How to exclude a dependency from parent's project in Maven?

Question

For example, I have 2 Maven projects. One is \"project-parent\". The other is \"project-child\". Obviously, \"project-child\" is the sub project of \"project-parent\".

Answer 1

I have met the same question just like you. In my project, let call the parent pom is parent.pom. parent defined the log4j, slf4j like this:

       
            org.slf4j
            slf4j-api
            ${slf4j-api.version}
        
        
            log4j
            log4j
            ${log4j.version}
        
        
            org.slf4j
            jcl-over-slf4j
            ${slf4j-api.version}
        

        
            org.slf4j
            slf4j-log4j12
            ${slf4j-log4j12.version}
        

child project invoke some dependency in child.pom. But I don't want the log4j-1.2.x dependency and want to increase the version of slf4j.

So. I add the dependency of parent

        parent
        myartifactId
        ${my parent version}

and use exclusions to remove the log4j

        parent
        myartifactId
        ${my parent version}
        
            
                log4j
                log4j
            
        

and explicitly add the slf4j and log4j2's dependency in child pom

 
        org.slf4j
        slf4j-api
        1.7.6
    
    
        org.apache.logging.log4j
        log4j-slf4j-impl
        2.8.2
    
    
        org.apache.logging.log4j
        log4j-api
        2.8.2
    

    
        org.apache.logging.log4j
        log4j-core
        2.8.2
    

    
        com.lmax
        disruptor
        3.3.4
    

then use mvn dependency:tree to show the dependency list, still see the log4j

[INFO] +- org.apache.kafka:kafka_2.10:jar:0.8.2.0:compile
[INFO] |  +- com.yammer.metrics:metrics-core:jar:2.2.0:compile
[INFO] |  +- org.scala-lang:scala-library:jar:2.10.4:compile
[INFO] |  +- org.apache.zookeeper:zookeeper:jar:3.4.6:compile
[INFO] |  |  +- org.slf4j:slf4j-log4j12:jar:1.7.5:compile
[INFO] |  |  +- log4j:log4j:jar:1.2.17:compile

well, let's add the exclusions on that dependency...remove this guy.

    
        org.apache.kafka
        kafka-clients
        0.10.1.1
        
            
                log4j
                log4j
            
        
    

then run the command again to check the dependency list. OK! clear~

Hope that can help you :>