implementing ApplicationContextAware - ApplicationContext is NULL

Question

I\'m programming a Tomcat application which serves as a proxy for some internal services.

I\'ve switched my Spring project from a mixed XML and annotation-based conf

Answer 1

As the application context is correctly injected in your controller, I assume that Spring is correctly initialized. But your filters are declared as raw filters, not as spring beans, so the spring annotations are ignored on them.

You have two ways to get access to the application context:

1. a raw filter (not Spring enabled) can get access to the root application context with WebApplicationContext WebApplicationContextUtils.getWebApplicationContext(ServletContext sc). For example, you could change your init method:

   @Override
   public void init(FilterConfig filterConfig)    
   {
       ServletContex sc = filterConfig.getServletContext();
       appContext = WebApplicationContextUtils.getWebApplicationContext(sc);
       logger.debug("Filter {} initialisiert. App-Context: {} {}", this.getClass().getName(),appContext.hashCode(), appContext);
   }
   

2. you can also use a DelegatingFilterProxy to effectively use beans as filters:

   Change add filter to:

   private void addFilters(ServletContext container) {
       FilterRegistration.Dynamic registration
               = container.addFilter("u3rAuthentication", DelegatingFilterProxy.class);
       registration.addMappingForUrlPatterns(null, false, "/entry/*");
   
       registration = container.addFilter("responseXmlFilter", DelegatingFilterProxy.class);
       registration.addMappingForUrlPatterns(null, false, "/entry/*");
   }
   

   add filter beans in your root context:

   @Bean
   public UserDbAuthenticationFilter u3rAuthentication() { 
       return new UserDbAuthenticationFilter();
   }
   
   @Bean
   public ResponseTextXmlFilter responseXmlFilter() { 
       return new ResponseTextXmlFilter();
   }
   

   the init method will no longer be called, but this would work:

   @PostConstruct
   public void filterInit() throws ServletException
   {
       logger.debug("Filter {} initialisiert. App-Context: {} {}", this.getClass().getName(),appContext.hashCode(), appContext);
   }