Unable to autowire the service inside my authentication filter in Spring
You cannot use dependency injection from a filter out of the box. Although you are using GenericFilterBean your Servlet Filter is not managed by spring. As noted by the javadocs
This generic filter base class has no dependency on the Spring org.springframework.context.ApplicationContext concept. Filters usually don't load their own context but rather access service beans from the Spring root application context, accessible via the filter's ServletContext (see org.springframework.web.context.support.WebApplicationContextUtils).
In plain English we cannot expect spring to inject the service, but we can lazy set it on the first call. E.g.
public class AuthenticationTokenProcessingFilter extends GenericFilterBean {
private MyServices service;
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
if(service==null){
ServletContext servletContext = request.getServletContext();
WebApplicationContext webApplicationContext = WebApplicationContextUtils.getWebApplicationContext(servletContext);
service = webApplicationContext.getBean(MyServices.class);
}
your code ...
}
}
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");
}
It's an old enough question, but I'll add my answer for those who like me google this issue.
You must inherit your filter from GenericFilterBean
and mark it as a Spring @Component
@Component
public class MyFilter extends GenericFilterBean {
@Autowired
private MyComponent myComponent;
//implementation
}
And then register it in Spring context:
@Configuration
public class MyFilterConfigurerAdapter extends WebMvcConfigurerAdapter {
@Autowired
private MyFilter myFilter;
@Bean
public FilterRegistrationBean myFilterRegistrationBean() {
FilterRegistrationBean regBean = new FilterRegistrationBean();
regBean.setFilter(myFilter);
regBean.setOrder(1);
regBean.addUrlPatterns("/myFilteredURLPattern");
return regBean;
}
}
This properly autowires your components in the filter.
I just made it work by adding
SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
I am unsure why we should do this even when i tried adding explicit qualifier. and now the code looks like
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
@SuppressWarnings("unchecked")
Map<String, String[]> parms = request.getParameterMap();
if (parms.containsKey("token")) {