java使用多线程编程，实现socket服务器客户端交互

自己写用来练习的小例子，大神请绕道

package cs;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * 使用多线程编程，实现客户端发送长和宽，服务器接收参数并传回面积
 */
public class Test
{
    public static void main(String[] args)
    {
        Thread server = new Thread(new Server());
        server.start();
        Thread client = new Thread(new Client());
        client.start();
    }
}

class Server implements Runnable
{

    @Override
    public void run()
    {
        ServerSocket serverSocket = null;
        Socket socket = null;
        PrintWriter writer = null;
        BufferedReader reader = null;
        try
        {
            serverSocket = new ServerSocket(2000);
            socket = serverSocket.accept();

            reader = new BufferedReader(new InputStreamReader(
                    socket.getInputStream()));
            String str = reader.readLine();
            String result = handle(str);
            writer = new PrintWriter(socket.getOutputStream());
            writer.println(result);
            writer.flush();
        }
        catch (IOException e)
        {
            System.out.println(e);
        }
    }

    private String handle(String str)
    {
        String param[] = str.split(",");
        int x = Integer.valueOf(param[0]);
        int y = Integer.valueOf(param[1]);
        System.out.println("Server : revice param:" + str);
        return x * y + "";
    }
}

class Client implements Runnable
{

    @Override
    public void run()
    {
        Socket socket = null;
        PrintWriter writer = null;
        BufferedReader reader = null;
        try
        {
            socket = new Socket("127.0.0.1", 2000);
            writer = new PrintWriter(socket.getOutputStream());

            reader = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("请输入长：");
            String x = reader.readLine();
            System.out.println("请输入宽：");
            String y = reader.readLine();
            String param = x + "," + y;
            writer.println(param);
            writer.flush();
            reader = new BufferedReader(new InputStreamReader(
                    socket.getInputStream()));
            System.out.println("Client : result from server:"
                    + reader.readLine());
        }
        catch (IOException e)
        {
            System.out.println(e);
        }
    }
}