As we all know that struts and spring are frame works written in Java. Struts developed by Apache foundation, Struts is accepted by many companies as it is very easy for them to develop a web application using Struts. Struts 1.2 is industry accepted version.
Spring MVC also a frame work after struts spring is more popular among industry applications. At present Spring has more opportunities than Struts. But I would recommend to learn both frame works. Both are similar in some aspects.