Difference between jar and war in Java

Question

What is the difference between a .jar and a .war file?
Is it only the file extension or is there something more?

Solution 1

From Java Tips: Difference between ear jar and war files:

These files are simply zipped files using the java jar tool. These files are created for different purposes. Here is the description of these files:

• .jar files: The .jar files contain libraries, resources and accessories files like property files.

• .war files: The war file contains the web application that can be deployed on any servlet/jsp container. The .war file contains jsp, html, javascript and other files necessary for the development of web applications.

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Official Sun/Oracle descriptions:

• The J2EETM Tutorial: Web Application Archives
• The Java Archive (JAR) File Format: The Basics

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Wikipedia articles:

• WAR file format (Sun)
• JAR file

Solution 2

WAR stands for Web application ARchive

JAR stands for Java ARchive

Solution 3

A .war file has a specific structure in terms of where certain files will be. Other than that, yes, it's just a .jar.

Solution 4

You add web components to a J2EE application in a package called a web application archive (WAR), which is a JAR similar to the package used for Java class libraries. A WAR usually contains other resources besides web components, including:

• Server-side utility classes (database beans, shopping carts, and so on).
• Static web resources (HTML, image, and sound files, and so on)
• Client-side classes (applets and utility classes)

A WAR has a specific hierarchical directory structure. The top-level directory of a WAR is the document root of the application. The document root is where JSP pages, client-side classes and archives, and static web resources are stored.

(source)

So a .war is a .jar, but it contains web application components and is laid out according to a specific structure. A .war is designed to be deployed to a web application server such as Tomcat or Jetty or a Java EE server such as JBoss or Glassfish.

Solution 5

A .war file is a Web Application Archive which runs inside an application server while a .jar is Java Application Archive that runs a desktop application on a user's machine.

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