用jsp中做一个登录页面，用request对象设计实现一个简单的计算加减乘除运算的网页程序

可以使用jsp中的表单和servlet来实现计算加减乘除运算的网页程序。首先，在jsp页面中创建一个表单，包括运算符和两个操作数的输入框。设置提交按钮的action为一个处理表单数据的servlet。在servlet中，使用request对象获取表单提交的数据，进行相应的运算，并将结果存储在request对象中，然后转发给显示结果的jsp页面。具体实现可以参考以下代码：

login.jsp:

<form action="calculate" method="post">
  Operand 1: <input type="text" name="operand1"><br>
  Operand 2: <input type="text" name="operand2"><br>
  Operator:
  <select name="operator">
    <option value="+">+</option>
    <option value="-">-</option>
    <option value="*">*</option>
    <option value="/">/</option>
  </select><br>
  <input type="submit" value="Submit">
</form>

CalculateServlet.java:

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CalculateServlet extends HttpServlet {
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    int operand1 = Integer.parseInt(request.getParameter("operand1"));
    int operand2 = Integer.parseInt(request.getParameter("operand2"));
    String operator = request.getParameter("operator");
    int result = 0;
    if (operator.equals("+")) {
      result = operand1 + operand2;
    } else if (operator.equals("-")) {
      result = operand1 - operand2;
    } else if (operator.equals("*")) {
      result = operand1 * operand2;
    } else if (operator.equals("/")) {
      result = operand1 / operand2;
    }
    request.setAttribute("result", result);
    request.getRequestDispatcher("result.jsp").forward(request, response);
  }
}

result.jsp:

Result: <%= request.getAttribute("result") %>