代码解释基本都在代码中给出
1 <%@ page language="java" contentType="text/html; charset=UTF-8"
2 pageEncoding="UTF-8"%>
3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
4 <html>
5 <head>
6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
7 <title>简易计算器</title>
8 </head>
9 <body>
10
11 <!--
12 总结一下今天学到的知识
13 1、学到了EL表达式----》贼强哇 以前都不知道（调用的时候直接写&{里边写下边4中的一种之后添加东西}
14 ①：PageScope
15 ②：RequestScope
16 ③：SessionScope
17 ④：ApplicationScope
18 2、说一下自己在写完代码与看完老师代码之后出现的一些复杂的地方
19 ①：我在处理radio的时候使用for循环写的 但是，看了老师的三元表达式以后，我承认，我的复杂了 （无懈可击）
20 3、今天还学到了一个新知识（关于服务器跳转和客户端跳转）
21 ①：服务器跳转（快）：在服务器之间跳转是可以使用request的
22 ②：客户端跳转（相对于服务器 不快）：在客户端跳转中是应该使用session的
23 -->
24 <form action="CalServlet" method="post" name="From" >
25 第一个数：<input type="text" name="num1" value="${requestScope.cal.num1}"><br>
26 运算符：
27 <input type="radio" name="operator" value="+" ${requestScope.cal.op=="+"?"checked":""}>+
28 <input type="radio" name="operator" value="-" ${requestScope.cal.op=="-"?"checked":""}>-
29 <input type="radio" name="operator" value="*" ${requestScope.cal.op=="*"?"checked":""}>*
30 <input type="radio" name="operator" value="/" ${requestScope.cal.op=="/"?"checked":""}>/
31 <br>
32 第二个数：<input type="text" name="num2" value="${requestScope.cal.num2}"><br>
33 <input type="submit" name="smt" value="提交"><br>
34 计算结果：<input type="text" name="result" value="${result}">
35 </form>
36
37 </body>
38 </html>
Jsp页面
package Calculation;
public class Cal {
private float num1;
private String op;
private float num2;
public float getNum1() {
return num1;
}
public void setNum1(float num1) {
this.num1 = num1;
}
public String getOp() {
return op;
}
public void setOp(String op) {
this.op = op;
}
public float getNum2() {
return num2;
}
public void setNum2(float num2) {
this.num2 = num2;
}
}
JvaBean代码
1 package CalculationServlet;
2
3 import java.io.IOException;
4 import javax.servlet.ServletException;
5 import javax.servlet.annotation.WebServlet;
6 import javax.servlet.http.HttpServlet;
7 import javax.servlet.http.HttpServletRequest;
8 import javax.servlet.http.HttpServletResponse;
9
10 import Calculation.Cal;
11
12 /**
13 * Servlet implementation class CalServlet
14 */
15 @WebServlet("/CalServlet")
16 public class CalServlet extends HttpServlet {
17 private static final long serialVersionUID = 1L;
18
19 /**
20 * @see HttpServlet#HttpServlet()
21 */
22 public CalServlet() {
23 super();
24 // TODO Auto-generated constructor stub
25 }
26
27 /**
28 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
29 */
30 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
31 // TODO Auto-generated method stub
32 response.getWriter().append("Served at: ").append(request.getContextPath());
33 }
34
35 /**
36 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
37 */
38 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
39 // TODO Auto-generated method stub
40 //doGet(request, response);
41 response.setCharacterEncoding("UTF-8");
42 Cal cal = new Cal();
43 cal.setNum1(Float.parseFloat(request.getParameter("num1")));
44 cal.setOp(request.getParameter("operator"));
45 cal.setNum2(Float.parseFloat(request.getParameter("num2")));
46 float result = 0;
47 switch(cal.getOp().charAt(0)) {
48 case ‘+‘: result = cal.getNum1() + cal.getNum2();break;
49 case ‘-‘: result = cal.getNum1() - cal.getNum2();break;
50 case ‘*‘: result = cal.getNum1() * cal.getNum2();break;
51 case ‘/‘: result = cal.getNum1() / cal.getNum2();break;
52 //可以加入一个default
53 }
54 //System.out.println(result);
55 request.setAttribute("result", result);
56 request.setAttribute("cal", cal); //---- 传值不过去？？？
57 //request.getSession().setAttribute("cal", cal);
58 //新知识
59 //下边的这个函数就是服务器之间跳转 注意需要先调用getRequestDispatcher来获取这个对象 我是这么理解的
60 request.getRequestDispatcher("Cal.jsp").forward(request, response);
61 }
62
63 }
Servlet代码
原文地址：https://www.cnblogs.com/Yinchen-One/p/9629583.html
时间： 2024-08-04 12:43:22