I would like to use Maven-shade-plugin to create uber-jar. But when I call mvn package
command Maven reports that there are some overlapping classes. I am attaching all problematic overlapps, some of them are caused because older and new verion of a library (Log4J), but some of them seems to have the same classes - e.g. javax.mail and mailapi/smtp/imap et cetera.
What is the best to do in this situation? Is there some key how to decide which overlapping is safe to ignore a which needs to be correct?
- mailapi-1.4.3.jar, javax.mail-1.5.0.jar define 166 overlappping classes
- spring-2.5.6.SEC03.jar, spring-tx-3.1.4.RELEASE.jar define 176 overlappping classes:
- spring-beans-3.1.4.RELEASE.jar, spring-2.5.6.SEC03.jar define 283 overlappping classes:
- slf4j-log4j12-1.7.5.jar, slf4j-impl-2.0-beta2.jar define 3 overlappping classes:
- spring-2.5.6.SEC03.jar, spring-context-support-3.1.4.RELEASE.jar define 55 overlappping classes:
- aopalliance-1.0.jar, spring-2.5.6.SEC03.jar define 9 overlappping classes:
- imap-1.5.0.jar, javax.mail-1.5.0.jar define 87 overlappping classes:
- commons-logging-api-1.1.jar, commons-logging-1.1.3.jar define 19 overlappping classes:
- spring-2.5.6.SEC03.jar, spring-core-3.1.4.RELEASE.jar define 161 overlappping classes:
- spring-2.5.6.SEC03.jar, spring-context-3.1.4.RELEASE.jar define 326 overlappping classes:
- log4j12-api-2.0-beta3.jar, log4j-1.2.17.jar define 23 overlappping classes:
- spring-aop-3.1.4.RELEASE.jar, spring-2.5.6.SEC03.jar define 237 overlappping classes:
- spring-jdbc-3.1.4.RELEASE.jar, spring-2.5.6.SEC03.jar define 239 overlappping classes:
- quartz-1.8.6.jar, quartz-jobs-2.2.1.jar define 15 overlappping classes:
- smtp-1.5.0.jar, javax.mail-1.5.0.jar define 17 overlappping classes:
- spring-asm-3.1.4.RELEASE.jar, spring-2.5.6.SEC03.jar define 31 overlappping classes:
EDIT: this application "A" uses as a Maven dependency my another Java application - I'll call this app "B". This B application uses javax.mail ver 1.5.1. This library uses the first application too. But when I call mvn package command, Maven notices that javax.mail-api-1.5.1.jar, javax.mail-1.5.1.jar define 135 overlappping classes
.
Is this problem and if so, how to solve it or can I ignore it?
The ManifestResourceTransformer allows existing entries in the MANIFEST to be replaced and new entries added.
An uber-JAR—also known as a fat JAR or JAR with dependencies—is a JAR file that contains not only a Java program, but embeds its dependencies as well. This means that the JAR functions as an “all-in-one” distribution of the software, without needing any other Java code.
A shaded jar aka uber-jar aka fat jar will by default contain every dependency that is required to run the Java application so that no additional dependency is required to be in the classpath. You only need the correct Java version to run your application.
Sometimes it is necessary to relocate artifacts in the repository. One example of that is when a project moves from one groupId to a different groupId. Making changes to the repository can have far reaching consequences. So it is best to get it right the first time, hence this guide.
The first thing to do is remove as many of the obvious causes of overlapping classes as you can. For instance:
It's unlikely that you will need to retain conflicting versions of the classes in the shaded jar. If you do, the shade plugin also allows the relocation of classes, as described at http://maven.apache.org/plugins/maven-shade-plugin/examples/class-relocation.html
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