<%@ page contentType="text/html; Charset=gb2312" %> <%@ taglib tagdir="/WEB-INF/tags" prefix="computer" %> <html> <head> <title>JSP练习</title> </head> <body> <h3>以下是调用TAG文件的效果:</h3> <computer:Trangle sideA="3" sideB="4" sideC="5"/> </body> </html>
Trangle.tag
<p>这是一个TAG文件，负责计算三解角形的面积</p>
<%@ attribute name="sideA" required="true"%>
<%@ attribute name="sideB" required="true"%>
<%@ attribute name="sideC" required="true"%>
<%!
public String getArea(double a, double b, double c){
if (a + b > c && a + c > b && b + c > a){
double p = (a + b + c) / 2.0;
double area = Math.sqrt(p * (p - a) *
(p - b) * (p - c));
return "<br>三角形的面积：" + area;
}
else{
return "<br>" + a + "," + b + "," + c +
"不能构成一个三角形，无法计算面积";
}
}
%>
<%
out.println("<br>JSP页面传递过来的三条边：" + sideA + "," +
sideB + "," + sideC);
double a = Double.parseDouble(sideA);
double b = Double.parseDouble(sideB);
double c = Double.parseDouble(sideC);
out.println(getArea(a, b, c));
%>
