问题描述
我正在使用Struts2,当我访问值堆栈变量时,我不知道是否使用%
或#
或$
.我会尝试所有这些,直到找到正确的.
I'm working with Struts2 and when I'm accessing value stack variables I don't know whether to use %
or #
or $
. I try all of them until I find the correct one.
任何人都可以解释一下两者之间的区别吗?
Can Anybody Explain what is the difference between these?
推荐答案
使用#(井号)
OGNL用于在ActionContext中引用对象,如下所示:
OGNL is used to refer to objects in the ActionContext as follows:
-
objectName
:ValueStack中的对象(OGNL上下文中的默认/根对象),例如Action属性 -
#objectName
:对象位于ActionContext中,但位于ValueStack之外,尤其是...-
#objectName
:使用Struts2数据标签和默认操作范围(例如,<s:set name="foo" value="'Testing'" />
,由<s:property value="#foo" />
引用)创建的ActionContext对象 -
#parameters.objectName
:请求参数 -
#request.objectName
:请求范围的属性 -
#session.objectName
:会话作用域属性 -
#application.objectName
:应用程序范围的属性 -
#attr.objectName
:页面,请求,会话或应用程序范围中的属性(以该顺序搜索)
objectName
: object in the ValueStack (default/root object in the OGNL context), such as an Action property#objectName
: object in the ActionContext but outside of the ValueStack, specifically...#objectName
: ActionContext object that has been created using the Struts2 data tags with the default action scope (e.g.,<s:set name="foo" value="'Testing'" />
, referenced by<s:property value="#foo" />
)#parameters.objectName
: request parameter#request.objectName
: request-scoped attribute#session.objectName
: session-scoped attribute#application.objectName
: application-scoped attribute#attr.objectName
: attribute in page, request, session, or application scope (searched in that order)
可以通过以下两种方式之一使上面的作用域映射引用(参数,请求,会话和应用程序):
The scoped map references above (parameters, request, session, and application) can be made one of two ways:
-
#scopeName.objectName
或 -
#scopeName['objectName']
#scopeName.objectName
or#scopeName['objectName']
%(百分号)的使用
%{ OGNL expression }
用于强制对通常会解释为String文字的属性进行OGNL评估.%{ OGNL expression }
is used to force OGNL evaluation of an attribute that would normally be interpreted as a String literal.示例:
<s:property value="myProperty" default="%{myDynamicDefaultValue}" />
使用@(符号)
@符号用于引用静态属性和方法.请注意,您可能需要在Struts2属性中启用它:
struts.ognl.allowStaticMethodAccess=true
The @ symbol is used to make references to static properties and methods. Note that you may need to enable this in your Struts2 properties:
struts.ognl.allowStaticMethodAccess=true
示例:
@my.package.ClassName@MY_STATIC_PROPERTY @my.package.ClassName@myStaticMethod
使用$(美元符号)
Struts2 OGNL不特别使用美元符号.但是,它可以用于评估正常的JSTL表达式.例如:
Struts2 OGNL does not make special use of the dollar sign. However, it can be used to evaluate normal JSTL expressions. For example:
Struts2:
<h1><s:property value="#pageTitle" /></h1>
(相当于...)
JSTL:<h1>${pageTitle}</h1>
Struts2:
<h1><s:property value="#pageTitle" /></h1>
(is equivalent to...)
JSTL:<h1>${pageTitle}</h1>
这篇关于Struts标记中的#,%和$号有什么区别?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!
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