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vineri, 24 aprilie 2015

Expose constants and public static methods in EL via OmniFaces

Let's suppose that we have an enum an a helper class, as below:

PlayerEnum

package my.artifacts;

public enum PlayerEnum {
 RAFAEL_NADAL, ROGER_FEDERER, ANDY_MURRAY, NOVAK_DJOKOVIC, MILOS_RAONIC;
   
 public String getFriendlyName(){
  String firstName = name().substring(0, name().indexOf("_"));
  String secondName = name().substring(name().indexOf("_")+1);
  return firstName.charAt(0) + firstName.substring(1).toLowerCase() + " " + secondName.charAt(0) + secondName.substring(1).toLowerCase();
 }
}

PlayerHelper

package my.artifacts;

import java.util.Random;

public final class PlayerHelper {

 public static String addPlayerRank(String name) {
  Random rnd = new Random();
  if (rnd.nextInt(10) < 5) {
      return "Successfully added, " + name + "!";
  }
  return "Ooops! That player " + name + " exist in ATP ranking!";
 }
}

Now, in the JSF page, we want to invoke the PlayerHelper#addPlayerRank() method with the argument, PlayerEnum#ANDY_MURRAY#getFriendlyName() - this could be also a constant of type public static final ... . The problem is that we cannot access constants  or such helper classes via EL. Of course, we can wrap the enum in a bean property and the helper class methods in custom Facelets taglib functions, but it will be much simpler to use OmniFaces <o:inportConstants> and <o:inportFunctions>, which allows us to do this:

<o:importConstants type="my.artifacts.PlayerEnum"/>
<o:importFunctions type="my.artifacts.PlayerHelper"/>

<h5>Insert Andy Murray (PlayerEnum.ANDY_MURRAY) in ATP</h5><br/>       
#{PlayerHelper:addPlayerRank(PlayerEnum.ANDY_MURRAY.getFriendlyName())}

or, using a var attribute:

<o:importConstants type="my.artifacts.PlayerEnum" var="pe"/>
<o:importFunctions type="my.artifacts.PlayerHelper" var="ph"/>
      
<h5>Insert Andy Murray (PlayerEnum.ANDY_MURRAY) in ATP</h5><br/>       
#{ph:addPlayerRank(pe.ANDY_MURRAY.getFriendlyName())}

Complete source code in GitHub.
More examples in OmniFaces Showcase.

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