代码解释基本都在代码中给出
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2pageEncoding="UTF-8"%> 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "/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：PageScope15 ②：RequestScope16 ③：SessionScope17 ④：ApplicationScope18 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 CalServlet14 */15 @WebServlet("/CalServlet")16 public class CalServlet extends HttpServlet {17private static final long serialVersionUID = 1L;18 19/**20* @see HttpServlet#HttpServlet()21*/22public CalServlet() {23 super();24 // TODO Auto-generated constructor stub25}26 27/**28* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)29*/30protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {31 // TODO Auto-generated method stub32 response.getWriter().append("Served at: ").append(request.getContextPath());33}34 35/**36* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)37*/38protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {39 // TODO Auto-generated method stub40 //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default53 }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
下边大概了解一下过滤器的问题
//个人理解
1、重要内容写在doFilter中
2、传值那些的写在doinit中
