Package org.apache.logging.log4j.util

Class Constants

  • public final class Constants
extends java.lang.Object
    Log4j API Constants.
    Since:
    2.6.2

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static byte[] EMPTY_BYTE_ARRAY
      The empty array.
      static java.lang.Object[] EMPTY_OBJECT_ARRAY
      The empty array.
      static boolean ENABLE_THREADLOCALS
      Specifies whether Log4j can bind non-JRE types to ThreadLocals
      static boolean IS_WEB_APP
      Specifies whether Log4j is used in a servlet container
      static int JAVA_MAJOR_VERSION
      Java major version.
      static java.lang.String LOG4J2_DEBUG
      Name of the system property that will turn on TRACE level internal log4j2 status logging.
      static int MAX_REUSABLE_MESSAGE_SIZE
      Maximum size of the StringBuilders used in RingBuffer LogEvents to store the contents of reusable Messages.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private Constants()
      Prevent class instantiation.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      private static int getMajorVersion()  
      (package private) static int getMajorVersion​(java.lang.String version)  
      private static boolean isClassAvailable​(java.lang.String className)
      Determines if a named Class can be loaded or not.
      private static int size​(java.lang.String property, int defaultValue)  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • IS_WEB_APP

        public static final boolean IS_WEB_APP
        Specifies whether Log4j is used in a servlet container

        If true Log4j disables the features, which are incompatible with a typical servlet application:

        1. It disables the usage of ThreadLocals for object pooling (unless the user has explicitly provided a ENABLE_THREADLOCALS property)
        2. It uses a web-application safe implementation of ThreadContextMap (see Provider.getThreadContextMap()),
        3. It disables the shutdown hook,
        4. It uses the caller thread to send JMX notifications.

        The value of this constant depends upon the presence of the Servlet API on the classpath and can be overridden using the "log4j2.isWebapp" system property.

      • ENABLE_THREADLOCALS

        public static final boolean ENABLE_THREADLOCALS
        Specifies whether Log4j can bind non-JRE types to ThreadLocals

        The value of this constant is true, unless Log4j is running in a servlet container (cf. IS_WEB_APP). Use the "log4j2.enableThreadlocals system property to override its value.

        In order to enable the garbage-free behavior described in LOG4J2-1270, this constant must be true.

        Warning: This setting does not disable all thread locals. It only disables those thread locals that can cause a classloader memory leak.

      • JAVA_MAJOR_VERSION

        public static final int JAVA_MAJOR_VERSION
        Java major version.
        Since:
        2.8.1

      • MAX_REUSABLE_MESSAGE_SIZE

        public static final int MAX_REUSABLE_MESSAGE_SIZE
        Maximum size of the StringBuilders used in RingBuffer LogEvents to store the contents of reusable Messages. After a large message has been delivered to the appenders, the StringBuilder is trimmed to this size.

        The default value is 518, which allows the StringBuilder to resize three times from its initial size. Users can override with system property "log4j.maxReusableMsgSize".

        Since:
        2.9.0

      • LOG4J2_DEBUG

        public static final java.lang.String LOG4J2_DEBUG
        Name of the system property that will turn on TRACE level internal log4j2 status logging.

        If system property "log4j2.debug" is either defined empty or its value equals to true (ignoring case), all internal log4j2 logging will be printed to the console. The presence of this system property overrides any value set in the configuration's <Configuration status="<level>" ...> status attribute, as well as any value set for system property org.apache.logging.log4j.simplelog.StatusLogger.level.

        Since:
        2.9.0
        See Also:
        Constant Field Values

      • EMPTY_OBJECT_ARRAY

        public static final java.lang.Object[] EMPTY_OBJECT_ARRAY
        The empty array.
        Since:
        2.15.0

      • EMPTY_BYTE_ARRAY

        public static final byte[] EMPTY_BYTE_ARRAY
        The empty array.
        Since:
        2.15.0

    • Constructor Detail

      • Constants

        private Constants()
        Prevent class instantiation.

    • Method Detail

      • size

        private static int size​(java.lang.String property,
                        int defaultValue)

      • isClassAvailable

        private static boolean isClassAvailable​(java.lang.String className)
        Determines if a named Class can be loaded or not.
        Parameters:
        className - The class name.
        Returns:
        true if the class could be found or false otherwise.

      • getMajorVersion

        private static int getMajorVersion()

      • getMajorVersion

        static int getMajorVersion​(java.lang.String version)