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.
Retrieve the value of the specified request cookie (as a single
value or multiple values, depending on the multiple attribute),
and define the result as a page scope attribute of type Cookie
(if multiple is not specified) or Cookie[]
(if multiple is specified).
If no cookie with the specified name can be located, and no default value is specified, a request time exception will be thrown.
]]>Cookie[]. If not specified, the first value for the
specified cookie will be retrieved as a value of type
Cookie.
]]>
Create a new attribute (in the scope specified by the
toScope property, if any), and a corresponding scripting
variable, both of which are named by the value of the id
attribute. The corresponding value to which this new attribute (and
scripting variable) is set are specified via use of exactly one of the
following approaches (trying to use more than one will result in a
JspException being thrown):
name attribute (plus optional
property and scope attributes) -
The created attribute and scripting variable will be of the type of the
retrieved JavaBean property, unless it is a Java primitive type,
in which case it will be wrapped in the appropriate wrapper class
(i.e. int is wrapped by java.lang.Integer).value attribute - The created attribute and
scripting variable will be of type java.lang.String,
set to the value of this attribute.java.lang.String, set to
the value of the nested body content.If a problem occurs while retrieving the specified bean property, a request time exception will be thrown.
The <bean:define> tag differs from
<jsp:useBean> in several ways, including:
value
attribute.<jsp:setProperty> tags) that are only executed
if a bean was actually created.USAGE NOTE - There is a restriction in the JSP 1.1
Specification that disallows using the same value for an id
attribute more than once in a single JSP page. Therefore, you will not
be able to use <bean:define> for the same bean
name more than once in a single page.
USAGE NOTE - If you use another tag to create the body content (e.g. bean:write), that tag must return a non-empty String. An empty String equates to an empty body or a null String, and a new scripting variable cannot be defined as null. Your bean must return a non-empty String, or the define tag must be wrapped within a logic tag to test for an empty or null value.
USAGE NOTE - You cannot use bean:define to instantiate a DynaActionForm (type="org.apache.struts.action.DynaActionForm") with the properties specified in the struts-config. The mechanics of creating the dyna-properties is complex and cannot be handled by a no-argument constructor. If you need to create an ActionForm this way, you must use a conventional ActionForm.
See the Bean Developer's Guide section on bean creation for more information about these differences, as well as alternative approaches to introducing beans into a JSP page.
]]>property is also
specified) or the attribute name of the bean that is duplicated with
the new reference created by this tag (if property is not
also specified). This attribute is required unless you specify
a value attribute or nested body content.
]]>
name. This value may be a simple, indexed,
or nested property reference expression. If not specified, the bean
identified by name is given a new reference identified by
id.
]]>
name. If not specified, the default rules applied by
PageContext.findAttribute() are applied.
]]>
page scope.
]]>
id attribute.
]]>
java.lang.String value to which the exposed bean
should be set. This attribute is required unless you specify the
name attribute or nested body content.
]]>
Retrieve the value of the specified request header (as a single
value or multiple values, depending on the multiple attribute),
and define the result as a page scope attribute of type String
(if multiple is not specified) or String[]
(if multiple is specified).
If no header with the specified name can be located, and no default value is specified, a request time exception will be thrown.
]]>HttpServletRequest.getHeaders() and a definition of the
result as a bean of type String[]. Otherwise,
HttpServletRequest.getHeader() will be called, and a
definition of the result as a bean of type String
will be performed.
]]>
Perform an internal dispatch to the specified application component
(or external URL)
and make the response data from that request available as a bean 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):
ActionForward to be looked up, and
use the module-relative or context-relative URI found there.ActionForward that contains
the actual content-relative URI of the resource to be included.
]]>
true if you want the current
transaction control token included in the generated
URL for this include.
]]>
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>
MessageResources object containing our messages
is stored.
]]>
name and
property attributes.
]]>
Locale object is stored.
]]>
property (if
specified). If property is not specified, the value of
this bean itself will be used as the message resource key.
]]>
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.
]]>
name. If not specified, the default rules applied by
PageContext.findAttribute() are applied.
]]>
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.
]]>application, config,
request, response, or session.
]]>
Retrieve the value of the specified request parameter (as a single
value or multiple values, depending on the multiple attribute),
and define the result as a page scope attribute of type String
(if multiple is not specified) or String[]
(if multiple is specified).
If no request parameter with the specified name can be located, and no default value is specified, a request time exception will be thrown.
]]>ServletRequest.getParameterValues() and a definition of
the result as a bean of type String[]. Otherwise,
ServletRequest.getParameter() will be called, and a
definition of the result as a bean of type String
will be performed.
]]>
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.
]]>InputStream. If this
attribute is not specified, the resource will be made available
as a String.
]]>
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:
collection attribute.name attribute.property attribute,
of the JSP bean specified by the name attribute.java.lang.Integer, that will be created to contain the
size of the underlying collection being counted.
]]>
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.
]]>
name attribute, whose getter method will return the
collection to be counted.
]]>
name attribute. If not specified, the available
scopes are searched in ascending sequence.
]]>
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.
]]>ActionFormBean
definition object to be exposed.
]]>
ActionForward
definition object to be exposed.
]]>
ActionMapping
definition object to be exposed.
]]>
Retrieve the value of the specified bean property, and render it to the current JspWriter as a String by the ways:
format attribute exists then value will be formatted on base of format
string from format attribute and default system locale.format
attribute description) then value will be formatted on base of format string
from resources. Resources bundle and target locale can be specified with
bundle and locale attributes. If nothing specified then
default resource bundle and current user locale will be used.getAsText() method will be called.toString() conversions will be applied.When a format string is provided, numeric values are formatted using the
java.text.DecimalFormat class; if the format string came from
a resource, the applyLocalisedPattern() method is used, and
applyPattern() is used otherwise. Dates are formatted using
the SimpleDateFormat class. For details of the specific format
patterns, please see the Javadocs for those classes.
If a problem occurs while retrieving the specified bean property, a request time exception will be thrown.
]]>MessageResources object containing our messages
is stored.
]]>
true, the rendered property
value will be filtered for characters that are sensitive in HTML, and any
such characters will be replaced by their entity equivalents.
]]>
String. If nothing specified, then default format
string for value data type will be searched in message resources by
according key.
]]>
true, and the bean specified
by the name and scope attributes does not
exist, simply return without writing anything. If this attribute is
set to false, a runtime exception to be thrown,
consistent with the other tags in this tag library.
]]>
Locale object is stored.
]]>
property (if
specified). If property is not specified, the value of
this bean itself will be rendered.
]]>
name. This value may be a simple, indexed,
or nested property reference expression. If not specified, the bean
identified by name will itself be rendered. If the
specified property returns null, no output will be rendered.
]]>
name. If not specified, the default rules applied by
PageContext.findAttribute() are applied.
]]>