这是神马情况？？

[舞黯然]

竟然报错说c:out标签的value属性不支持表达式？？who can tell me why？？

<%@ page contentType="text/html;charset=utf-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
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<c:out value="${sample.userName}" />

org.apache.jasper.JasperException: /success.jsp(4,0) According to TLD or attribute directive in tag file, attribute value does not accept any expressions
	org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:40)
	org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:407)
	org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:148)
	org.apache.jasper.compiler.Validator$ValidateVisitor.checkXmlAttributes(Validator.java:1213)
	org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:852)
	org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1530)
	org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2361)
	org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2411)
	org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2417)
	org.apache.jasper.compiler.Node$Root.accept(Node.java:495)
	org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2361)
	org.apache.jasper.compiler.Validator.validateExDirectives(Validator.java:1775)
	org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:183)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:332)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:312)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:299)
	org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:589)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:236)
	org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:257)
	org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1183)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:902)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:807)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:571)
	org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:511)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

[小武茶庄]

你的神马标签定义错了呗！
您定义的所谓神马标签是jsf标签。
jsp标签定义为:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

[舞黯然]

万分感谢！