Spring constructor injection shows null When accessing it on methods

I am developing a small application with Struts2 + Spring + hibernate...Spring beans are injected properly on server start-up .. I have stepped through the setters on start up and they are injecting properly. However, I run the post method and then the post method(execute() in struts2) and the values that were injected ar开发者_如何学运维e null. Why does this happen?

Bean injection is :

<bean id="userAction" class="com.example.user.action.UserAction">
      <constructor-arg  index="0">
            <ref bean="UserServiceTarget"/>
      </constructor-arg>
</bean>

My Struts2 constructor is :

 public UserAction(IUserService userService) 
   {
       this.userService=userService; 

   } 

Struts2 method is :

 public String execute() { 
       this.user=(User)userService.findById(this.id); 
}

But inside execute method userService value is null... When i inject they are injected prperly..

Thank you...

---

I think constructor-args are not the way to ijecting beans to another. I give you an example:

applicationContext.xml:

<bean id="userAction" class="com.example.user.action.UserAction"/>
<bean id="userServiceTarget" class="com.example.user.UserServiceTarget">

UserAction.java:

@Autowired
private UserServiceTarget userService;

You can use other configurations also. For example:

<bean id="userAction" class="com.example.user.action.UserAction">
<property name="userService" ref="UserServiceTarget"/>
</bean>

By this way the Autowired annotation not needed, only a setter.

I don't like xml so much, so the best way is to using Stereotype annotations. You can use @Service annotation on your service class and you can forget to declare the bean in the appcontext, but you should add two lines this way:

<context:annotation-config />

<context:component-scan base-package="com.example"/>

Hope I helped!