How can I get a Spring bean in a servlet filter?

Try:

UsersConnectionRepository bean = 
  (UsersConnectionRepository)WebApplicationContextUtils.
    getRequiredWebApplicationContext(filterConfig.getServletContext()).
    getBean("usersConnectionRepository");

Where usersConnectionRepository is a name/id of your bean in the application context. Or even better:

UsersConnectionRepository bean = WebApplicationContextUtils.
  getRequiredWebApplicationContext(filterConfig.getServletContext()).
  getBean(UsersConnectionRepository.class);

Also have a look at GenericFilterBean and its subclasses.

Spring have a utility just for this.

In your Filter code, override the init method like this:

public void init(FilterConfig cfg) { 
    super.init(cfg);
    SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
}

Then you just @Inject your beans to that filter, same way as any other bean you would inject.

@Inject
private UsersConnectionRepository repository;

There are three ways:

1. Use WebApplicationContextUtils:

   public void init(FilterConfig cfg) { 
       ApplicationContext ctx = WebApplicationContextUtils
         .getRequiredWebApplicationContext(cfg.getServletContext());
       this.bean = ctx.getBean(YourBeanType.class);
   }
   

2. Using the DelegatingFilterProxy - you map that filter, and declare your filter as bean. The delegating proxy will then invoke all beans that implement the Filter interface.

3. Use @Configurable on your filter. I would prefer one of the other two options though. (This option uses aspectj weaving)