What is the Difference Between JAR and WAR?

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The main difference between a JAR (Java ARchive) and a WAR (Web ARchive) file lies in their intended use and the content they contain:

  • JAR files are used for packaging and distributing standalone Java applications or libraries. They contain Java class files, associated metadata, and resources. JAR files are preferable for deploying Spring Boot applications because they are lightweight and can be embedded with an application server. Examples of JAR contents include libraries, resources, and accessory files like property files.
  • WAR files are used for packaging and distributing web applications. They contain the web application's resources, such as servlets, JSPs, and HTML files, as well as a WEB-INF directory that contains additional metadata, such as the web.xml deployment descriptor. WAR files are typically used for running web applications on a web server and may contain web content like HTML and JSP files, which are not usually found in JAR files.

In summary, JAR files are designed for packaging and distributing standalone Java applications or libraries, while WAR files are used for packaging and distributing web applications.

Comparative Table: JAR vs WAR

The main difference between JAR and WAR files lies in their purpose and functionality. Here is a table comparing the differences between JAR and WAR files:

Feature JAR (Java ARchive) WAR (Web ARchive)
Purpose Used for packaging and distributing standalone Java applications or libraries. Used for packaging and distributing web applications.
Contents Contains Java class files, associated metadata, and resources. Contains web application resources, such as servlets, JSPs, HTML files, and a WEB-INF directory with additional metadata, such as the web.xml deployment descriptor.
Structure Can have any desired structure. Has a predefined structure with WEB-INF and META-INF directories.
Deployment Lightweight and preferable for deploying Spring Boot applications. Typically used for testing and deploying web applications easily.
Use Cases Suitable for running desktop applications on a user's machine. Suitable for running web applications on a server.

In summary, JAR files are used for packaging standalone Java applications or libraries, while WAR files are used for packaging and distributing web applications.