HttpClient, Log4J and Maven jar conflicts

Question

I have a Maven POM file using org.apache.httpcomponents wich includes commons-logging (I don't need to include this dependency)

But I need to use Log4J, and it's causing conflicts by including commons-logging JAR and Log4J JARS in same project.

This conflict causing duplicating lines in my log file.

My POM (extract):

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version>2.0-beta5</version>
</dependency>

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.0-beta5</version>
</dependency>

<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.0.1</version>
</dependency>

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.6</version>
</dependency>       

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient-cache</artifactId>
    <version>4.2.3</version>
</dependency>       

I try to put an exclusion tag in org.apache.httpcomponents for commons-loggin, but I got a Runtime error in HttpClient class (no compile error).

What can I do?

Answer 1

Well, my fault!

Seems the specific class logger is stacked with root logger.

First log line is for specific class logger ( the logger called by class name ) and second line (duplicate) is for root logger. This is my log4j XML config:

<loggers>
    <Logger name="cmabreu.sagitarii.teapot.Main" level="debug"> 
        <appender-ref ref="File"/> 
    </Logger>

    <root level="error">
        <appender-ref ref="File" />
    </root>
</loggers>

I need to add additivity="false" for specific logger (cmabreu.sagitarii.teapot.Main), this way it will not stack with root logger.

<Logger name="cmabreu.sagitarii.teapot.Main" level="debug" additivity="false">