Package org.apache.log4j

Class Category

  • All Implemented Interfaces:
    AppenderAttachable
    Direct Known Subclasses:
    Logger
    public class Category
extends java.lang.Object
implements AppenderAttachable
    This class has been deprecated and replaced by the Logger subclass. It will be kept around to preserve backward compatibility until mid 2003.

    Logger is a subclass of Category, i.e. it extends Category. In other words, a logger is a category. Thus, all operations that can be performed on a category can be performed on a logger. Internally, whenever log4j is asked to produce a Category object, it will instead produce a Logger object. Log4j 1.2 will never produce Category objects but only Logger instances. In order to preserve backward compatibility, methods that previously accepted category objects still continue to accept category objects.

    For example, the following are all legal and will work as expected. 

           // Deprecated form:
       Category cat = Category.getInstance("foo.bar")
   
       // Preferred form for retrieving loggers:
       Logger logger = Logger.getLogger("foo.bar")

    The first form is deprecated and should be avoided.

    There is absolutely no need for new client code to use or refer to the Category class. Whenever possible, please avoid referring to it or using it.

    See the short manual for an introduction on this class.

    See the document entitled preparing for log4j 1.3 for a more detailed discussion.

    Author:
    Ceki Gülcü, Anders Kristensen

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected boolean additive
      Additivity is set to true by default, that is children inherit the appenders of their ancestors by default.
      protected Level level
      The assigned level of this category.
      protected java.lang.String name
      The name of this category.
      protected Category parent
      The parent of this category.
      protected LoggerRepository repository  
      protected java.util.ResourceBundle resourceBundle  

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected Category​(java.lang.String name)
      This constructor created a new Category instance and sets its name.

    • Field Detail

      • name

        protected java.lang.String name
        The name of this category.

      • level

        protected volatile Level level
        The assigned level of this category. The level variable need not be assigned a value in which case it is inherited form the hierarchy.

      • parent

        protected volatile Category parent
        The parent of this category. All categories have at least one ancestor which is the root category.

      • resourceBundle

        protected java.util.ResourceBundle resourceBundle

      • additive

        protected boolean additive
        Additivity is set to true by default, that is children inherit the appenders of their ancestors by default. If this variable is set to false then the appenders found in the ancestors of this category are not used. However, the children of this category will inherit its appenders, unless the children have their additivity flag set to false too. See the user manual for more details.

    • Constructor Detail

      • Category

        protected Category​(java.lang.String name)
        This constructor created a new Category instance and sets its name.

        It is intended to be used by sub-classes only. You should not create categories directly.

        Parameters:
        name - The name of the category.

    • Method Detail

      • addAppender

        public void addAppender​(Appender newAppender)
        Add newAppender to the list of appenders of this Category instance.

        If newAppender is already in the list of appenders, then it won't be added again.

        Specified by:
        addAppender in interface AppenderAttachable

      • assertLog

        public void assertLog​(boolean assertion,
                      java.lang.String msg)
        If assertion parameter is false, then logs msg as an error statement.

        The assert method has been renamed to assertLog because assert is a language reserved word in JDK 1.4.

        Parameters:
        assertion -
        msg - The message to print if assertion is false.
        Since:
        1.2

      • callAppenders

        public void callAppenders​(LoggingEvent event)
        Call the appenders in the hierrachy starting at this. If no appenders could be found, emit a warning.

        This method calls all the appenders inherited from the hierarchy circumventing any evaluation of whether to log or not to log the particular log request.

        Parameters:
        event - the event to log.

      • debug

        public void debug​(java.lang.Object message)
        Log a message object with the DEBUG level.

        This method first checks if this category is DEBUG enabled by comparing the level of this category with the DEBUG level. If this category is DEBUG enabled, then it converts the message object (passed as parameter) to a string by invoking the appropriate ObjectRenderer. It then proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

        WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the debug(Object, Throwable) form instead.

        Parameters:
        message - the message object to log.

      • debug

        public void debug​(java.lang.Object message,
                  java.lang.Throwable t)
        Log a message object with the DEBUG level including the stack trace of the Throwable t passed as parameter.

        See debug(Object) form for more detailed information.

        Parameters:
        message - the message object to log.
        t - the exception to log, including its stack trace.

      • error

        public void error​(java.lang.Object message)
        Log a message object with the ERROR Level.

        This method first checks if this category is ERROR enabled by comparing the level of this category with ERROR Level. If this category is ERROR enabled, then it converts the message object passed as parameter to a string by invoking the appropriate ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

        WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the error(Object, Throwable) form instead.

        Parameters:
        message - the message object to log

      • error

        public void error​(java.lang.Object message,
                  java.lang.Throwable t)
        Log a message object with the ERROR level including the stack trace of the Throwable t passed as parameter.

