[slf4j-user] SLF4J incorrectly determines that Class path contains multiple SLF4J bindings

[Ari Meyer]

Thanks for the confirmation, Ceki.
Ari

Ceki Gulcu wrote:
>
> Hello Ari,
>
> It's a known problem with Weblogic. Please see:
>
>   http://bugzilla.slf4j.org/show_bug.cgi?id=138
>
> Since only Weblogic seems to suffer from this issue, I am leaving it
> open for the time being.
>
> BR
>
> Ari Meyer wrote:
>> Hi,
>>
>> I get this warning in my Eclipse console (using WTP to connect to 
>> WebLogic 10.3):
>>
>> SLF4J: Class path contains multiple SLF4J bindings.
>> SLF4J: Found binding in [zip:C:/Documents and 
>> Settings/Owner.ZEN/.m2/repository/org/slf4j/slf4j-log4j12/1.5.8/slf4j-log4j12-1.5.8.jar!/org/slf4j/impl/StaticLoggerBinder.class] 
>>
>> SLF4J: Found binding in [zip:C:/Documents and 
>> Settings/Owner.ZEN/.m2/repository/org/slf4j/slf4j-log4j12/1.5.8/slf4j-log4j12-1.5.8.jar!/org/slf4j/impl/StaticLoggerBinder.class] 
>>
>> SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an 
>> explanation.
>>
>> Somehow, it's seeing multiple bindings, when they are in fact the 
>> same.  I'm not sure how this is happening (I use Maven and the 
>> maven-eclipse-plugin for configuration).  Referencing this code from 
>> LoggerFactory:
>>
>>  private static String STATIC_LOGGER_BINDER_PATH = 
>> "org/slf4j/impl/StaticLoggerBinder.class";
>>
>>  private static void singleImplementationSanityCheck() {
>>    try {
>>      Enumeration paths = 
>> LoggerFactory.class.getClassLoader().getResources(
>>          STATIC_LOGGER_BINDER_PATH);
>>      List implementationList = new ArrayList();
>>      while (paths.hasMoreElements()) {
>>        URL path = (URL) paths.nextElement();
>>        implementationList.add(path);
>>      }
>>      if (implementationList.size() > 1) {
>>        Util
>>            .reportFailure("Class path contains multiple SLF4J 
>> bindings.");
>>        for(int i = 0; i < implementationList.size(); i++) {
>>          Util.reportFailure("Found binding in 
>> ["+implementationList.get(i)+"]");
>>        }
>>        Util.reportFailure("See " + MULTIPLE_BINDINGS_URL
>>            + " for an explanation.");
>>      }
>>    } catch (IOException ioe) {
>>      Util.reportFailure("Error getting resources from path", ioe);
>>    }
>>  }
>>
>> ... somehow, the Enumeration "paths" must have 2 elements that happen 
>> to be identical -- probably due to my multiple WAR within EAR config 
>> (if I shared my utility JAR at the EAR level, this probably won't 
>> show up).
>>
>> Simple fix: change implementationList from List to Set -- this way 
>> there will be no duplicates.
>>
>> Best regards,
>> Ari
>>
>