#{resource} EL 在哪里指定？
Where is #{resource} EL specified?
在 JSF 页面中，我使用 EL 来定位放置在 /resource/images/ 文件夹中的图像。
<h:graphicImage value="#{resource['images:logo.gif']}"
EL如何定位图片？
也许一个规范定义了规则，但我不知道是哪个规范。
我试图在 JSR-000344 JavaServer Faces 2.2 ，the JSR-000342 Java Platform, Enterprise Edition 7, the JSR-000341 Expression Language 3.0 中找到它，但没有找到。
在JSF 2.0 specification中，2.6.2章节首次提到：
2.6.2 Rendering Resources
Resources such as images, stylesheets and scripts use the resource handling mechanism as outlined in Section 2.6.1
“Packaging Resources”. So, for example:
<h:graphicImage name=”Planets.gif” library=”images”/>
<h:graphicImage value=”#{resource[‘images:Planets.gif’]}”/>
These entries render exactly the same markup. In addition to using the name and library attributes, stylesheet and
script resources can be “relocated” to other parts of the view. For example, we could specify that a script resource be
rendered within an HTML “head”, “body” or “form” element in the page.
然后在第 5.6.2.5 章中：
5.6.2.5 Resource ELResolver
This resolver is a means by which Resource instances are encoded into a faces request such that a subsequent faces
resource request from the browser can be satisfied using the ResourceHandler as described in Section 2.6 “Resource
Handling”.
ELResolver method implementation requirements
If base and property are not null, and base is an
instance of ResourceHandler (as will be the case
with an expression such as #{resource[‘ajax.js’]},
perform the following. (Note: This is possible due
to the ImplicitObjectELResolver returning the
ResourceHandler, see Section 5.6.2.1 “Implicit
Object ELResolver for Facelets and Programmatic
Access”)
- If property does not contain a colon
character ‘:’, treat property as the
resourceName and pass property to
ResourceHandler.createResource(resourceName).
- If property contains a single colon
character ‘:’, treat the content before the ‘:’ as
the
libraryName and the content after the ‘:’
as the resourceName and pass both to
ResourceHandler.createResource(resourceName, libraryName)
- If property contains more than one colon
character ‘:’, throw a localized
ELException, including property.
If one of the above steps results in the creation
of a non-null Resource instance, call
ELContext.setPropertyResolved(true) and return the
result of calling the getRequestPath() method on
the Resource instance.
它也在 JSF 2.1 和 2.2 规范的相同章节中提到。
与具体问题无关，images是资源库名称的一个非常糟糕的例子。不要从规范示例中接管它。
另请参阅：
- How to reference CSS / JS / image resource in Facelets template?
- What is the JSF resource library for and how should it be used?
在 JSF 页面中，我使用 EL 来定位放置在 /resource/images/ 文件夹中的图像。
<h:graphicImage value="#{resource['images:logo.gif']}"
EL如何定位图片？ 也许一个规范定义了规则，但我不知道是哪个规范。 我试图在 JSR-000344 JavaServer Faces 2.2 ，the JSR-000342 Java Platform, Enterprise Edition 7, the JSR-000341 Expression Language 3.0 中找到它，但没有找到。
在JSF 2.0 specification中，2.6.2章节首次提到：
2.6.2 Rendering Resources
Resources such as images, stylesheets and scripts use the resource handling mechanism as outlined in Section 2.6.1 “Packaging Resources”. So, for example:
<h:graphicImage name=”Planets.gif” library=”images”/> <h:graphicImage value=”#{resource[‘images:Planets.gif’]}”/>These entries render exactly the same markup. In addition to using the
nameandlibraryattributes, stylesheet and script resources can be “relocated” to other parts of the view. For example, we could specify that a script resource be rendered within an HTML “head”, “body” or “form” element in the page.
然后在第 5.6.2.5 章中：
5.6.2.5 Resource ELResolver
This resolver is a means by which
Resourceinstances are encoded into a faces request such that a subsequent faces resource request from the browser can be satisfied using the ResourceHandler as described in Section 2.6 “Resource Handling”.ELResolver method implementation requirements
If base and property are not null, and base is an instance of
ResourceHandler(as will be the case with an expression such as#{resource[‘ajax.js’]}, perform the following. (Note: This is possible due to theImplicitObjectELResolverreturning theResourceHandler, see Section 5.6.2.1 “Implicit Object ELResolver for Facelets and Programmatic Access”)
- If property does not contain a colon character ‘:’, treat property as the
resourceNameand pass property toResourceHandler.createResource(resourceName).- If property contains a single colon character ‘:’, treat the content before the ‘:’ as the
libraryNameand the content after the ‘:’ as theresourceNameand pass both toResourceHandler.createResource(resourceName, libraryName)- If property contains more than one colon character ‘:’, throw a localized
ELException, including property.If one of the above steps results in the creation of a non-null
Resourceinstance, callELContext.setPropertyResolved(true)and return the result of calling thegetRequestPath()method on theResourceinstance.
它也在 JSF 2.1 和 2.2 规范的相同章节中提到。
与具体问题无关，images是资源库名称的一个非常糟糕的例子。不要从规范示例中接管它。
另请参阅：
- How to reference CSS / JS / image resource in Facelets template?
- What is the JSF resource library for and how should it be used?