Better URLs with Struts2

I’m going to show you how to use the NamedVariablePatternMatcher to build better URLs with Struts2.

Before: http://www.example.com/profiles?username=steven
After: http://www.example.com/profiles/steven

For this example, we’ll map an action that displays a user’s profile page.

The Action

public class ViewProfileAction {
  private String username;

  public String execute() {
    // look up the appropriate user by username and
    // expose the user to the JSP with a getUser() method.
  }

  @RequestParameter
  public void setUsername(String username) {
    this.username = username;
  }
}

The Standard Mapping

<action name="profiles" class="com.example.actions.ViewProfileAction">
  <result name="input">/WEB-INF/jsp/profile.jsp</result>
</action>

The Improved Mapping

First, we need to set a few constants in our struts.xml file to enable named variable pattern matching.

<constant name="struts.mapper.alwaysSelectFullNamespace" value="false"/>
<constant name="struts.enable.SlashesInActionNames" value="true"/>
<constant name="struts.patternMatcher" value="namedVariable"/>

Next, we’ll revise the action mapping as follows.

<action name="profiles/{username}" class="com.example.actions.ViewProfileAction">
  <result name="input">/WEB-INF/jsp/profile.jsp</result>
</action>

For the URL profiles/steven, Struts2 will invoke our ViewProfileAction and pass the value steven to the setUsername method of the action.

Happy action mapping!

Important Note

Only one PatternMatcher implementation can be used at a time. The two implementations included with Struts2 are mutually exclusive. You cannot use wildcards and named variable patterns in the same application (if that were required, you’d need to create a custom PatternMatcher implementation).