content: /*
   * Copyright 2007 Yusuke Yamamoto
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package twitter4j;
  
  /**
   * @author Yusuke Yamamoto - yusuke at mac.com
   * @since Twitter4J 2.1.0
   */
  public abstract class Logger {
      private static final LoggerFactory LOGGER_FACTORY;
      private static final String LOGGER_FACTORY_IMPLEMENTATION = "twitter4j.loggerFactory";
      private static final String LOGGER_FACTORY_IMPLEMENTATION_ENV = "twitter4j_loggerFactory";
  
      static {
          LoggerFactory loggerFactory = null;
          // -Dtwitter4j.debug=true -Dtwitter4j.loggerFactory=twitter4j.StdOutLoggerFactory
          String loggerFactoryImpl = System.getProperty(LOGGER_FACTORY_IMPLEMENTATION);
          if (loggerFactoryImpl == null) {
              loggerFactoryImpl = System.getenv(LOGGER_FACTORY_IMPLEMENTATION_ENV);
          }
          if (loggerFactoryImpl != null) {
              loggerFactory = getLoggerFactoryIfAvailable(loggerFactoryImpl, loggerFactoryImpl);
          }
  
          if (loggerFactoryImpl != null) {
              loggerFactory = getLoggerFactoryIfAvailable(loggerFactoryImpl, loggerFactoryImpl);
          }
          // use SLF4J if it's found in the classpath
          if (null == loggerFactory) {
              loggerFactory = getLoggerFactoryIfAvailable("org.slf4j.impl.StaticLoggerBinder", "twitter4j.SLF4JLoggerFactory");
          }
          // otherwise, use commons-logging if it's found in the classpath
          if (null == loggerFactory) {
              loggerFactory = getLoggerFactoryIfAvailable("org.apache.commons.logging.Log", "twitter4j.CommonsLoggingLoggerFactory");
          }
          // otherwise, use log4j if it's found in the classpath
          if (null == loggerFactory) {
              loggerFactory = getLoggerFactoryIfAvailable("org.apache.log4j.Logger", "twitter4j.Log4JLoggerFactory");
          }
          // on Google App Engine, use java.twitter4j.JULogger
          if (null == loggerFactory) {
              loggerFactory = getLoggerFactoryIfAvailable("com.google.appengine.api.urlfetch.URLFetchService", "twitter4j.JULLoggerFactory");
          }
          // otherwise, use the default logger
          LOGGER_FACTORY = loggerFactory;
  
      }
  
      private static LoggerFactory getLoggerFactoryIfAvailable(String checkClassName, String implementationClass) {
          try {
              Class.forName(checkClassName);
              return (LoggerFactory) Class.forName(implementationClass).newInstance();
          } catch (ClassNotFoundException ignore) {
          } catch (InstantiationException e) {
              throw new AssertionError(e);
          } catch (SecurityException ignore) {
              // Unsigned applets are not allowed to access System properties
          } catch (IllegalAccessException e) {
              throw new AssertionError(e);
          }
          return null;
      }
  
      /**
       * Returns a Logger instance associated with the specified class.
       *
       * @param clazz class
       * @return logger instance
       */
      public static Logger getLogger(Class<?> clazz) {
          return LOGGER_FACTORY.getLogger(clazz);
      }
  
      /**
       * tests if debug level logging is enabled
       *
       * @return if debug level logging is enabled
       */
      public abstract boolean isDebugEnabled();
  
      /**
       * tests if info level logging is enabled
       *
       * @return if info level logging is enabled
       */
      public abstract boolean isInfoEnabled();
  
      /**
       * tests if warn level logging is enabled
       *
       * @return if warn level logging is enabled
       */
      public abstract boolean isWarnEnabled();
  
      /**
       * tests if error level logging is enabled
       *
       * @return if error level logging is enabled
       */
      public abstract boolean isErrorEnabled();
  
      /**
       * @param message message
       */
      public abstract void debug(String message);
  
      /**
       * @param message  message
       * @param message2 message2
       */
      public abstract void debug(String message, String message2);
  
      /**
       * @param message message
       */
      public abstract void info(String message);
  
      /**
       * @param message  message
       * @param message2 message2
       */
      public abstract void info(String message, String message2);
  
      /**
       * @param message message
       */
      public abstract void warn(String message);
  
      /**
       * @param message  message
       * @param message2 message2
       */
      public abstract void warn(String message, String message2);
  
      /**
       * @param message  message
       * @param th      throwable
       */
      public abstract void warn(String message, Throwable th);
  
      /**
       * @param message message
       */
      public abstract void error(String message);
  
      /**
       * @param message message
       * @param th      throwable
       */
      public abstract void error(String message, Throwable th);
  
  }
  