public static  void configure(String configFilename) 
{
    new PropertyConfigurator().doConfigure(configFilename,
					   LogManager.getLoggerRepository());
}

 public static  void configure(URL configURL) 
{
    new PropertyConfigurator().doConfigure(configURL,
					   LogManager.getLoggerRepository());
}

Read configuration options from url configURL.

 public static  void configure(Properties properties) 
{
    new PropertyConfigurator().doConfigure(properties,
					   LogManager.getLoggerRepository());
}

Read configuration options from properties. See #doConfigure(String, LoggerRepository) for the expected format.

 public static  void configureAndWatch(String configFilename) 
{
    configureAndWatch(configFilename, FileWatchdog.DEFAULT_DELAY);
}

Like #configureAndWatch(String, long) except that the default delay as defined by FileWatchdog#DEFAULT_DELAY is used.

 public static  void configureAndWatch(String configFilename,
    long delay) 
{
    PropertyWatchdog pdog = new PropertyWatchdog(configFilename);
    pdog.setDelay(delay);
    pdog.start();
}

Read the configuration file configFilename if it exists. Moreover, a thread will be created that will periodically check if configFilename has been created or modified. The period is determined by the delay argument. If a change or file creation is detected, then configFilename is read to configure log4j.

 protected  void configureLoggerFactory(Properties props) 
{
    String factoryClassName = OptionConverter.findAndSubst(LOGGER_FACTORY_KEY,
							   props);
    if(factoryClassName != null) {
      LogLog.debug("Setting category factory to ["+factoryClassName+"].");
      loggerFactory = (LoggerFactory)
	          OptionConverter.instantiateByClassName(factoryClassName,
							 LoggerFactory.class,
							 loggerFactory);
      PropertySetter.setProperties(loggerFactory, props, FACTORY_PREFIX + ".");
    }
}

Check the provided Properties object for a LoggerFactory entry specified by #LOGGER_FACTORY_KEY . If such an entry exists, an attempt is made to create an instance using the default constructor. This instance is used for subsequent Category creations within this configurator.

  void configureRootCategory(Properties props,
    LoggerRepository hierarchy) 
{
    String effectiveFrefix = ROOT_LOGGER_PREFIX;
    String value = OptionConverter.findAndSubst(ROOT_LOGGER_PREFIX, props);
    if(value == null) {
      value = OptionConverter.findAndSubst(ROOT_CATEGORY_PREFIX, props);
      effectiveFrefix = ROOT_CATEGORY_PREFIX;
    }
    if(value == null)
      LogLog.debug("Could not find root logger information. Is this OK?");
    else {
      Logger root = hierarchy.getRootLogger();
      synchronized(root) {
	parseCategory(props, root, effectiveFrefix, INTERNAL_ROOT_NAME, value);
      }
    }
}

 public  void doConfigure(String configFileName,
    LoggerRepository hierarchy) 
{
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
    Properties props = new Properties();
    FileInputStream istream = null;
    try {
      istream = new FileInputStream(configFileName);
      props.load(istream);
      istream.close();
    }
    catch (Exception e) {
      LogLog.error("Could not read configuration file ["+configFileName+"].", e);
      LogLog.error("Ignoring configuration file [" + configFileName+"].");
      return;
    } finally {
        if(istream != null) {
            try {
                istream.close();
            } catch(Throwable ignore) {
            }
        }
    }
    // If we reach here, then the config file is alright.
    doConfigure(props, hierarchy);
}

Read configuration from a file. The existing configuration is not cleared nor reset. If you require a different behavior, then call resetConfiguration method before calling doConfigure.

The configuration file consists of statements in the format key=value. The syntax of different configuration elements are discussed below.

Repository-wide threshold

The repository-wide threshold filters logging requests by level regardless of logger. The syntax is:

log4j.threshold=[level]

The level value can consist of the string values OFF, FATAL, ERROR, WARN, INFO, DEBUG, ALL or a custom level value. A custom level value can be specified in the form level#classname. By default the repository-wide threshold is set to the lowest possible value, namely the level ALL.

