Maven: remove a single transitive dependency

Question

My project includes a jar file because it is listed as a transitive dependency.

However, I have verified not only that I don't need it but it causes problems because a class inside the jar files shadows a class I need in another jar file.

I do how leave out a single jar file from my transitive dependencies?

Answer 1

You can do this by explicitly excluding the problematic artifact. Take the dependency that includes the problem and mark it to be excluded:

From the maven website:

<dependency>
  <groupId>group-a</groupId>
  <artifactId>artifact-a</artifactId>
  <version>1.0</version>
  <exclusions>
    <exclusion>
      <groupId>group-c</groupId>
      <artifactId>excluded-artifact</artifactId>
    </exclusion>
  </exclusions>
</dependency>

Answer 2

You can exclude a dependency in the following manner:

        <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring</artifactId>
                <version>2.5.6</version>
                <exclusions>
                        <exclusion>
                                <groupId>commons-logging</groupId>
                                <artifactId>commons-logging</artifactId>
                        </exclusion>
                </exclusions>
        </dependency>

Answer 3

The correct way is to use the exclusions mechanism, however sometimes you may prefer to use the following hack instead to avoid adding a large number of exclusions when lots of artifacts have the same transitive dependency which you wish to ignore. Rather than specifying an exclusion, you define an additional dependency with a scope of "provided". This tells Maven that you will manually take care of providing this artifact at runtime and so it will not be packaged. For instance:

    <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring</artifactId>
            <version>2.5.6</version>
    </dependency>
    <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.1.1</version>
            <scope>provided</scope>
    </dependency>

Side effect: you must specify a version of the artifact-to-be-ignored, and its POM will be retrieved at build-time; this is not the case with regular exclusions. This might be a problem for you if you run your private Maven repository behind a firewall.