Packaging Application
In general, a java application will have several classes( and thus class files). To run the application, we need all the files to be together. We create a jar or war, which is a zip file which holds all the files (and the libraries in the class path, properties, manifest file etc). The java command can run the jar so the application starts.
WAR vs JAR
.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.
A .war file has a specific structure in terms of where certain files will be.
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.
A .war file is a Web Application Archive which runs inside an application server
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.
Commands
Maven
If included the package plugin for maven and set the configuration, can run
mvn package. This should be build a jar, in the target directory.maven-jar-plugin
Can build an uber jar, which contains all the dependencies in the jar
maven-shade-plugin
maven-assembly-plugin
Manifest file
This states where the main method is, so that the jar can be run
Can use the build tool to generate this for us (ie maven)
which hold informative information like versioning, and instructional attributes like classpath and main-class for the JVM that will execute it.
Links
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