我可以从会话属性获取属性，但不能从会话映射中获取属性 [英] I can get property from a session attribute, but not from a session map

问题描述

我正在使用SSH2。当我尝试使用<％= session.getAttribute（username）％> 获取属性时，它恰到好处。但是当我尝试使用< s：property value =＃session.username/> 获得相同的属性时，我什么也没得到。

I am using SSH2. When I try to got an attribute with <%=session.getAttribute("username") %>, it was just right. But when I tried to get the same attribute with <s:property value="#session.username" />, I got nothing.

为什么？它们不一样吗？

Why? Aren't they the same?

当我使用< s：debug> 时，我得到了这些：

And when I used the <s:debug>, I got these:

Servlet.service() for servlet jsp threw exception
org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:167)
    at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:215)
    at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:190)
    at com.bizplus.server.po.Power_$$_javassist_0.toString(Power_$$_javassist_0.java)
    at java.lang.String.valueOf(String.java:2827)
    at java.lang.StringBuilder.append(StringBuilder.java:115)
    at java.util.AbstractCollection.toString(AbstractCollection.java:422)
    at java.lang.String.valueOf(String.java:2827)
    at java.lang.StringBuilder.append(StringBuilder.java:115)
    at java.util.AbstractMap.toString(AbstractMap.java:490)
    at java.lang.String.valueOf(String.java:2827)
    at java.lang.StringBuffer.append(StringBuffer.java:219)
    at freemarker.ext.beans.SimpleMethodModel.exec(SimpleMethodModel.java:130)
    at freemarker.core.MethodCall._getAsTemplateModel(MethodCall.java:93)
    at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
    at freemarker.core.Expression.getStringValue(Expression.java:93)
    at freemarker.core.StringBuiltins$StringBuiltIn._getAsTemplateModel(StringBuiltins.java:71)
    at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
    at freemarker.core.Expression.getStringValue(Expression.java:93)
    at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.IfBlock.accept(IfBlock.java:82)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.MixedContent.accept(MixedContent.java:92)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
    at freemarker.core.Environment.visit(Environment.java:417)
    at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.MixedContent.accept(MixedContent.java:92)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.Environment.include(Environment.java:1483)
    at freemarker.core.Include.accept(Include.java:169)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.MixedContent.accept(MixedContent.java:92)
    at freemarker.core.Environment.visit(Environment.java:210)
    at freemarker.core.Environment.process(Environment.java:190)
    at freemarker.template.Template.process(Template.java:237)
    at org.apache.struts2.components.template.FreemarkerTemplateEngine.renderTemplate(FreemarkerTemplateEngine.java:157)
    at org.apache.struts2.components.UIBean.mergeTemplate(UIBean.java:559)
    at org.apache.struts2.components.UIBean.end(UIBean.java:513)
    at org.apache.struts2.views.jsp.ComponentTagSupport.doEndTag(ComponentTagSupport.java:42)
    at org.apache.jsp.test_jsp._jspx_meth_s_005fdebug_005f0(test_jsp.java:133)
    at org.apache.jsp.test_jsp._jspService(test_jsp.java:88)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
    at org.apache.jasper.servlet.JspServlet._serviceJspFile(JspServlet.java:320)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:428)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
    at java.lang.Thread.run(Thread.java:619)

看来Hibernate中的会话。为什么？

It seems the session in Hibernate. Why?

推荐答案

是的，它们不同，在你使用http会话隐式对象的scriptlet中，在struts标签中属性引用通过OGNL检索的struts会话映射对象。你没有什么因为他们是不同的。要使用struts会话映射，您应该在操作中实现 SessionAware 。因此，servlet配置拦截器会向其注入会话，然后您可以使用会话映射来放置值，这些值可以通过OGNL访问。

Yes, they are not the same, in the scriptlet you use the http session implicit object, in the struts tag attribute you reference the struts session map object, retrieved via OGNL. You got nothing just because they are different. To use the struts session map you should implement SessionAware in the action. So, the servlet config interceptor will inject the session to it, then you could use the session map to put there values, that will be accessible via OGNL.

示例 SessionAware 实施：

private Map<String, Object> session;

@Override
public void setSession(Map<String, Object> session) {
 this.session = session;
} 

因为你没有实现而发生延迟初始化异常模型实体中的toString 。

参见访问应用程序，会话，请求对象

这篇关于我可以从会话属性获取属性，但不能从会话映射中获取属性的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！