public final ApplicationContext getApplicationContext() throws IllegalStateException 
{
		if (this.applicationContext == null && isContextRequired()) {
			throw new IllegalStateException(
					"ApplicationObjectSupport instance [" + this + "] does not run in an ApplicationContext");
		}
		return this.applicationContext;
}

Return the ApplicationContext that this object is associated with.

 protected final MessageSourceAccessor getMessageSourceAccessor() throws IllegalStateException 
{
		if (this.messageSourceAccessor == null && isContextRequired()) {
			throw new IllegalStateException(
					"ApplicationObjectSupport instance [" + this + "] does not run in an ApplicationContext");
		}
		return this.messageSourceAccessor;
}

Return a MessageSourceAccessor for the application context used by this object, for easy message access.

 protected  void initApplicationContext() throws BeansException 
{

}

Subclasses can override this for custom initialization behavior.

The default implementation is empty. Called by #initApplicationContext(org.springframework.context.ApplicationContext) .

 protected  void initApplicationContext(ApplicationContext context) throws BeansException 
{
		initApplicationContext();
}

Subclasses can override this for custom initialization behavior. Gets called by setApplicationContext after setting the context instance.

Note: Does not get called on reinitialization of the context but rather just on first initialization of this object's context reference.

The default implementation calls the overloaded #initApplicationContext() method without ApplicationContext reference.

 protected boolean isContextRequired() 
{
		return false;
}

Determine whether this application object needs to run in an ApplicationContext.

Default is "false". Can be overridden to enforce running in a context (i.e. to throw IllegalStateException on accessors if outside a context).

 protected Class requiredContextClass() 
{
		return ApplicationContext.class;
}

Determine the context class that any context passed to setApplicationContext must be an instance of. Can be overridden in subclasses.

 public final  void setApplicationContext(ApplicationContext context) throws BeansException 
{
	       
		if (context == null && !isContextRequired()) {
			// Reset internal context state.
			this.applicationContext = null;
			this.messageSourceAccessor = null;
		}
		else if (this.applicationContext == null) {
			// Initialize with passed-in context.
			if (!requiredContextClass().isInstance(context)) {
				throw new ApplicationContextException(
						"Invalid application context: needs to be of type [" + requiredContextClass().getName() + "]");
			}
			this.applicationContext = context;
			this.messageSourceAccessor = new MessageSourceAccessor(context);
			initApplicationContext(context);
		}
		else {
			// Ignore reinitialization if same context passed in.
			if (this.applicationContext != context) {
				throw new ApplicationContextException(
						"Cannot reinitialize with different application context: current one is [" +
						this.applicationContext + "], passed-in one is [" + context + "]");
			}
		}
}