Unable to autowire the service inside my authentication filter in Spring

Question

I am trying to authenticate user by token, But when i try to auto wire one my services inside the AuthenticationTokenProcessingFilter i get null pointer excepti

Answer 1

If your filter class extends GenericFilterBean you can get a reference to a bean in your app context this way:

public void initFilterBean() throws ServletException {

@Override
public void initFilterBean() throws ServletException {

        WebApplicationContext webApplicationContext =
            WebApplicationContextUtils.getWebApplicationContext(getServletContext());
        //reference to bean from app context
        yourBeanToInject = webApplicationContext.getBean(yourBeanToInject.class);

        //do something with your bean
        propertyValue = yourBeanToInject.getValue("propertyName");
}

And here is less explicit way for those who doesn't like hardcoding bean names or need to inject more than one bean reference into the filter:

@Autowired
private YourBeanToInject yourBeanToInject;

@Override
public void initFilterBean() throws ServletException{

    SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, getServletContext());

    //do something with your bean
    propertyValue = yourBeanToInject.getValue("propertyName");
}