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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.

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The example application that supports this tutorial (Wildcard_Method_Struts2 available at http://code.google.com/p/struts2-examples/downloads/list^{Image Removed}.) 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.

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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:

<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>

So even for this simple application, I'd have to write four separate action mapping nodes (create, edit, delete, saveOrUpdate) in the configuration file. So you can easily see that a more complex application can have dozens of action mapping nodes.

To implement the wildcard method selection technique to enable the Struts 2 framework to dynamically select the correct method to call at runtime you just need to use the wildcard character, *, in your name value and an attribute value place holder ( {1} ) for the method value. For example:

<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>

The * is the wildcard character. Any action name values that end in "Person" will be handled by this action mapping. Whatever value is before "Person" will be the value used for the method attribute (the {1} place holder will be replaced with that value). For example this URL:

http://localhost:8080/Wildcard_Method_Struts_2_Mvnwildcard-method-selection/createPerson.action^{Image Removed}

will be be processed by the the above action mapping and method create of class PersonAction will be called. While this URL

http://localhost:8080/Wildcard_Method_Struts_2_Mvnwildcard-method-selection/deletePerson.action^{Image Removed}

will cause the delete method of class PersonAction to be called.

What happens if we have a URL with nothing in front of Person? For example:

http://localhost:8080/Wildcard_Method_Struts_2_Mvnwildcard-method-selection/Person.action^{Image Removed}

If there is no value in front of Person, then the Struts 2 framework will call the execute method of the class PersonAction.

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