利用java语言提供的socket技术，建立一个c/s模式的应用，允许客户端用户输入2个整数，服务器端接收这2个整数，并计算出它们的和、差、积、商，最后送回客户端。

这个应用可以通过以下步骤实现：

1. 客户端连接服务器端的socket，发送2个整数给服务器端。

2. 服务器端接收这2个整数，并进行计算。

3. 服务器端将计算结果发送回客户端。

4. 客户端接收服务器端发送的计算结果。

具体实现可以参考以下代码：

服务器端：

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

public class Server {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(8888);
        System.out.println("服务器已启动，等待客户端连接...");

        while (true) {
            Socket socket = serverSocket.accept();
            System.out.println("客户端已连接：" + socket.getInetAddress().getHostAddress());

            BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            int num1 = Integer.parseInt(reader.readLine());
            int num2 = Integer.parseInt(reader.readLine());

            int sum = num1 + num2;
            int diff = num1 - num2;
            int product = num1 * num2;
            int quotient = num1 / num2;

            PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);
            writer.println("和：" + sum);
            writer.println("差：" + diff);
            writer.println("积：" + product);
            writer.println("商：" + quotient);

            socket.close();
        }
    }
}

客户端：

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

public class Client {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("localhost", 8888);
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);

        System.out.print("请输入第一个整数：");
        int num1 = Integer.parseInt(reader.readLine());
        writer.println(num1);

        System.out.print("请输入第二个整数：");
        int num2 = Integer.parseInt(reader.readLine());
        writer.println(num2);

        BufferedReader serverReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        System.out.println("计算结果：");
        System.out.println(serverReader.readLine());
        System.out.println(serverReader.readLine());
        System.out.println(serverReader.readLine());
        System.out.println(serverReader.readLine());

        socket.close();
    }
}