【发布时间】：2018-05-25 06:47:05
【问题描述】：
在分配给我的使用 Struts2 的项目中，我需要做以下事情，但我是使用 Struts2 的新手。
- 将标题和最常见/重复文本中的文本移动到
.properties文件中。 - 更改图像中的 URL 以使系统参数化，因此它们也应位于同一
.properties文件中。
我已经能够更改一些标题，首先将 Struts2 与我的 .properties 文件链接，然后是 answer。
Content.properties
login.logo=/resources/media/login.png
login.title=Login
现在，我的 JSP 文件仅用作 HTML 文件，它看起来是这样的：
login.jsp
<%@page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@taglib prefix="s" uri="/struts-tags"%>
<%@taglib prefix="sj" uri="/struts-jquery-tags"%>
<%@taglib prefix="sjg" uri="/struts-jquery-grid-tags"%>
<%@taglib prefix="sb" uri="/struts-bootstrap-tags"%>
<%@taglib prefix="decorator" uri="sitemesh-decorator"%>
<%
response.setHeader("Cache-Control", "no-cache"); //HTTP 1.1
response.setHeader("Pragma", "no-cache"); //HTTP 1.0
response.setDateHeader("Expires", -1); //evita o caching no servidor proxy
%>
<!DOCTYPE>
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
<meta charset="UTF-8" />
<title><s:text name="login.title" /></title>
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<link rel="shortcut icon" href='<s:url value="/resources/media/favicon_seg.ico"/>' />
<!-- Le HTML5 shim, for IE6-8 support of HTML elements -->
<!--[if lt IE 9]>
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<sj:head locale="es" jqueryui="true" jquerytheme="ui-lightness" compressed="true" defaultIndicator="ajax_loading" />
<sb:head />
<link rel="stylesheet" href='<s:url value="/resources/css/login.css"/>' />
</head>
<body>
<div class="panel-footer ">
<img height="40" src="<s:url value="/resources/media/login.png"/>" class="pagelogo" alt="Logo" /> My Company
</div>
</body>
</html>
但是，如果我想使用属性文件来更改上面文件中的这一部分，如下所示：
<img height="40" src="<s:url value="${login.logo}"/>" class="pagelogo" alt="Logo" /> My Company
有时我可以正确显示页面，有时不是，但在刷新它 (F5) 后它会再次显示或不显示。当不显示时，我收到以下错误：
SEVERE: Servlet.service() for servlet [jsp] threw exception
org.apache.jasper.JasperException: /WEB-INF/content/login.jsp (line: [87], column: [28]) According to TLD or attribute directive in tag file, attribute [value] does not accept any expressions
at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:42)
at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:291)
at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:114)
at org.apache.jasper.compiler.Validator$ValidateVisitor.checkXmlAttributes(Validator.java:1241)
at org.apache.jasper.compiler.Validator$ValidateVisitor.visit(Validator.java:879)
at org.apache.jasper.compiler.Node$CustomTag.accept(Node.java:1545)
at org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2392)
at org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2444)
at org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2450)
at org.apache.jasper.compiler.Node$Root.accept(Node.java:471)
at org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2392)
at org.apache.jasper.compiler.Validator.validateExDirectives(Validator.java:1853)
at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:221)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:374)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:351)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:335)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:601)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:368)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:59)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:728)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:590)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:524)
at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:895)
at org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:648)
at org.apache.struts2.dispatcher.ServletDispatcherResult.doExecute(ServletDispatcherResult.java:132)
at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:191)
at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:372)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:276)
at org.apache.struts2.interceptor.CookieProviderInterceptor.intercept(CookieProviderInterceptor.java:75)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.CookieInterceptor.intercept(CookieInterceptor.java:258)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.CookieInterceptor.intercept(CookieInterceptor.java:258)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:76)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:253)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
at org.apache.struts2.components.ActionComponent.executeAction(ActionComponent.java:288)
at org.apache.struts2.components.ActionComponent.end(ActionComponent.java:172)
at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
at org.apache.jsp.index_jsp._jspx_meth_s_005faction_005f0(index_jsp.java:168)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:127)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:443)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at com.opensymphony.sitemesh.webapp.SiteMeshFilter.obtainContent(SiteMeshFilter.java:129)
at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:77)
at org.apache.catalina.core.ApplicationFilterC2017-12-11 11:04:52,566 ERROR (org.apache.struts2.components.ActionComponent) - Could not execute action: //login
hain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
获取图像路径并将其显示在 JSP 中而不有时出现上述错误的正确方法是什么？
我发现了一些与此错误相关的问题，但他们使用的是 JSTL，而我没有。
我在写这个问题时发现了另一篇帖子：JSP2 expression in Struts2 form input，他们推荐使用 OGNL，从我读到的表格是：
<s:url ...>
如果我错了，请纠正我，因为这些对我来说是新概念
这是帖子摘录
默认情况下，您不能将 JSP EL 表达式传递给 Struts2 标记。这样做是出于安全目的。如果您愿意，您可以复制 struts-tags.tld 并将所有标签设置为 true。但是，您应该注意允许标签同时接受 JSP EL 和 OGNL 表达式所涉及的安全漏洞。
在调用标签处理程序之前评估 JSP EL，之后评估 OGNL（在标签内）。因此，如果 ${retPage} 评估为 OGNL 表达式，那么标签可能会做一些你没想到的事情。
那么，在这种情况下，是否有任何解决方法可以做我想做的事情（从我的属性文件中获取图像 url 并使用 OGNL 或 EL 显示它？
编辑：
我也试过这个答案的解决方案：https://stackoverflow.com/a/21673153/2180785
这建议将s:url 更改为c:url，在这种情况下它不会产生空白页（正如问题所提到的那样，我在重新加载页面时也会发生这种情况），但这会导致@ 987654336@图片以及一些html如下所示：
如果需要，我可以提供所需的任何额外信息，因为我认为这是需要的信息，但正如我所说，我对这些技术不熟悉，因此不知道是否需要任何其他信息才能完成此问题或清晰到可以回答。
【问题讨论】：