Appender configuration

Appender configuration syntax is:

# For appender named appenderName, set its class.
# Note: The appender name can contain dots.
log4j.appender.appenderName=fully.qualified.name.of.appender.class

# Set appender specific options.
log4j.appender.appenderName.option1=value1
...
log4j.appender.appenderName.optionN=valueN

For each named appender you can configure its Layout . The syntax for configuring an appender's layout is:

log4j.appender.appenderName.layout=fully.qualified.name.of.layout.class
log4j.appender.appenderName.layout.option1=value1
....
log4j.appender.appenderName.layout.optionN=valueN

Configuring loggers

The syntax for configuring the root logger is:

log4j.rootLogger=[level], appenderName, appenderName, ...

This syntax means that an optional level can be supplied followed by appender names separated by commas.

The level value can consist of the string values OFF, FATAL, ERROR, WARN, INFO, DEBUG, ALL or a custom level value. A custom level value can be specified in the form level#classname.

If a level value is specified, then the root level is set to the corresponding level. If no level value is specified, then the root level remains untouched.

The root logger can be assigned multiple appenders.

Each appenderName (separated by commas) will be added to the root logger. The named appender is defined using the appender syntax defined above.

For non-root categories the syntax is almost the same:

log4j.logger.logger_name=[level|INHERITED|NULL], appenderName, appenderName, ...

The meaning of the optional level value is discussed above in relation to the root logger. In addition however, the value INHERITED can be specified meaning that the named logger should inherit its level from the logger hierarchy.

If no level value is supplied, then the level of the named logger remains untouched.

By default categories inherit their level from the hierarchy. However, if you set the level of a logger and later decide that that logger should inherit its level, then you should specify INHERITED as the value for the level value. NULL is a synonym for INHERITED.

Similar to the root logger syntax, each appenderName (separated by commas) will be attached to the named logger.

See the appender additivity rule in the user manual for the meaning of the additivity flag.

ObjectRenderers

You can customize the way message objects of a given type are converted to String before being logged. This is done by specifying an ObjectRenderer for the object type would like to customize.

The syntax is:

log4j.renderer.fully.qualified.name.of.rendered.class=fully.qualified.name.of.rendering.class

As in,

log4j.renderer.my.Fruit=my.FruitRenderer

Logger Factories

The usage of custom logger factories is discouraged and no longer documented.

Resetting Hierarchy

The hierarchy will be reset before configuration when log4j.reset=true is present in the properties file.

Example

An example configuration is given below. Other configuration file examples are given in the examples folder.

# Set options for appender named "A1".
# Appender "A1" will be a SyslogAppender
log4j.appender.A1=org.apache.log4j.net.SyslogAppender

# The syslog daemon resides on www.abc.net
log4j.appender.A1.SyslogHost=www.abc.net

# A1's layout is a PatternLayout, using the conversion pattern
# %r %-5p %c{2} %M.%L %x - %m\n. Thus, the log output will
# include # the relative time since the start of the application in
# milliseconds, followed by the level of the log request,
# followed by the two rightmost components of the logger name,
# followed by the callers method name, followed by the line number,
# the nested disgnostic context and finally the message itself.
# Refer to the documentation of PatternLayout  for further information
# on the syntax of the ConversionPattern key.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-4r %-5p %c{2} %M.%L %x - %m\n

# Set options for appender named "A2"
# A2 should be a RollingFileAppender, with maximum file size of 10 MB
# using at most one backup file. A2's layout is TTCC, using the
# ISO8061 date format with context printing enabled.
log4j.appender.A2=org.apache.log4j.RollingFileAppender
log4j.appender.A2.MaxFileSize=10MB
log4j.appender.A2.MaxBackupIndex=1
log4j.appender.A2.layout=org.apache.log4j.TTCCLayout
log4j.appender.A2.layout.ContextPrinting=enabled
log4j.appender.A2.layout.DateFormat=ISO8601

# Root logger set to DEBUG using the A2 appender defined above.
log4j.rootLogger=DEBUG, A2

# Logger definitions:
# The SECURITY logger inherits is level from root. However, it's output
# will go to A1 appender defined above. It's additivity is non-cumulative.
log4j.logger.SECURITY=INHERIT, A1
log4j.additivity.SECURITY=false

# Only warnings or above will be logged for the logger "SECURITY.access".
# Output will go to A1.
log4j.logger.SECURITY.access=WARN


# The logger "class.of.the.day" inherits its level from the
# logger hierarchy. Output will go to the appender's of the root
# logger, A2 in this case.
log4j.logger.class.of.the.day=INHERIT

Refer to the setOption method in each Appender and Layout for class specific options.

