How to define servlet filter order of execution using annotations in WAR

Question

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

User · Answer

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

User · Answer

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  lt filter gt  definition  but just a  lt filter-mapping gt  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    lt filter-mapping gt       lt filter-name gt filter1 lt  filter-name gt       lt url-pattern gt  url1   lt  url-pattern gt   lt  filter-mapping gt   lt filter-mapping gt       lt filter-name gt filter2 lt  filter-name gt       lt url-pattern gt  url2   lt  url-pattern gt   lt  filter-mapping gt    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  lt url-pattern gt  in web xml  because it s required as per XSD  although it can be empty    lt filter-mapping gt       lt filter-name gt filter1 lt  filter-name gt       lt url-pattern   gt   lt  filter-mapping gt   lt filter-mapping gt       lt filter-name gt filter2 lt  filter-name gt       lt url-pattern   gt   lt  filter-mapping gt    Regardless of the approach  this all will fail in Tomcat until version 7 0 28 because it chokes on presence of  lt filter-mapping gt  without  lt filter gt   See also Using Tomcat   WebFilter doesn  39 t work with  lt filter-mapping gt  inside web xml

User · Answer

Make the servlet filter implement the spring Ordered interface  Declare the servlet filter bean manually in configuration class       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

[servlets] How to define servlet filter order of execution using annotations in WAR

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