Java项目案例之---加法计算器（转发和重定向）

加法计算器（转发和重定向）

运行显示：

重定向

代码：

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2019/7/22 0022
  Time: 下午 5:51
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<form action="CountServlet" method="post">
    <h3>加法计算器</h3>
    加数1：<input type="number" name="one">
    加数2：<input type="number" name="two">
    <input type="submit" value="计算">
</form>
</body>
</html>

count.jsp

<%--

  Created by IntelliJ IDEA.

  User: Administrator

  Date: 2019/7/22 0022

  Time: 下午 5:51

  To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

</head>

<body>

计算结果：<%=request.getAttribute("count")%>

<!--计算结果：<%=application.getAttribute("count")%>-->

</body>

</html>

package servlet;



import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;



@WebServlet("/CountServlet")

public class CountServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {



         String one=request.getParameter("one");

         int o=Integer.parseInt(one);//强制转换，将String类型的数据转换成int类型

         String two=request.getParameter("two");

         int t=Integer.parseInt(two);//强制转换，将String类型的数据转换成int类型

         System.out.println(one+"   "+two);

         int c=o+t;

         String co=String.valueOf(c);//将int类型的数据转换成String类型

         //转发，可以携带数据

         request.setAttribute("count",co);

         request.getRequestDispatcher("count.jsp").forward(request,response);

        //用于存放数据

//        ServletContext s=this.getServletContext();

//        s.setAttribute("count",co);

        //重定向只能依靠ServletContext获取数据

//        response.sendRedirect("count.jsp");

         System.out.println(co);

    }



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

         doPost(request,response);

    }

}