由于什么原因，RequestDispatcher.forward（）方法返回到调用的servlet？如果我们不能做出响应更改，返回的用途是什么？

Question

我只想了解在执行转发的servlet之后返回到调用servlet的目的。

下面的示例仅显示在执行转发的servlet之后，控制权返回到调用servlet。

//servlet1 Code (Forwarding to servlet2)   
@WebServlet("/servlet1")
public class Login extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

      RequestDispatcher rd = request.getRequestDispatcher("servlet2");
      rd.forward(request, response);

      System.out.println("Returned to Calling Servlet");
   }
}

//servlet2 Code (returning control to servlet1)  
@WebServlet("/servlet2")
public class WelcomeServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    response.setContentType("text/html");
    PrintWriter out = response.getWriter();

    String n = "to Servlet2";
    out.print("Welcome " + n);
   }
}

输出::

欢迎使用Servlet2（在浏览器上）

返回到调用Servlet（在控制台上）

需要澄清：

提交响应后，为何返回到 servlet1