        See error(Object) form for more detailed information.

        Parameters:
        message - the message object to log.
        t - the exception to log, including its stack trace.

      • exists

        public static Logger exists​(java.lang.String name)
        Deprecated.
        Please use LogManager.exists(java.lang.String) instead.
        If the named category exists (in the default hierarchy) then it returns a reference to the category, otherwise it returns null.
        Since:
        0.8.5

      • fatal

        public void fatal​(java.lang.Object message)
        Log a message object with the FATAL Level.

        This method first checks if this category is FATAL enabled by comparing the level of this category with FATAL Level. If the category is FATAL enabled, then it converts the message object passed as parameter to a string by invoking the appropriate ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

        WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the fatal(Object, Throwable) form instead.

        Parameters:
        message - the message object to log

      • fatal

        public void fatal​(java.lang.Object message,
                  java.lang.Throwable t)
        Log a message object with the FATAL level including the stack trace of the Throwable t passed as parameter.

        See fatal(Object) for more detailed information.

        Parameters:
        message - the message object to log.
        t - the exception to log, including its stack trace.

      • forcedLog

        protected void forcedLog​(java.lang.String fqcn,
                         Priority level,
                         java.lang.Object message,
                         java.lang.Throwable t)
        This method creates a new logging event and logs the event without further checks.

      • getAdditivity

        public boolean getAdditivity()
        Get the additivity flag for this Category instance.

      • getAllAppenders

        public java.util.Enumeration getAllAppenders()
        Get the appenders contained in this category as an Enumeration. If no appenders can be found, then a NullEnumeration is returned.
        Specified by:
        getAllAppenders in interface AppenderAttachable
        Returns:
        Enumeration An enumeration of the appenders in this category.

      • getAppender

        public Appender getAppender​(java.lang.String name)
        Look for the appender named as name.

        Return the appender with that name if in the list. Return null otherwise.

        Specified by:
        getAppender in interface AppenderAttachable

      • getEffectiveLevel

        public Level getEffectiveLevel()
        Starting from this category, search the category hierarchy for a non-null level and return it. Otherwise, return the level of the root category.

        The Category class is designed so that this method executes as quickly as possible.

      • getCurrentCategories

        public static java.util.Enumeration getCurrentCategories()
        Deprecated.
        Please use LogManager.getCurrentLoggers() instead.
        Returns all the currently defined categories in the default hierarchy as an Enumeration.

        The root category is not included in the returned Enumeration.

      • getName

        public final java.lang.String getName()
        Return the category name.

      • getParent

        public final Category getParent()
        Returns the parent of this category. Note that the parent of a given category may change during the lifetime of the category.

        The root category will return null.

        Since:
        1.2

      • getLevel

        public final Level getLevel()
        Returns the assigned Level, if any, for this Category.
        Returns:
        Level - the assigned Level, can be null.

      • getPriority

        public final Level getPriority()
        Deprecated.
        Please use getLevel() instead.

      • getResourceBundle

        public java.util.ResourceBundle getResourceBundle()
        Return the inherited ResourceBundle for this category.

        This method walks the hierarchy to find the appropriate resource bundle. It will return the resource bundle attached to the closest ancestor of this category, much like the way priorities are searched. In case there is no bundle in the hierarchy then null is returned.

        Since:
        0.9.0

      • getResourceBundleString

        protected java.lang.String getResourceBundleString​(java.lang.String key)
        Returns the string resource coresponding to key in this category's inherited resource bundle. See also getResourceBundle().

        If the resource cannot be found, then an error message will be logged complaining about the missing resource.

      • info

        public void info​(java.lang.Object message)
        Log a message object with the INFO Level.

        This method first checks if this category is INFO enabled by comparing the level of this category with INFO Level. If the category is INFO enabled, then it converts the message object passed as parameter to a string by invoking the appropriate ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hierarchy depending on the value of the additivity flag.

        WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the info(Object, Throwable) form instead.

        Parameters:
        message - the message object to log

      • info

        public void info​(java.lang.Object message,
                 java.lang.Throwable t)
        Log a message object with the INFO level including the stack trace of the Throwable t passed as parameter.

        See info(Object) for more detailed information.

        Parameters:
        message - the message object to log.
        t - the exception to log, including its stack trace.

      • isAttached

        public boolean isAttached​(Appender appender)
        Is the appender passed as parameter attached to this category?
        Specified by:
        isAttached in interface AppenderAttachable

      • isDebugEnabled

        public boolean isDebugEnabled()
        Check whether this category is enabled for the DEBUG Level.

        This function is intended to lessen the computational cost of disabled log debug statements.

        For some cat Category object, when you write, 

              cat.debug("This is entry number: " + i );

        You incur the cost constructing the message, concatenatiion in this case, regardless of whether the message is logged or not.

