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Struts Bean Tags |
This tag library contains tags useful in accessing beans and their
properties, as well as defining new beans (based on these accesses)
that are accessible to the remainder of the page via scripting variables
and page scope attributes. Convenient mechanisms to create new beans
based on the value of request cookies, headers, and parameters are also
provided.
Many of the tags in this tag library will throw a
JspException at runtime when they are utilized incorrectly
(such as when you specify an invalid combination of tag attributes). JSP
allows you to declare an "error page" in the <%@ page %>
directive. If you wish to process the actual exception that caused the
problem, it is passed to the error page as a request attribute under key
org.apache.struts.action.EXCEPTION .
If you are viewing this page from within the Struts Documentation
Application (or online at
http://jakarta.apache.org/struts), you can learn more about using
these tags in the
Bean Tags Developer's Guide.
| Tag Name | Description |
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include |
Load the response from a dynamic application request and make it available
as a bean.
| message |
Render an internationalized message string to the response.
| page |
Expose a specified item from the page context as a bean.
| resource |
Load a web application resource and make it available as a bean.
| size |
Define a bean containing the number of elements in a Collection or Map.
| struts |
Expose a named Struts internal configuration object as a bean.
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include -
Load the response from a dynamic application request and make it available
as a bean.
|
Perform an internal dispatch to the specified application component
(or external URL)
and make the response data from that request available as a scoped variable of
type String . This tag has a function similar to that of
the standard <jsp:include> tag, except that the
response data is stored in a page scope attribute instead of being
written to the output stream. If the current request is part of a
session, the generated request for the include will also include the
session identifier (and thus be part of the same session).
The URL used to access the specified application component is
calculated based on which of the following attributes you specify
(you must specify exactly one of them):
- forward - Use the value of this attribute as the name
of a global
ActionForward to be looked up, and
use the module-relative or context-relative URI found there.
- href - Use the value of this attribute unchanged (since
this might link to a resource external to the application, the
session identifier is not included.
- page - Use the value of this attribute as an
module-relative URI to the desired resource.
| Attribute Name | Description |
---|
anchor |
Optional anchor tag ("#xxx") to be added to the generated
hyperlink. Specify this value without any
"#" character.
[RT Expr]
| forward |
Logical name of a global ActionForward that contains
the actual content-relative URI of the resource to be included.
[RT Expr]
| href |
Absolute URL (including the appropriate protocol prefix such as
"http:") of the resource to be included. Because this URL could be
external to the current web application, the session identifier will
not be included in the request.
[RT Expr]
| id |
Specifies the name of the scripting variable (and associated page
scope attribute) that will be made available with the value of the
specified web application resource.
[Required]
| name |
Module-relative name (starting with a '/') of the web application
resource to be dispatched, and whose response data is to be made
available as a bean.
[RT Expr]
| page |
Module-relative URI (starting with a '/') of the web application
resource to be included.
[RT Expr]
| transaction |
Set to true if you want the current
transaction control token included in the generated
URL for this include.
[RT Expr]
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message -
Render an internationalized message string to the response.
|
Retrieves an internationalized message for the specified locale,
using the specified message key, and write it to the output stream.
Up to five parametric replacements (such as "{0}") may be specified.
The message key may be specified directly, using the key
attribute, or indirectly, using the name and
property attributes to obtain it from a bean.
JSTL: The equivalent JSTL tag is <fmt:message>. For example,
<fmt:message key="my.msg.key">
<fmt:param value="replacement text"/>
</fmt:message>
| Attribute Name | Description |
---|
arg0 |
First parametric replacement value, if any.
[RT Expr]
| arg1 |
Second parametric replacement value, if any.
[RT Expr]
| arg2 |
Third parametric replacement value, if any.
[RT Expr]
| arg3 |
Fourth parametric replacement value, if any.
[RT Expr]
| arg4 |
Fifth parametric replacement value, if any.
[RT Expr]
| bundle |
The name of the application scope bean under which the
MessageResources object containing our messages
is stored.
[RT Expr]
| key |
The message key of the requested message, which must have
a corresponding value in the message resources. If not specified,
the key is obtained from the name and
property attributes.
