log4j-over-slf4j/src/main/java/org/apache/log4j/Category.java

/*
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * 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 org.apache.log4j;

import org.slf4j.LoggerFactory;
import org.slf4j.Marker;
import org.slf4j.MarkerFactory;
import org.slf4j.spi.LocationAwareLogger;

/**
 * <p>
 * This class is a minimal implementation of the original
 * <code>org.apache.log4j.Category</code> class (as found in log4j 1.2) by
 * delegation of all calls to a {@link org.slf4j.Logger.Logger} instance.
 * </p>
 * 
 * <p>
 * Log4j's <code>trace</code>, <code>debug()</code>, <code>info()</code>,
 * <code>warn()</code>, <code>error()</code> printing methods are directly
 * mapped to their SLF4J equivalents. Log4j's <code>fatal()</code> printing
 * method is mapped to SLF4J's <code>error()</code> method with a FATAL
 * marker.
 * 
 * @author S&eacute;bastien Pennec
 * @author Ceki G&uuml;lc&uuml;
 */
public class Category {

  private static final String CATEGORY_FQCN = Category.class.getName();

  private String name;

  protected org.slf4j.Logger slf4jLogger;
  private org.slf4j.spi.LocationAwareLogger locationAwareLogger;

  private static Marker FATAL_MARKER = MarkerFactory.getMarker("FATAL");

  Category(String name) {
    this.name = name;
    slf4jLogger = LoggerFactory.getLogger(name);
    if (slf4jLogger instanceof LocationAwareLogger) {
      locationAwareLogger = (LocationAwareLogger) slf4jLogger;
    }
  }

  public static Category getInstance(Class clazz) {
    return Log4jLoggerFactory.getLogger(clazz.getName());
  }

  public static Category getInstance(String name) {
    return Log4jLoggerFactory.getLogger(name);
  }

  /**
   * Returns the obvious.
   * 
   * @return
   */
  public String getName() {
    return name;
  }

  /**
   * Return the level in effect for this category/logger.
   * 
   * <p>
   * The result is computed by simulation.
   * 
   * @return
   */
  public Level getEffectiveLevel() {
    if (slf4jLogger.isTraceEnabled()) {
      return Level.TRACE;
    }
    if (slf4jLogger.isDebugEnabled()) {
      return Level.DEBUG;
    }
    if (slf4jLogger.isInfoEnabled()) {
      return Level.INFO;
    }
    if (slf4jLogger.isWarnEnabled()) {
      return Level.WARN;
    }
    return Level.ERROR;
  }

  /**
   * Returns the assigned {@link Level}, if any, for this Category. This
   * implementation always returns null.
   * 
   * @return Level - the assigned Level, can be <code>null</code>.
   */
  final public Level getLevel() {
    return null;
  }

  /**
   * @deprecated Please use {@link #getLevel} instead.
   */
  final public Level getPriority() {
    return null;
  }

  /**
   * Delegates to {@link org.slf4j.Logger#isDebugEnabled} method in SLF4J
   */
  public boolean isDebugEnabled() {
    return slf4jLogger.isDebugEnabled();
  }

  /**
   * Delegates to {@link org.slf4j.Logger#isInfoEnabled} method in SLF4J
   */
  public boolean isInfoEnabled() {
    return slf4jLogger.isInfoEnabled();
  }

  /**
   * Delegates tob {@link org.slf4j.Logger#isWarnEnabled} method in SLF4J
   */
  public boolean isWarnEnabled() {
    return slf4jLogger.isWarnEnabled();
  }

  /**
   * Delegates to {@link org.slf4j.Logger#isErrorEnabled} method in SLF4J
   */
  public boolean isErrorEnabled() {
    return slf4jLogger.isErrorEnabled();
  }

  /**
   * Determines whether the priority passed as parameter is enabled in the
   * underlying SLF4J logger. Each log4j priority is mapped directly to its
   * SLF4J equivalent, except for FATAL which is mapped as ERROR.
   * 
   * @param p
   *                the priority to check against
   * @return true if this logger is enabled for the given level, false
   *         otherwise.
   */
  public boolean isEnabledFor(Priority p) {
    switch (p.level) {
    case Level.TRACE_INT:
      return slf4jLogger.isTraceEnabled();
    case Level.DEBUG_INT:
      return slf4jLogger.isDebugEnabled();
    case Level.INFO_INT:
      return slf4jLogger.isInfoEnabled();
    case Level.WARN_INT:
      return slf4jLogger.isWarnEnabled();
    case Level.ERROR_INT:
      return slf4jLogger.isErrorEnabled();
    case Priority.FATAL_INT:
      return slf4jLogger.isErrorEnabled();
    }
    return false;
  }

