简单的Java多线程套接字应用程序

Question

I have this simple multi-threaded java socket application. Using classes Client.java

public class Client {

private static Socket socket;
private static boolean waitForServer = false;
public static void main(String[] args) throws IOException {
    while(true){
        socket = new Socket("localhost", ServerPortInfo.getPort());
        PrintWriter printWriter = new PrintWriter(socket.getOutputStream(), true);
        BufferedReader bufferedReader = new java.io.BufferedReader(new InputStreamReader(System.in));

        while(true){
            PrintWriter.println(name + " Hello");
                waitForServer = true;

            if (waitForServer){
                BufferedReader inputBufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                String inputString = null;
                while((inputString = inputBufferedReader.readLine()) != null){
                    System.out.println(inputString);
                    break;
                }

            }

        }

    }
  }
}

And Server.java

public class Server {

public static ArrayList<ServerThread> connections = new ArrayList<ServerThread>();

public static void main(String[] args) throws IOException, SQLException, ClassNotFoundException {
    // Init server functionality
    new Server().runServer();


}

// Implementing server functionality
public void runServer() throws IOException{

    ServerSocket serverSocket = new ServerSocket(ServerPortInfo.getPort());
    System.out.println("Server is running... Waiting for connections");
    while (true){
        Socket socket = serverSocket.accept();
        // After connection handle clients in threads
        ServerThread newThread = new ServerThread(socket);
        connections.add(newThread);
        newThread.start();
    }

}
}

And then a Thread that handles that connection...

public class ServerThread extends Thread {

private static Socket socket;
public static boolean alive = true;

ServerThread(Socket socket){
    this.socket = socket;
}

public void run(){
    if (alive) {
        //DO STUFF NOW
}       

}

And now when I have multiple connections. It creates a different Thread for every connection. What should i do when a user wants to disconnect from this server?

Should i kill the thread, socket?

I tried just saying to the thread alive = false; so the run would just stop running. But this breaks other connections as well.

EDIT

ServerThread ->

private Socket socket;

And a function ->

void closeConnection() throws IOException{
    this.socket.close();
}

works like a charm.

Answer 1

public static variables are a recipe for disaster (as I'm sure you've just found out the hard way). But as @cktang said, close the socket, then kill that thread (not the others). -@JoeC

Changed private static Socket socket; to private Socket socket; . Closed the socket and then Thread.

Answer 2

The problem is with

public static boolean alive = true;
private static Socket socket;

As it is static, it influences all your ServerThread 's, but each ServerThread (aka connected client) should have its own socket and flag indicating if it's alive or not.

Remove the static modifier from both attributes and make the flag
private volatile boolean alive = true;

At first close the socket a then stop the thread (and remove it from the list).