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需求说明：
// index.jsp页面
1 <%
2 String basePath = request.getScheme()+":"+"//"+request.getServerName()+":"+request.getServerPort()+"/"
3 +request.getServletContext().getContextPath()+"/";
4 %>
5 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
6 <html>
7 <head>
8 <title>ServletDemo加法运算</title>
9 </head>
10 <body>
11 <%--action: 表示访问的servlet路径--%>
12 <%out.print("basePath意味着：" + basePath);%>
13 <form action="<%=basePath%>ServletDemo1" method="post">
14 a: <input type="text" name="a"><br>
15 b: <input type="text" name="b"><br>
16 <input type="submit" value="计算"/><br>
17 </form>
18 </body>
19 </html>
// ServletDemo1.java
1 import javax.servlet.ServletContext;
2 import javax.servlet.ServletException;
3 import javax.servlet.annotation.WebServlet;
4 import javax.servlet.http.HttpServlet;
5 import javax.servlet.http.HttpServletRequest;
6 import javax.servlet.http.HttpServletResponse;
7 import java.io.IOException;
8
9 @WebServlet("/ServletDemo1")
10 public class ServletDemo1 extends HttpServlet {
11 @Override
12 public void init() throws ServletException {
13 System.out.println("init()方法");
14 }
15
16 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
17 System.out.println("doPost()方法");
18 doGet(request, response);
19 }
20
21 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
22 String a = request.getParameter("a");
23 String b = request.getParameter("b");
24 int sum = Integer.valueOf(a) + Integer.valueOf(b);
25 request.setAttribute("sum", sum);
26 // 方式一：PrintWriter对象写入
27 // response.getWriter().print(sum);
28 // 方式二：请求转发
29 // request.getRequestDispatcher("sum.jsp").forward(request, response);
30 // 方式三：重定向
31 ServletContext sc = request.getServletContext();
32 sc.setAttribute("sum2", sum);
33 response.sendRedirect("sum2.jsp");
34 System.out.println("doGet()方法");
35 }
36
37 @Override
38 public void destroy() {
39 System.out.println("destroy()方法");
40 }
41 }
// sum.jsp页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>请求跳转求和</title></head><body>a + b = <%=request.getAttribute("sum")%></body></html>
// sum2.jsp页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head> <title>重定向跳转求和</title></head><body>a + b = <%=application.getAttribute("sum2")%></body></html>
index.jsp页面效果图展示：
1. 方式一：PrintWriter对象写入效果图：
2. 方式二：请求转发效果图：
3. 重定向效果图：
原文地址：https://www.cnblogs.com/chris0710/p/8970543.html
时间： 2024-08-27 17:36:38