    }
                }
                else if (request.startsWith("VIEW"))
                {
                    // Send all the bug reports to the client
                    for (int bugId : bugDatabase.keySet())
                    {
                        outToClient.writeBytes(bugId + " " + bugDatabase.get(bugId) + "\n");
                    }
                    outToClient.writeBytes("OK\n");
                }
                else if (request.startsWith("QUIT"))
                {
                    // Close the connection to the client
                    connectionSocket.close();
                }
                else
                {
                    // Print an error message if the request is invalid
                    outToClient.writeBytes("ERROR: Invalid request\n");
                }
            }
            catch (IOException ex)
            {
                System.out.println("Error: An I/O exception occurred");
            }
        }        // Helper method to update the status of a bug report in the database
        private boolean updateBugStatus(int bugId, String newStatus)
        {
            if (!bugDatabase.containsKey(bugId))
            {
                return false;
            }

            String[] bugDetails = bugDatabase.get(bugId).split(" ");
            bugDetails[4] = newStatus;
            bugDatabase.put(bugId, String.join(" ", bugDetails));
            return true;
        }
    }
}                           

import java.io.*;
import java.net.*;
import java.util.*;

public class Client
{
    public static void main(String[] args)
    {
        try
        {
            // Create a socket to connect to the server
            Socket clientSocket = new Socket("localhost", 6789);

            // Create input and output streams to read from and write to the server
            BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());

            // Read input from the user
            BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));

            while (true)
            {
                // Print a prompt to the user
                System.out.print("Enter a command (REGISTER, LOGIN, or QUIT): ");

                // Read the command from the user
                String command = userInput.readLine();

                if (command.equals("REGISTER"))
                {
                    // Read the username and password from the user
                    System.out.print("Enter a username: ");
                    String username = userInput.readLine();
                    System.out.print("Enter a password: ");
                    String password = userInput.readLine();

                    // Send the REGISTER command and the username and password to the server
                    outToServer.writeBytes("REGISTER " + username + " " + password + "\n");

                    // Read the response from the server
                    String response = inFromServer.readLine();
                    System.out.println(response);
                }
                else if (command.equals("LOGIN"))
                {
                    // Read the username and password from the user
                    System.out.print("Enter a username: ");
                    String username = userInput.readLine();
                    System.out.print("Enter a password: ");
                    String password = userInput.readLine();

                    // Send the LOGIN command and the username and password to the server
                    outToServer.writeBytes("LOGIN " + username + " " + password + "\n");

                    // Read the response from the server
                    String response = inFromServer.readLine();
                    System.out.println(response);

                    // If the login was successful, allow the user to add a bug report
                    if (response.equals("OK"))
                    {
                        while (true)
                        {
                            // Print a prompt to the user
                            System.out.print("Enter a command (ADD, UPDATE,VIEW ,or QUIT): ");

                            // Read the command from the user
                            String command2 = userInput.readLine();

                            if (command2.equals("ADD"))
                            {
                                // Read the bug report details from the user
                                System.out.print("Enter the application name: ");
                                String appName = userInput.readLine();
                                System.out.print("Enter the date and time stamp: ");
                                String dateTime = userInput.readLine();
                                System.out.print("Enter the platform: ");
                                String platform = userInput.readLine();
                                System.out.print("Enter the problem description: ");
                                String problem = userInput.readLine();
                                System.out.print("Enter the status (Open, Assigned, or Closed): ");
                                String status = userInput.readLine();

                                // Send the ADD command and the bug report details to the server
                                outToServer.writeBytes("ADD " + appName + " " + dateTime + " " + platform + " " + problem + " " + status + "\n");

                                // Read the response from the server
                                String response2 = inFromServer.readLine();
                                System.out.println(response2);
                            }
                            else if (command2.equals("UPDATE"))
                            {
                                // Read the bug report ID and new status from the user
                                System.out.print("Enter the bug report ID: ");
                                int bugId = Integer.parseInt(userInput.readLine());
                                System.out.print("Enter the new status (Open, Assigned, or Closed): ");
                                String newStatus = userInput.readLine();

