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

问题描述

我使用的是 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"/> 获取相同的属性时，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?他们不一样吗?

Why? Aren't they the same?

当我使用 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)

似乎是 Hibernate 中的会话.为什么?

It seems the session in Hibernate. Why?

推荐答案

是的，它们不一样，在scriptlet中你使用了http会话隐式对象，在struts标签属性中你引用了struts会话映射对象，检索通过OGNL.你一无所获，只是因为它们不同.要使用 struts 会话映射，您应该在操作中实现 SessionAware.因此，servlet 配置拦截器会将会话注入其中，然后您可以使用会话映射将值放在那里，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.

SessionAware 实现示例:

private Map<String, Object> session;

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

延迟初始化异常发生是因为您没有在模型实体中实现 toString.

lazy initialization exception happens because you didn't implement toString in the model entities.

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中获取属性，但不能从会话映射中获取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！