如何激活HttpServlet类?

我有一个扩展到HttpServlet类的类。

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class GreetServer extends HttpServlet {
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.getWriter().print("hello client");
}
// Method to handle POST method request.
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}

我的问题是，我如何使它工作和处理POST和GET请求(我应该在我的public static void main(String[] args)方法中写什么)?我正在使用Heroku来部署应用程序。谢谢。