  void differentiatedLog(Marker marker, String fqcn, int level, Object message,
      Throwable t) {
    String m = convertToString(message);
    if (locationAwareLogger != null) {
      locationAwareLogger.log(marker, fqcn, level, m, t);
    } else {
      switch (level) {
      case LocationAwareLogger.TRACE_INT:
        slf4jLogger.trace(marker, m);
        break;
      case LocationAwareLogger.DEBUG_INT:
        slf4jLogger.debug(marker, m);
        break;
      case LocationAwareLogger.INFO_INT:
        slf4jLogger.info(marker, m);
        break;
      case LocationAwareLogger.WARN_INT:
        slf4jLogger.warn(marker, m);
        break;
      case LocationAwareLogger.ERROR_INT:
        slf4jLogger.error(marker, m);
        break;
      }
    }
  }

  /**
   * Delegates to {@link org.slf4j.Logger#debug(String)} method of SLF4J.
   */
  public void debug(Object message) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.DEBUG_INT,
        message, null);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#debug(String,Throwable)} method in
   * SLF4J.
   */
  public void debug(Object message, Throwable t) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.DEBUG_INT,
        message, t);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#info(String)} method in SLF4J.
   */
  public void info(Object message) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.INFO_INT,
        message, null);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#info(String,Throwable)} method in
   * SLF4J.
   */
  public void info(Object message, Throwable t) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.INFO_INT,
        message, t);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#warn(String)} method in SLF4J.
   */
  public void warn(Object message) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.WARN_INT,
        message, null);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#warn(String,Throwable)} method in
   * SLF4J.
   */
  public void warn(Object message, Throwable t) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.WARN_INT,
        message, t);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#error(String)} method in SLF4J.
   */
  public void error(Object message) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.ERROR_INT,
        message, null);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#error(String,Throwable)} method in
   * SLF4J.
   */
  public void error(Object message, Throwable t) {
    differentiatedLog(null, CATEGORY_FQCN, LocationAwareLogger.ERROR_INT,
        message, t);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#error(String)} method in SLF4J.
   */
  public void fatal(Object message) {
    differentiatedLog(FATAL_MARKER, CATEGORY_FQCN,
        LocationAwareLogger.ERROR_INT, message, null);
  }

  /**
   * Delegates to {@link org.slf4j.Logger#error(String,Throwable)} method in
   * SLF4J. In addition, the call is marked with a marker named "FATAL".
   */
  public void fatal(Object message, Throwable t) {
    differentiatedLog(FATAL_MARKER, CATEGORY_FQCN,
        LocationAwareLogger.ERROR_INT, message, t);
  }

  
  public void log(String FQCN, Priority p, Object msg, Throwable t) {
    int levelInt = priorityToLevelInt(p);
    if (locationAwareLogger != null) {
      locationAwareLogger.log(null, FQCN, levelInt, convertToString(msg), t);
    } else {
      throw new UnsupportedOperationException("The logger [" + slf4jLogger
          + "] does not seem to be location aware.");
    }
  }

  public void log(Priority p, Object message, Throwable t) {
    int levelInt = priorityToLevelInt(p);
    differentiatedLog(null, CATEGORY_FQCN, levelInt,
        message, t);
  }

  public void log(Priority p, Object message) {
    int levelInt = priorityToLevelInt(p);
    differentiatedLog(null, CATEGORY_FQCN, levelInt,
        message, null);
  }


  private int priorityToLevelInt(Priority p) {
    switch (p.level) {
    case Level.TRACE_INT:
      return LocationAwareLogger.TRACE_INT;
    case Priority.DEBUG_INT:
      return LocationAwareLogger.DEBUG_INT;
    case Priority.INFO_INT:
      return LocationAwareLogger.INFO_INT;
    case Priority.WARN_INT:
      return LocationAwareLogger.WARN_INT;
    case Priority.ERROR_INT:
      return LocationAwareLogger.ERROR_INT;
    case Priority.FATAL_INT:
      return LocationAwareLogger.ERROR_INT;
    default:
      throw new IllegalStateException("Unknown Priority " + p);
    }
  }

  protected final String convertToString(Object message) {
    if (message == null) {
      return (String) message;
    } else {
      return message.toString();
    }
  }

}