T5 How to difine dynamic path for image

[Doublel]

 Hi:
   I have a problem  I get a value from DB  into private String
weatherPath="";
  then  the code is :

  public void  onActivate(String id){
    if (lw.hnSunny.equals(bc.getLogWeather())){
             this.weatherPath="logweath.gif";

         }
}

    @Inject
    @Path("context:/images/"+ weatherPath )
    private Asset trackback;

  I want to implement   image can dynamic by var  weatherPath

  can give some advice ??
 thanks
-- 
得与失都是生活