Use the # or ! characters at the beginning of a line for comments.

 public  void doConfigure(Properties properties,
    LoggerRepository hierarchy) 
{
    String value = properties.getProperty(LogLog.DEBUG_KEY);
    if(value == null) {
      value = properties.getProperty("log4j.configDebug");
      if(value != null)
	LogLog.warn("[log4j.configDebug] is deprecated. Use [log4j.debug] instead.");
    }
    if(value != null) {
      LogLog.setInternalDebugging(OptionConverter.toBoolean(value, true));
    }
      //
      //   if log4j.reset=true then
      //        reset hierarchy
    String reset = properties.getProperty(RESET_KEY);
    if (reset != null && OptionConverter.toBoolean(reset, false)) {
          hierarchy.resetConfiguration();
    }
    String thresholdStr = OptionConverter.findAndSubst(THRESHOLD_PREFIX,
						       properties);
    if(thresholdStr != null) {
      hierarchy.setThreshold(OptionConverter.toLevel(thresholdStr,
						     (Level) Level.ALL));
      LogLog.debug("Hierarchy threshold set to ["+hierarchy.getThreshold()+"].");
    }
    configureRootCategory(properties, hierarchy);
    configureLoggerFactory(properties);
    parseCatsAndRenderers(properties, hierarchy);
    LogLog.debug("Finished configuring.");
    // We don't want to hold references to appenders preventing their
    // garbage collection.
    registry.clear();
}

Read configuration options from properties. See #doConfigure(String, LoggerRepository) for the expected format.

 public  void doConfigure(URL configURL,
    LoggerRepository hierarchy) 
{
    Properties props = new Properties();
    LogLog.debug("Reading configuration from URL " + configURL);
    InputStream istream = null;
    try {
      istream = configURL.openStream();
      props.load(istream);
    }
    catch (Exception e) {
      LogLog.error("Could not read configuration file from URL [" + configURL
		   + "].", e);
      LogLog.error("Ignoring configuration file [" + configURL +"].");
      return;
    }
    finally {
        if (istream != null) {
            try {
                istream.close();
            } catch(Exception ignore) {
            }
        }
    }
    doConfigure(props, hierarchy);
}

Read configuration options from url configURL.

  void parseAdditivityForLogger(Properties props,
    Logger cat,
    String loggerName) 
{
    String value = OptionConverter.findAndSubst(ADDITIVITY_PREFIX + loggerName,
					     props);
    LogLog.debug("Handling "+ADDITIVITY_PREFIX + loggerName+"=["+value+"]");
    // touch additivity only if necessary
    if((value != null) && (!value.equals(""))) {
      boolean additivity = OptionConverter.toBoolean(value, true);
      LogLog.debug("Setting additivity for \""+loggerName+"\" to "+
		   additivity);
      cat.setAdditivity(additivity);
    }
}

Parse the additivity option for a non-root category.

 Appender parseAppender(Properties props,
    String appenderName) 
{
    Appender appender = registryGet(appenderName);
    if((appender != null)) {
      LogLog.debug("Appender \"" + appenderName + "\" was already parsed.");
      return appender;
    }
    // Appender was not previously initialized.
    String prefix = APPENDER_PREFIX + appenderName;
    String layoutPrefix = prefix + ".layout";
    appender = (Appender) OptionConverter.instantiateByKey(props, prefix,
					      org.apache.log4j.Appender.class,
					      null);
    if(appender == null) {
      LogLog.error(
              "Could not instantiate appender named \"" + appenderName+"\".");
      return null;
    }
    appender.setName(appenderName);
    if(appender instanceof OptionHandler) {
      if(appender.requiresLayout()) {
	Layout layout = (Layout) OptionConverter.instantiateByKey(props,
								  layoutPrefix,
								  Layout.class,
								  null);
	if(layout != null) {
	  appender.setLayout(layout);
	  LogLog.debug("Parsing layout options for \"" + appenderName +"\".");
	  //configureOptionHandler(layout, layoutPrefix + ".", props);
          PropertySetter.setProperties(layout, props, layoutPrefix + ".");
	  LogLog.debug("End of parsing for \"" + appenderName +"\".");
	}
      }
      //configureOptionHandler((OptionHandler) appender, prefix + ".", props);
      PropertySetter.setProperties(appender, props, prefix + ".");
      LogLog.debug("Parsed \"" + appenderName +"\" options.");
    }
    registryPut(appender);
    return appender;
}