[RT Expr]
| locale |
The name of the session scope bean under which our currently
selected Locale object is stored.
[RT Expr]
| name |
Specifies the attribute name of the bean whose property is accessed
to retrieve the value specified by property (if
specified). If property is not specified, the value of
this bean itself will be used as the message resource key.
[RT Expr]
| property |
Specifies the name of the property to be accessed on the bean
specified by name . This value may be a simple, indexed,
or nested property reference expression. If not specified, the value
of the bean identified by name will itself be used as the
message resource key.
[RT Expr]
| scope |
Specifies the variable scope searched to retrieve the bean specified
by name . If not specified, the default rules applied by
PageContext.findAttribute() are applied.
[RT Expr]
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page -
Expose a specified item from the page context as a bean.
|
Retrieve the value of the specified item from the page context
for this page, and define it as a scripting variable, and a page scope
attribute accessible to the remainder of the current page.
If a problem occurs while retrieving the specified configuration
object, a request time exception will be thrown.
| Attribute Name | Description |
---|
id |
Specifies the name of the scripting variable (and associated
page scope attribute) that will be made available with the value of
the specified page context property.
[Required]
| property |
Name of the property from our page context to be retrieved and
exposed. Must be one of application , config ,
request , response , or session .
[Required]
[RT Expr]
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resource -
Load a web application resource and make it available as a bean.
|
Retrieve the value of the specified web application resource, and make
it available as either a InputStream or a String ,
depending on the value of the input attribute.
If a problem occurs while retrieving the specified resource, a
request time exception will be thrown.
| Attribute Name | Description |
---|
id |
Specifies the name of the scripting variable (and associated page
scope attribute) that will be made available with the value of the
specified web application resource.
[Required]
| input |
If any arbitrary value for this attribute is specified, the resource
will be made available as an InputStream . If this
attribute is not specified, the resource will be made available
as a String .
[RT Expr]
| name |
Module-relative name (starting with a '/') of the web application
resource to be loaded and made available.
[Required]
[RT Expr]
|
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size -
Define a bean containing the number of elements in a Collection or Map.
|
Given a reference to an array, Collection or Map, creates a new bean, of
type java.lang.Integer , whose value is the number of elements
in that collection. You can specify the collection to be counted in any
one of the following ways:
- As a runtime expression specified as the value of the
collection attribute.
- As a JSP bean specified by the
name attribute.
- As the property, specified by the
property attribute,
of the JSP bean specified by the name attribute.
| Attribute Name | Description |
---|
collection |
A runtime expression that evaluates to an array, a Collection, or
a Map.
[RT Expr]
| id |
The name of a page scope JSP bean, of type
java.lang.Integer , that will be created to contain the
size of the underlying collection being counted.
[Required]
| name |
The name of the JSP bean (optionally constrained to the scope
specified by the scope attribute) that contains the
collection to be counted (if property is not specified),
or whose property getter is called to return the collection to be
counted (if property is specified.
[RT Expr]
| property |
The name of the property, of the bean specified by the
name attribute, whose getter method will return the
collection to be counted.
[RT Expr]
| scope |
The bean scope within which to search for the JSP bean specified
by the name attribute. If not specified, the available
scopes are searched in ascending sequence.
[RT Expr]
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struts -
Expose a named Struts internal configuration object as a bean.
|
Retrieve the value of the specified Struts internal configuration
object, and define it as a scripting variable and as a page scope
attribute accessible to the remainder of the current page. You must
specify exactly one of the formBean , forward ,
and mapping attributes to select the configuration object
to be exposed.
If a problem occurs while retrieving the specified configuration
object, a request time exception will be thrown.
| Attribute Name | Description |
---|
id |
Specifies the name of the scripting variable (and associated
page scope attribute) that will be made available with the value of
the specified Struts internal configuration object.
[Required]
| formBean |
Specifies the name of the Struts ActionFormBean
definition object to be exposed.
[RT Expr]
| forward |
Specifies the name of the global Struts ActionForward
definition object to be exposed.
[RT Expr]
| mapping |
Specifies the matching path of the Struts ActionMapping
definition object to be exposed.
[RT Expr]
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