Difference- EAR, JAR and WAR

J2EE defines three types of archives:

• EAR
• WAR
• JAR

When Java applications are deployed, all of the files that constitute the Java app are compressed and packaged into a single file. While compressed files are typically given a .zip extension, the Java community instead uses .ear, .war and .jar files.

 

Under the hood, EAR, JAR and WAR files are all simply zip files that contain the various images, XML files, property files and pieces of Java code that make up a Java application.

• Java Archive (JAR) A JAR file encapsulates one or more Java classes, a manifest, and a descriptor. It also holds generic libraries of Java classes, resources, auxiliary files.  
•  JAR files are the lowest level of archive. JAR files are used in J2EE for packaging EJBs and client-side Java Applications.
• Actually, jar file contains all the .class files of our java project.

Extension- .jar

• Web Archive (WAR) A WAR files are similar to JAR files, except that they are specifically for web applications made from Servlets, JSPs, and supporting classes. These are intended to contain complete Web applications. Web application contain all the web related Technologies like Html,Css, Javascript , Jsp,Servlet ,Xml etc and War file is a compressed form of web application which allows us to make that application portable. Struts and Spring based Web applications may be archived to a WAR.

·                       Extension- .war

• Enterprise Archive (EAR) An EAR file contains all of the components that make up a particular J2EE application. are intended to contain complete enterprise applications. In this context, an enterprise application is defined as a collection of .jar files, resources, classes, and multiple Web applications. An EAR may contain one or more WAR files. EAR files can also contain connector modules packaged as RAR files and Client modules packaged as JAR files.

·                          Extension- .ear

   Summary: 

        

     An EAR file requires a fully Java Platform, Enterprise Edition (Java EE)- or Jakarta Enterprise Edition (EE)-compliant application server, such as WebSphere or JBoss, to run. 

A WAR file only requires a Java EE Web Profile-compliant application server to run.

A JAR file only requires a Java installation.