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>
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; } }
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 }
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