使用JavaSocket和ServerSocket创建计算器服务

我尝试用Java的ServerSocket和Socket类创建一个基本服务器。其思想是，客户端必须向服务器发送一个号码和一个操作，服务器只需返回结果。到目前为止，我已经完成了以下代码：

对于客户：

package clientepm;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;

class Stub {

    Socket s;
    ObjectInputStream ois;
    ObjectOutputStream oos;

    Stub(){
        try {
            s = new Socket("localhost", 50000);
            oos = new ObjectOutputStream(s.getOutputStream());         
            ois = new ObjectInputStream(s.getInputStream());
        } catch (IOException ex) {
            Logger.getLogger(Stub.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public double calculate(char op, int num){

        try {
            oos.writeChar(op);
            oos.writeInt(num);
            double ret = ois.readDouble();
            s.close();
            ois.close();
            oos.close();
            return ret;
        } catch (IOException ex) {
            Logger.getLogger(Stub.class.getName()).log(Level.SEVERE, null, ex);
        }
        return -1;

    }

}

package clientepm;

import java.util.logging.Level;
import java.util.logging.Logger;

public class Client extends Thread {

    Stub s;

    Client(Stub s){
        this.s = s;
    }

    @Override
    public void run(){
        int[] numbers = {12,23,35,43,55};
        char[] ops = {'M','M','Q','Q','M'};
        for (int i=0;i<5;i++){
            double result = s.calculate(ops[i], numbers[i]);
            System.out.println("Received Value " + result);
        }


    }

}



package clientepm;

public class TestClient {

    public static void main(String[] args){
        Stub b = new Stub();
        new Client(b).start();
    }

}

如您所见，当操作为“M”时，服务器应乘以x10，当操作为“Q”时，服务器应将数字平方。但是，代码不起作用

---

有人能帮我吗？

你能详细说明一下“不起作用”吗？你有例外吗？程序只是冻结了，什么也没有打印。你能详细说明一下“不起作用”吗？你有例外吗？程序只是冻结了，没有打印任何内容。

package servidorpm;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Skel extends Thread {

    Socket s;
    ObjectInputStream ois;
    ObjectOutputStream oos;

    Skel(Socket s){
        try {
            this.s=s;
            oos = new ObjectOutputStream(s.getOutputStream());
            ois = new ObjectInputStream(s.getInputStream());
        } catch (IOException ex) {
            Logger.getLogger(Skel.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public void run(){
        while(true){
            try {
                char op = ois.readChar();
                int num = ois.readInt();
                switch(op){
                    case 'M':
                        oos.writeDouble(num*10);
                        break;
                    case 'Q':
                        oos.writeDouble(num*num);
                        break;
                    default:
                        System.out.println("Error");
                        break;
                }

            } catch (Exception ex) {
                System.out.println("Exception");
                Logger.getLogger(Skel.class.getName()).log(Level.SEVERE, null, ex);
            }

        }

    }

}

package servidorpm;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ServerTest {

    public static void main(String[] args) {
        try {
            ServerSocket ss = new ServerSocket(50000);
            while (true) {
                Socket s = ss.accept();
                new Skel(s).start();
            }
        } catch (IOException ex) {
            Logger.getLogger(ServerTest.class.getName()).log(Level.SEVERE, null, ex);
        }

    }

}