THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
| Info |
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The example code for this tutorial, wildcard_method_selection, is available for checkout at https://github.com/apache/struts-examples |
Introduction
In this tutorial we'll cover how to configure an action node in the struts.xml configuration file so that one action node can be used to relate several different Action URLs to specific methods of the Action class. This will reduce the number of action nodes we must write in the struts.xml configuration file.
| Tip |
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The Struts 2 user mailing list is an excellent place to get help. If you are having a problem getting the tutorial example applications to work search the Struts 2 mailing list. If you don't find an answer to your problem, post a question on the mailing list. |
Example Application
The example application that supports this tutorial shows how to use Struts 2's wildcard method selection methodology. The example application is just a simple one that lists some people and lets you edit them, delete them, and add a new person to the list. Everything that the application needs to do with a Person (the model class) is controlled by the Struts 2 ActionSupport class PersonAction. The PersonAction class has several different methods (e.g. create, edit, delete) that are called depending on what the user wants to do.
Wildcard Method Selection
Without using the wildcard method selection technique, I'd have to write an action mapping node in the Struts 2 configuration file for each separate action I'd want to call. For example:
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{info}The example code for this tutorial, Wildcard_Method_Struts2_Ant or Wildcard_Method_Struts2_Mvn, is available on Google Code - http://code.google.com/p/struts2-examples/downloads/list. After downloading and unzipping the file, you'll have a folder named Wildcard_Method_Struts2_Ant (or Wildcard_Method_Struts2_Mvn). In that folder will be a README.txt file with instructions on now to build and run the example application.{info} h3. Introduction In this tutorial we'll cover how to configure an action node in the struts.xml configuration file so that one action node can be used to relate several different Action URLs to specific methods of the Action class. This will reduce the number of action nodes we must write in the struts.xml configuration file. {tip}The [Struts 2 user mailing list|http://struts.apache.org/mail.html] is an excellent place to get help. If you are having a problem getting the tutorial example applications to work search the Struts 2 mailing list. If you don't find an answer to your problem, post a question on the mailing list.{tip} h3. Example Application The example application that supports this tutorial (Wildcard_Method_Struts2 available at http://code.google.com/p/struts2-examples/downloads/list.) shows how to use Struts 2's wildcard method selection methodology. The example application is just a simple one that lists some people and lets you edit them, delete them, and add a new person to the list. Everything that the application needs to do with a Person (the model class) is controlled by the Struts 2 ActionSupport class PersonAction. The PersonAction class has several different methods (e.g. create, edit, delete) that are called depending on what the user want's to do. h3. Wildcard Method Selection Without using the wildcard method selection technique, I'd have to write an action mapping node in the Struts 2 configuration file for each separate action I'd want to call. For example: {code:XML:title=Struts.xml Action Configuration} <action name="createPerson" class="org.apache.struts.tutorials.wildcardmethod.action.PersonAction" method="create"> <result name="input">input.jsp</result> <result name="success">view.jsp</result> </action> <action name="editPerson" class="org.apache.struts.tutorials.wildcardmethod.action.PersonAction" method="edit"> <result name="input">input.jsp</result> <result name="success">view.jsp</result> </action> {code} So even for this simple application, |
So even for this simple application, I'd
...
have
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to
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write
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four
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separate
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action
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mapping
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nodes
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(create,
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edit,
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delete,
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saveOrUpdate)
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in
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the
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configuration
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file.
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So
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you
...
can
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easily
...
see
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that
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a
...
more
...
complex
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application
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can
...
have
...
dozens
...
of
...
action
...
mapping
...
nodes.
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To
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implement
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the
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wildcard
...
method
...
selection
...
technique
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to
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enable
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the
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Struts
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2
...
framework
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to
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dynamically
...
select
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the
...
correct
...
method
...
to
...
call
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at
...
runtime
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you
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just
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need
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to
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use
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the
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wildcard
...
character,
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*,
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in
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your
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name
...
value
...
and
...
an
...
attribute
...
value
...
place
...
holder
...
(
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{1}
...
)
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for
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the
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method
...
value.
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For
...
example:
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} <action name="*Person" class="org.apache.struts.tutorials.wildcardmethod.action.PersonAction" method="{1}"> <result name="success">view.jsp</result> <result name="input">input.jsp</result> </action> {code} |
The
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*
...
is
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the
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wildcard
...
character.
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Any
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action
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name
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values
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that
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end
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in
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"Person"
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will
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be
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handled
...
by
...
this
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action
...
mapping.
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Whatever
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value
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is
...
before
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"Person"
...
will
...
be
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the
...
value
...
used
...
for
...
the
...
method
...
attribute
...
(the
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{1}
...
place
...
holder
...
will
...
be
...
replaced
...
with
...
that
...
value).
...
For
...
example
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this
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URL:
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...
wildcard-method-selection/createPerson.action
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will
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be
...
be
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processed
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by
...
the
...
the
...
above
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action
...
mapping
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and
...
method
...
create
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of
...
class
...
PersonAction
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will
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be
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called.
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While
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this
...
URL
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wildcard-method-selection/deletePerson.action
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will
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cause
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the
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delete
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method
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of
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class
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PersonAction
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to
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be
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called.
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What
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happens
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if
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we
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have
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a
...
URL
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with
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nothing
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in
...
front
...
of
...
Person?
...
For
...
example:
...
...
wildcard-method-selection/Person.action
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If
...
there
...
is
...
no
...
value
...
in
...
front
...
of
...
Person,
...
then
...
the
...
Struts
...
2
...
framework
...
will
...
call
...
the
...
execute
...
method
...
of
...
the
...
class
...
PersonAction.
...
Dynamic
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Method
...
Invocation
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The
...
wildcard
...
method
...
selection
...
technique
...
explained
...
above
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should
...
not
...
be
...
confused
...
with
...
the
...
"Dynamic
...
Method
...
Invocation"
...
technique.
...
The
...
Struts
...
2
...
documentation
...
explains
...
this
...
technique
...
(which
...
uses
...
the
...
bang,
...
!,
...
operator
...
in
...
the
...
action
...
name)
...
and
...
recommends
...
against
...
using
...
the
...
"Dynamic
...
Method
...
Invocation"
...
technique
...
due
...
to
...
security
...
and
...
other
...
reasons
...
related
...
to
...
how
...
this
...
technique
...
is
...
implemented
...
internally.
...
The
...
Struts
...
2
...
documentation
...
also
...
recommends
...
turning
...
off
...
the
...
option
...
to
...
use
...
the
...
dynamic
...
method
...
invocation
...
by
...
setting
...
struts.enable.DynamicMethodInvocation
...
to
...
FALSE
...
in
...
the
...
Struts
...
configuration.
...
Summary
By using the wildcard method selection technique explained above, you can significantly reduce the number of action mapping nodes you need to write and manage in the Struts 2 XML configuration file.
Up Next
In our next tutorial we'll cover how control the appearance of the Struts 2 tags when they are rendered in the browser.
Next | Onward to Struts 2 Themes |
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