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

Question

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 1

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)