WAR/EAR 概念

In J2EE application, modules are packaged as EAR, JAR and WAR based on their functionality

JAR: EJB modules which contain enterprise java beans (class files) and EJB deployment descriptor are packed as JAR files with .jar extenstion

WAR: Web modules which contain Servlet class files, JSP Files, supporting files, GIF and HTML files are packaged as JAR file with .war (web archive) extension

EAR: All above files (.jar and .war) are packaged as JAR file with .ear (enterprise archive) extension and deployed into Application Server.