Yes you can. I am using Composer 8.1.102.00.
1) Add the JAr files in
Project_Path\WEB-INF\lib2) Add the below line in the top of backeend code:
<%@page import="Class_Needed_Into_Jar"%>3) Then you can call the class inside the JAR file :
Class_Needed_Into_Jar.Function_Name(Parm1, Parm2, Parm3)