Maven projects can use different packaging methods, such as POM, JAR and WAR, which determine the type and purpose of the product generated after the project is built. The following are the differences between these packaging methods:
1. **POM (Project Object Model):** The POM packaging method does not actually generate an executable build product. It is a collection of metadata and configuration for a project, used to manage the project's structure, dependencies, build settings, etc. POM projects are used to manage dependencies and inheritance relationships between modules, but do not generate actual executable files themselves.
2. **JAR (Java Archive): ** The JAR packaging method is used to create executable JAR files for Java applications. A JAR file contains the project's compiled class files and other resources, and can be executed directly by the Java Virtual Machine (JVM). JAR files are for stand-alone Java applications or libraries that can be run from the command line or by other means.
3. **WAR (Web Application Archive):** The WAR packaging method is used to create a deployable WAR file for a Web application. The WAR file contains all the resources required by the Web application, including JSP files, HTML files, Servlet classes, configuration files, etc. It is suitable for deployment into Java web containers (such as Tomcat, Jetty) to provide web services.
To sum up, the POM packaging method is used for project configuration and management , and does not generate executable products ; JAR packaging method: used to create independent executable Java applications ; WAR packaging method: used to create deployable Java Web applications .