java - Local jars are not included in class path (`<scope>system</scope>`)

Question

I am trying to build my application using maven and eclipse. I have dependencies on 3rd party jars which are on my local machine. here is my pom.xml

<dependency>
    <groupId>sourceforge.net</groupId>
   <artifactId>zipdiff</artifactId>
   <version>0.4</version>
   <scope>system</scope>
   <systemPath>C:/gelcap/lib/zipdiff-0.4.jar</systemPath>
</dependency>

<dependency>
    <groupId>log4j</groupId>
   <artifactId>log4j</artifactId>
   <version>1.2.11</version>
</dependency>

when i run mvn : install it creates war file for my project. But problem is it does not include zipdiff.jar file to the web-inf/lib folder it only includes the files which are downloaded. I need to include copy the files from my local system also but maven ignores them. I have not got any thought why it is happening why maven is not including files with system scope to my war file. Please give me any idea how this problem can be resolved. Thanks in advance

Answer 1

With "system" scope, the container is expected to provide the artefact. From the maven docs:

provided

This is much like compile, but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided because the web container provides those classes. This scope is only available on the compilation and test classpath, and is not transitive.

[...]

system

This scope is similar to provided except that you have to provide the JAR which contains it explicitly. The artifact is always available and is not looked up in a repository.

By using a system scope, you are indicating to the war plugin that the container will provide this dependency. Since this is not what you are intending to do, the simplest solution is to put the artefact in a repository, either your local maven repository, or your own maven repo on your intranet, if you have one.

The install:install-file goal can be used to install a single file (without POM) to your local repository. After doing this, change the dependency type to "compile" and remove the "systemPath" element.

In my day job, we use Nexus to manage a company-wide repository on our intranet. You can have separate repositories for your own artefacts, vs third party artefacts. Nexus also acts as a proxy, caching artefacts from external repositories, speeding up the build quite a bit. This means that only the developer that uses a new dependency that is not available in the other repos has to upload - after that, all the other devs can use it - they can checkout from SCM and build without worrying about where the dependencies are located.