  void parseCategory(Properties props,
    Logger logger,
    String optionKey,
    String loggerName,
    String value) 
{
    LogLog.debug("Parsing for [" +loggerName +"] with value=[" + value+"].");
    // We must skip over ',' but not white space
    StringTokenizer st = new StringTokenizer(value, ",");
    // If value is not in the form ", appender.." or "", then we should set
    // the level of the loggeregory.
    if(!(value.startsWith(",") || value.equals(""))) {
      // just to be on the safe side...
      if(!st.hasMoreTokens())
	return;
      String levelStr = st.nextToken();
      LogLog.debug("Level token is [" + levelStr + "].");
      // If the level value is inherited, set category level value to
      // null. We also check that the user has not specified inherited for the
      // root category.
      if(INHERITED.equalsIgnoreCase(levelStr) || 
 	                                  NULL.equalsIgnoreCase(levelStr)) {
	if(loggerName.equals(INTERNAL_ROOT_NAME)) {
	  LogLog.warn("The root logger cannot be set to null.");
	} else {
	  logger.setLevel(null);
	}
      } else {
	logger.setLevel(OptionConverter.toLevel(levelStr, (Level) Level.DEBUG));
      }
      LogLog.debug("Category " + loggerName + " set to " + logger.getLevel());
    }
    // Begin by removing all existing appenders.
    logger.removeAllAppenders();
    Appender appender;
    String appenderName;
    while(st.hasMoreTokens()) {
      appenderName = st.nextToken().trim();
      if(appenderName == null || appenderName.equals(","))
	continue;
      LogLog.debug("Parsing appender named \"" + appenderName +"\".");
      appender = parseAppender(props, appenderName);
      if(appender != null) {
	logger.addAppender(appender);
      }
    }
}

This method must work for the root category as well.

 protected  void parseCatsAndRenderers(Properties props,
    LoggerRepository hierarchy) 
{
    Enumeration enumeration = props.propertyNames();
    while(enumeration.hasMoreElements()) {
      String key = (String) enumeration.nextElement();
      if(key.startsWith(CATEGORY_PREFIX) || key.startsWith(LOGGER_PREFIX)) {
	String loggerName = null;
	if(key.startsWith(CATEGORY_PREFIX)) {
	  loggerName = key.substring(CATEGORY_PREFIX.length());
	} else if(key.startsWith(LOGGER_PREFIX)) {
	  loggerName = key.substring(LOGGER_PREFIX.length());
	}
	String value =  OptionConverter.findAndSubst(key, props);
	Logger logger = hierarchy.getLogger(loggerName, loggerFactory);
	synchronized(logger) {
	  parseCategory(props, logger, key, loggerName, value);
	  parseAdditivityForLogger(props, logger, loggerName);
	}
      } else if(key.startsWith(RENDERER_PREFIX)) {
	String renderedClass = key.substring(RENDERER_PREFIX.length());
	String renderingClass = OptionConverter.findAndSubst(key, props);
	if(hierarchy instanceof RendererSupport) {
	  RendererMap.addRenderer((RendererSupport) hierarchy, renderedClass,
				  renderingClass);
	}
      }
    }
}

Parse non-root elements, such non-root categories and renderers.

 Appender registryGet(String name) 
{
    return (Appender) registry.get(name);
}

  void registryPut(Appender appender) 
{
    registry.put(appender.getName(), appender);
}