java更改bg颜色jsp
关于这件事。当我运行代码时，我在表达式中得到一个错误：
org.apache.jasper.JasperException: An exception
occurred processing JSP page [/apps.jsp] at line [15]
12: <input type="button" name="red" value ="red" >
13: <%
14: String button1Click = request.getParameter("red");
15: if(button1Click.equals("red")){
16: %>
17: <body style='background-color: red;'>
18: <%
我该怎么修？所有代码
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action = "apps" method="POST">
<input type="button" name="red" value ="red" >
<%
String button1Click = request.getParameter("red");
if(button1Click.equals("red")){
%>
<body style='background-color: red;'>
<%
}
%>
<input type="submit" name="blue" value ="blue" >
<input type="submit" name="green" value ="green" >
<input type="submit" name="yellow" value ="yellow" >
<input type="submit" name="reset" value ="reset" >
</form>
</form>
</body>
</html>
# 1 楼答案
这可能是因为
NullPointerException。试试看用整个java代码替换
<body>标记之后的</header>标记# 2 楼答案
您正在jsp页面中使用java代码。Jave代码总是先执行。这样你的颜色就不会因为点击按钮而改变