如果线程发送信号，则更改应用程序行为

Question

我写了这个简单的代码：

class main{
public static void main(String []a)throws UnknownHostException,IOException{
    Scanner sc = new Scanner(System.in);
    int choice;
    ServerSocket ss = new ServerSocket(60000,1,InetAddress.getLocalHost());
    Thread t = new Thread(new Conversation(ss));
    t.start();
    while(true){// I think i need to set a better condition here
        do{
            System.out.println("Hello user choose a number between 0 and 2");
        }
        while(!sc.hasNextInt());
        choice = sc.nextInt();
        if(choice >2 || choice < 0)
            choice = 0;
        switch(choice){
            case 0:
            //print some stuff
            break;
            case 1:
            //print other stuff
            break;
            case 2:
            //print new stuff
            break;
            default:
            break;
        }
    }
}

}

下面是 Conversation 类的代码：

public class Conversation implements Runnable {
ServerSocket ss;
Socket client;
boolean connected;
Conversation(ServerSocket cli){
    this.ss= cli;
    client = null;
    connected = false;
}
void connected(){
    this.connected = true;
}
void disconnected(){
    this.connected = false;
}
@Override
public void run() {
    // TODO Auto-generated method stub
    while(true) {
        PrintWriter pw = null;
        if(!this.connected){
            try {
                client = ss.accept();
                pw =new PrintWriter(client.getOutputStream(),true);
                this.connected();
            } catch (IOException e) {
                System.err.println("Accept failed.");
                System.err.println(e);
                System.exit(1);
            }
            BufferedReader in = null;
            PrintWriter out = null;
            try {
                in = new BufferedReader(new InputStreamReader(
                    client.getInputStream()));
                out = new PrintWriter(client.getOutputStream(), true);
            } catch (IOException e) {
                System.err.println(e);
                return;
            }

            String msg;
            try {
                while ((msg = in.readLine()) != null) {
                    if(msg.equals("CLO") || msg.equals("clo")){// if a CLO message is sent the conversation ends
                        client.close();
                        in.close();
                        out.close();
                        pw.close();
                        this.disconnected();
                        break;
                    }
                    else{
                        System.out.println("Client says: " + msg.substring(7));
                    }
                }
            } catch (IOException e) {
                System.err.println(e);
            }
        }
    }
}

}

基本上，它所做的只是等待用户输入，然后根据他输入的内容打印一些内容。 我面临的问题是： 我希望当有人在线程 t 中连接到 ServerSocket ss 时（所以 connected 的值为 true）我希望 main 函数停止它正在做的任何事情，并将用户输入发送到套接字客户端的 OutputStream 中（所以换句话说，当有人连接到 ServerSocket 时开始聊天）。 但我不知道该怎么做，我是 Java 中的线程和网络的新手，线程 T 有没有办法向主类的主函数发送信号，或者有人知道如何实现这个？

Answer 1

我已经在相同的上下文中发布了一些示例代码。请查看以下示例，并尝试按照每一步来理解它。仔细阅读内联 cmets。

• Multiple clients access the server concurrently

• Java Server with Multiclient communication.

• Server-Client chat program

如果有任何混淆，请告诉我。