                                // Send the UPDATE command and the bug report ID and new status to the server
                                outToServer.writeBytes("UPDATE " + bugId + " " + newStatus + "\n");

                                // Read the response from the server
                                String updateResponse = inFromServer.readLine();
                                System.out.println(updateResponse);
                            }
                            else if (command2.equals("VIEW"))
                            {
                                // Send the VIEW command to the server
                                outToServer.writeBytes("VIEW\n");

                                // Read the response from the server
                                String response2 = inFromServer.readLine();

                                // Print the bug reports received from the server
                                while (!response2.equals("OK"))
                                {
                                    System.out.println(response2);
                                    response2 = inFromServer.readLine();
                                }
                            }
                            else if (command2.equals("QUIT"))
                            {
                                // Send the QUIT command to the server
                                outToServer.writeBytes("QUIT\n");

                                // Close the connection to the server
                                clientSocket.close();

                                // Terminate the loop
                                break;
                            }
                            else
                            {
                                // Print an error message if the command is invalid
                                System.out.println("Invalid command");
                            }
                        }
                    }
                }
                else if (command.equals("QUIT"))
                {
                    // Send the QUIT command to the server
                    outToServer.writeBytes("QUIT\n");

                    // Close the connection to the server
                    clientSocket.close();

                    // Terminate the loop
                    break;
                }
                else
                {
                    // Print an error message if the command is invalid
                    System.out.println("Invalid command");
                }
            }
        }
        catch (UnknownHostException ex)
        {
            System.out.println("Error: Unable to connect to the server");
        }
        catch (IOException ex)
        {
            System.out.println("Error: An I/O exception occurred");
        }
        catch (NumberFormatException ex)
        {
            System.out.println("Error: Invalid input");
        }
    }
}

I just want to simply make it so that the bugs are registered to the server and then can be show on the client side without anything crashing

the execption thrown:

Exception in thread "main" java.net.SocketException: An established connection was aborted by the software in your host machine
    at java.base/sun.nio.ch.NioSocketImpl.implWrite(NioSocketImpl.java:420)
    at java.base/sun.nio.ch.NioSocketImpl.write(NioSocketImpl.java:440)
    at java.base/sun.nio.ch.NioSocketImpl$2.write(NioSocketImpl.java:826)
    at java.base/java.net.Socket$SocketOutputStream.write(Socket.java:1035)
    at java.base/java.net.Socket$SocketOutputStream.write(Socket.java:1031)
    at java.base/java.io.DataOutputStream.writeBytes(DataOutputStream.java:282)
    at Client.main(Client.java:83)

Answer 1

The "An established connection was aborted by the software in your host machine" exception is the client noticing the server process has crashed and closed the connection, while writing at Client.java:83.

It would be more helpful to see crash information from the Server process where the defect appears to occur. However even without that, I notice you are using a space-delimited protocol, ie:

Client:

// Send the ADD command and the bug report details to the server
outToServer.writeBytes("ADD " + appName + " " + dateTime + " " + platform + " " + problem + " " + status + "\n");

Server:

 else if (request.startsWith("ADD"))
 {
     // Parse the request
     String[] tokens = request.split(" ");
     String appName = tokens[1];
     String dateTimeStamp = tokens[2];
     String platform = tokens[3];
     String problemDesc = tokens[4];
     String status = tokens[5];

     // Add the bug report to the database
     int bugId = nextBugId++;
     bugDatabase.put(bugId, appName + " " + dateTimeStamp + " " + platform + " " + problemDesc + " " + status);
     outToClient.writeBytes("OK " + bugId + "\n");

However this probably only functions as you intend if none of those fields includes an embedded space character, If they do, then it throws off the server parsing of the fields. and the trailing words in your new record will be truncated. The same assumption/problem occurs elsewhere in the server code.

I'm not sure why this would cause an actual crash, but you should probably choose a better delimiter character that is less likely to appear embedded in the field values.