Add a Servlet Filter in a Spring Boot application
When using Spring Boot
As mentioned in the reference documentation, the only step needed is to declare that filter as a Bean in a configuration class, that's it!
@Configuration
public class WebConfig {
@Bean
public Filter shallowEtagHeaderFilter() {
return new ShallowEtagHeaderFilter();
}
}
When using Spring MVC
You're probably already extending a WebApplicationInitializer
. If not, then you should convert your webapp configuration from a web.xml
file to a WebApplicationInitializer
class.
If your context configuration lives in XML file(s), you can create a class that extends AbstractDispatcherServletInitializer
- if using configuration classes, AbstractAnnotationConfigDispatcherServletInitializer
is the proper choice.
In any case, you can then add Filter registration:
@Override
protected Filter[] getServletFilters() {
return new Filter[] {
new ShallowEtagHeaderFilter();
};
}
Full examples of code-based Servlet container initialization are available in the Spring reference documentation.
A bit late answer.
My solution was to create custom annotation:
import org.springframework.core.annotation.AliasFor;
import org.springframework.stereotype.Component;
// ...
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Component
public @interface Filter {
@AliasFor(annotation = Component.class, attribute = "value")
String value() default "";
}
And then simply apply it to the filter implementations:
@Filter
public class CustomFilter extends AbstractRequestLoggingFilter {
@Override
protected void beforeRequest(HttpServletRequest request, String message) {
logger.debug("before req params:", request.getParameterMap());
}
@Override
protected void afterRequest(HttpServletRequest request, String message) {
logger.debug("after req params:", request.getParameterMap());
}
}
See more: @AliasFor
, Spring custom annotations question