Problem statement:
What is the Adobe recommended way to create Filters?
Requirement:
Create the Filters to chain the requests and add logs
Introduction:
- A filter is an object that performs filtering tasks on either the request to a resource (a servlet or static content), or on the response from a resource, or both.
- Filters perform filtering in the doFilter method. Every Filter has access to a FilterConfig object from which it can obtain its initialization parameters, and a reference to the ServletContext which it can use, for example, to load resources needed for filtering tasks.
- Filters are configured in the deployment descriptor of a web application.
Create Component Service with Filter class and implement a Filter class
Provide service description, ranking and vendor for the filter
Override doFilter method and chain the requests
package com.mysite.core.filters;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.engine.EngineConstants;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.propertytypes.ServiceDescription;
import org.osgi.service.component.propertytypes.ServiceRanking;
import org.osgi.service.component.propertytypes.ServiceVendor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Simple servlet filter component that logs incoming requests.
*/
@Component(service = Filter.class,
property = {
EngineConstants.SLING_FILTER_SCOPE + "=" + EngineConstants.FILTER_SCOPE_REQUEST,
})
@ServiceDescription("Demo to filter incoming requests")
@ServiceRanking(-700)
@ServiceVendor("Adobe")
public class LoggingFilter implements Filter {
private final Logger logger = LoggerFactory.getLogger(getClass());
@Override
public void doFilter(final ServletRequest request, final ServletResponse response,
final FilterChain filterChain) throws IOException, ServletException {
final SlingHttpServletRequest slingRequest = (SlingHttpServletRequest) request;
logger.debug("request for {}, with selector {}", slingRequest
.getRequestPathInfo().getResourcePath(), slingRequest
.getRequestPathInfo().getSelectorString());
filterChain.doFilter(request, response);
}
@Override
public void init(FilterConfig filterConfig) {
}
@Override
public void destroy() {
}
}
AEM best practices and development guide 