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

IturPablo picture IturPablo · Oct 24, 2011 · Viewed 44.5k times · Source

I have defined a javax.servlet.Filter and I have Java class with Spring annotations.

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Bean;

@Configuration
public class SocialConfig {

    // ...

    @Bean
    public UsersConnectionRepository usersConnectionRepository() {
        // ...
    }
}

I want to get the bean UsersConnectionRepository in my Filter, so I tried the following:

public void init(FilterConfig filterConfig) throws ServletException {
    UsersConnectionRepository bean = (UsersConnectionRepository) filterConfig.getServletContext().getAttribute("#{connectionFactoryLocator}");
}

But it always returns null. How can I get a Spring bean in a Filter?

Answer

Bozho picture Bozho · Oct 24, 2011

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)