5．参考代码代码仅供参考，学生可按着实验要求，参考本代码编写代码。JSP页面参考代码inputNumber.jsp<%@ page contentType="text/html;charset=GB2312" %><%@ taglib tagdir="/WEB-INF/tags" prefix="computer"%>
输入运算数、选择运算符号:<input size="6" name="numberOne" type="text" /> + - * / <input size="6" name="numberTwo" type="text" />
<input value="提交你的选择" type="submit" /> <% String a=request.getParameter("numberOne"); String b=request.getParameter("numberTwo"); String operator=request.getParameter("operator"); if(a==null||b==null) { a=""; b=""; } if(a.length()>0&&b.length()>0) { %> <computer:Computer numberA="<%=a%>" numberB="<%=b%>" operator="<%=operator%>"/> 计算结果：<%=a%><%=operator%><%=b%>=<%=result%><% }%>Tag文件参考代码Computer.Tag<%@ tag pageEncoding="gb2312"%> <%@ attribute name="numberA" required="true" %> <%@ attribute name="numberB" required="true" %><%@ attribute name="operator" required="true" %><%@ variable name-given="result" scope="AT_END" %><% try { double a=Double.parseDouble(numberA); double b=Double.parseDouble(numberB); double r=0; if(operator.equals("+")) { r=a+b; } else if(operator.equals("-")) { r=a-b; } else if(operator.equals("*")) { r=a*b; } else if(operator.equals("/")) { r=a/b; } jspContext.setAttribute("result",String.valueOf(r)); } catch(Exception e) { jspContext.setAttribute("result","发生异常:"+e); }%>
