一个关于JSTL和EL的问题
为什么我这样<c:out value="${myForm.username}"></c:out>组合用就会报：
javax.servlet.ServletException: org.apache.jasper.JasperException: /success.jsp(12,0) According to TLD or attribute directive in tag file, attribute value does not accept any expressions
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)


root cause 

org.apache.jasper.JasperException: /success.jsp(12,0) 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$ValidateVisitor.checkXmlAttributes(Validator.java:1172)
org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:819)
org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1507)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2336)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2386)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2392)
org.apache.jasper.compiler.Node$Root.accept(Node.java:489)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2336)
org.apache.jasper.compiler.Validator.validate(Validator.java:1737)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:178)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:306)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:286)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:273)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:566)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.struts.chain.commands.servlet.PerformForward.handleAsForward(PerformForward.java:113)
org.apache.struts.chain.commands.servlet.PerformForward.perform(PerformForward.java:96)
org.apache.struts.chain.commands.AbstractPerformForward.execute(AbstractPerformForward.java:54)
org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

的错误？
但是分开用都是可以输出我要打印的东西的，组合起就不行了，这是为什么啊？

------解决方案--------------------
貌似是标签版本问题
------解决方案--------------------
貌似是标签版本问题
------解决方案--------------------
引用最新的jstl的标签声明
------解决方案--------------------
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>