        If you are worried about speed, then you should write 

                 if(cat.isDebugEnabled()) {
           cat.debug("This is entry number: " + i );
         }

        This way you will not incur the cost of parameter construction if debugging is disabled for cat. On the other hand, if the cat is debug enabled, you will incur the cost of evaluating whether the category is debug enabled twice. Once in isDebugEnabled and once in the debug. This is an insignificant overhead since evaluating a category takes about 1%% of the time it takes to actually log.

        Returns:
        boolean - true if this category is debug enabled, false otherwise.

      • isEnabledFor

        public boolean isEnabledFor​(Priority level)
        Check whether this category is enabled for a given Level passed as parameter. See also isDebugEnabled().
        Returns:
        boolean True if this category is enabled for level.

      • isInfoEnabled

        public boolean isInfoEnabled()
        Check whether this category is enabled for the info Level. See also isDebugEnabled().
        Returns:
        boolean - true if this category is enabled for level info, false otherwise.

      • l7dlog

        public void l7dlog​(Priority priority,
                   java.lang.String key,
                   java.lang.Throwable t)
        Log a localized message. The user supplied parameter key is replaced by its localized version from the resource bundle.
        Since:
        0.8.4
        See Also:
        setResourceBundle(java.util.ResourceBundle)

      • l7dlog

        public void l7dlog​(Priority priority,
                   java.lang.String key,
                   java.lang.Object[] params,
                   java.lang.Throwable t)
        Log a localized and parameterized message. First, the user supplied key is searched in the resource bundle. Next, the resulting pattern is formatted using MessageFormat.format(String,Object[]) method with the user supplied object array params.
        Since:
        0.8.4

      • log

        public void log​(Priority priority,
                java.lang.Object message,
                java.lang.Throwable t)
        This generic form is intended to be used by wrappers.

      • log

        public void log​(Priority priority,
                java.lang.Object message)
        This generic form is intended to be used by wrappers.

      • log

        public void log​(java.lang.String callerFQCN,
                Priority level,
                java.lang.Object message,
                java.lang.Throwable t)
        This is the most generic printing method. It is intended to be invoked by wrapper classes.
        Parameters:
        callerFQCN - The wrapper class' fully qualified class name.
        level - The level of the logging request.
        message - The message of the logging request.
        t - The throwable of the logging request, may be null.

      • removeAllAppenders

        public void removeAllAppenders()
        Remove all previously added appenders from this Category instance.

        This is useful when re-reading configuration information.

        Specified by:
        removeAllAppenders in interface AppenderAttachable

      • removeAppender

        public void removeAppender​(Appender appender)
        Remove the appender passed as parameter form the list of appenders.
        Specified by:
        removeAppender in interface AppenderAttachable
        Since:
        0.8.2

      • removeAppender

        public void removeAppender​(java.lang.String name)
        Remove the appender with the name passed as parameter form the list of appenders.
        Specified by:
        removeAppender in interface AppenderAttachable
        Since:
        0.8.2

      • setAdditivity

        public void setAdditivity​(boolean additive)
        Set the additivity flag for this Category instance.
        Since:
        0.8.1

      • setLevel

        public void setLevel​(Level level)
        Set the level of this Category. If you are passing any of Level.DEBUG, Level.INFO, Level.WARN, Level.ERROR, Level.FATAL as a parameter, you need to case them as Level.

        As in 

            logger.setLevel((Level) Level.DEBUG);

        Null values are admitted.

      • shutdown

        public static void shutdown()
        Deprecated.
        Please use LogManager.shutdown() instead.
        Calling this method will safely close and remove all appenders in all the categories including root contained in the default hierachy.

        Some appenders such as SocketAppender and AsyncAppender need to be closed before the application exists. Otherwise, pending logging events might be lost.

        The shutdown method is careful to close nested appenders before closing regular appenders. This is allows configurations where a regular appender is attached to a category and again to a nested appender.

        Since:
        1.0

      • warn

        public void warn​(java.lang.Object message)
        Log a message object with the WARN Level.

        This method first checks if this category is WARN enabled by comparing the level of this category with WARN Level. If the category is WARN enabled, then it converts the message object passed as parameter to a string by invoking the appropriate ObjectRenderer. It proceeds to call all the registered appenders in this category and also higher in the hieararchy depending on the value of the additivity flag.

        WARNING Note that passing a Throwable to this method will print the name of the Throwable but no stack trace. To print a stack trace use the warn(Object, Throwable) form instead.

        Parameters:
        message - the message object to log.

      • warn

        public void warn​(java.lang.Object message,
                 java.lang.Throwable t)
        Log a message with the WARN level including the stack trace of the Throwable t passed as parameter.

        See warn(Object) for more detailed information.

        Parameters:
        message - the message object to log.
        t - the exception to log, including its stack trace.