What is the difference between a .jar and a .war file?
Is it only the file extension or is there something more?
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14 Answers
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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.
Official Sun/Oracle descriptions:
Wikipedia articles:
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A .war file has a specific structure in terms of where certain files will be. Other than that, yes, it's just a .jar.
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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.
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.jar and .war are both zipped archived files. Both can have the optional META-INF/MANIFEST.MF manifest file which hold informative information like versioning, and instructional attributes like classpath and main-class for the JVM that will execute it.
.war file - Web Application Archive intended to be execute inside a 'Servlet Container' and may include other jar files (at WEB-INF/lib directory) compiled classes (at WEB-INF/classes (servlet goes there too)) .jsp files images, files etc. All WAR content that is there in order to create a self-contained module.
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A JAR file extension is .jar and is created with jar command from command prompt (like javac command is executed). Generally, a JAR file contains Java related resources like libraries, classes etc.JAR file is like winzip file except that Jar files are platform independent.
A WAR file is simply a JAR file but contains only Web related Java files like Servlets, JSP, HTML.
To execute a WAR file, a Web server or Web container is required, for example, Tomcat or Weblogic or Websphere. To execute a JAR file, simple JDK is enough.
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War -
distribute Java-based web applications. A WAR has the same file structure as a JAR file, which is a single compressed file that contains multiple files bundled inside it.
Jar -
The .jar files contain libraries, resources and accessories files like property files.
WAR files are used to combine JSPs, servlets, Java class files, XML files, javascript libraries, JAR libraries, static web pages, and any other resources needed to run the application.
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JAR files allow to package multiple files in order to use it as a library, plugin, or any kind of application. On the other hand, WAR files are used only for web applications.
JAR can be created with any desired structure. In contrast, WAR has a predefined structure with WEB-INF and META-INF directories.
A JAR file allows Java Runtime Environment (JRE) to deploy an entire application including the classes and the associated resources in a single request. On the other hand, a WAR file allows testing and deploying a web application easily.
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