package org.slf4j.log4j12;
   
   import org.apache.log4j.Level;
   import org.slf4j.ILoggerFactory;
   import org.slf4j.IMarkerFactory;
   import org.slf4j.helpers.BasicMarkerFactory;
   import org.slf4j.helpers.Util;
   import org.slf4j.spi.MDCAdapter;
   import org.slf4j.spi.SLF4JServiceProvider;
  
  public class Log4j12ServiceProvider implements SLF4JServiceProvider {
  
      /**
       * Declare the version of the SLF4J API this implementation is compiled against. 
       * The value of this field is modified with each major release. 
       */
      // to avoid constant folding by the compiler, this field must *not* be final
      public static String REQUESTED_API_VERSION = "2.0.99"; // !final
  
      private ILoggerFactory loggerFactory;
      private IMarkerFactory markerFactory;
      private MDCAdapter mdcAdapter;
  
      public Log4j12ServiceProvider() {
          try {
              @SuppressWarnings("unused")
              Level level = Level.TRACE;
          } catch (NoSuchFieldError nsfe) {
              Util.report("This version of SLF4J requires log4j version 1.2.12 or later. See also http://www.slf4j.org/codes.html#log4j_version");
          }
      }
  
      @Override
      public void initialize() {
          loggerFactory = new Log4jLoggerFactory();
          markerFactory = new BasicMarkerFactory();
          mdcAdapter = new Log4jMDCAdapter();
      }
  
      @Override
      public ILoggerFactory getLoggerFactory() {
          return loggerFactory;
      }
  
  
      @Override
      public IMarkerFactory getMarkerFactory() {
          return markerFactory;
      }
  
  
      @Override
      public MDCAdapter getMDCAdapter() {
          return mdcAdapter;
      }
  
      @Override
      public String getRequestedApiVersion() {
          return REQUESTED_API_VERSION;
      }
  }