If we define webapp specific servlet filters in WAR's own web.xml, then the order of execution of the filters will be the same as the order in which they are defined in the web.xml.
But, if we define those filters using @WebFilter annotation, what is the order of execution of filters, and how can we determine the order of execution?
This question is related to
servlets
jakarta-ee
web.xml
servlet-filters
order-of-execution
You can indeed not define the filter execution order using @WebFilter annotation. However, to minimize the web.xml usage, it's sufficient to annotate all filters with just a filterName so that you don't need the <filter> definition, but just a <filter-mapping> definition in the desired order.
For example,
@WebFilter(filterName="filter1")
public class Filter1 implements Filter {}
@WebFilter(filterName="filter2")
public class Filter2 implements Filter {}
with in web.xml just this:
<filter-mapping>
<filter-name>filter1</filter-name>
<url-pattern>/url1/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>filter2</filter-name>
<url-pattern>/url2/*</url-pattern>
</filter-mapping>
If you'd like to keep the URL pattern in @WebFilter, then you can just do like so,
@WebFilter(filterName="filter1", urlPatterns="/url1/*")
public class Filter1 implements Filter {}
@WebFilter(filterName="filter2", urlPatterns="/url2/*")
public class Filter2 implements Filter {}
but you should still keep the <url-pattern> in web.xml, because it's required as per XSD, although it can be empty:
<filter-mapping>
<filter-name>filter1</filter-name>
<url-pattern />
</filter-mapping>
<filter-mapping>
<filter-name>filter2</filter-name>
<url-pattern />
</filter-mapping>
Regardless of the approach, this all will fail in Tomcat until version 7.0.28 because it chokes on presence of <filter-mapping> without <filter>. See also Using Tomcat, @WebFilter doesn't work with <filter-mapping> inside web.xml
The Servlet 3.0 spec doesn't seem to provide a hint on how a container should order filters that have been declared via annotations. It is clear how about how to order filters via their declaration in the web.xml file, though.
Be safe. Use the web.xml file order filters that have interdependencies. Try to make your filters all order independent to minimize the need to use a web.xml file.
import org.springframework.core.Ordered;
public class MyFilter implements Filter, Ordered {
@Override
public void init(FilterConfig filterConfig) {
// do something
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
// do something
}
@Override
public void destroy() {
// do something
}
@Override
public int getOrder() {
return -100;
}
}
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@Configuration
@ComponentScan
public class MyAutoConfiguration {
@Bean
public MyFilter myFilter() {
return new MyFilter();
}
}
Source: Stackoverflow.com