Class MDC


  • public class MDC
    extends java.lang.Object
    The MDC class is similar to the NDC class except that it is based on a map instead of a stack. It provides mapped diagnostic contexts. A Mapped Diagnostic Context, or MDC in short, is an instrument for distinguishing interleaved log output from different sources. Log output is typically interleaved when a server handles multiple clients near-simultaneously.

    The MDC is managed on a per thread basis. A child thread automatically inherits a copy of the mapped diagnostic context of its parent.

    The MDC class requires JDK 1.2 or above. Under JDK 1.1 the MDC will always return empty values but otherwise will not affect or harm your application.

    Since:
    1.2
    • Field Summary

      Fields 
      Modifier and Type Field Description
      (package private) static int HT_SIZE  
      (package private) boolean java1  
      (package private) static MDC mdc  
      private java.lang.reflect.Method removeMethod  
      (package private) java.lang.Object tlm  
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private MDC()  
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static void clear()
      Remove all values from the MDC.
      private void clear0()  
      static java.lang.Object get​(java.lang.String key)
      Get the context identified by the key parameter.
      private java.lang.Object get0​(java.lang.String key)  
      static java.util.Hashtable getContext()
      Get the current thread's MDC as a hashtable.
      private java.util.Hashtable getContext0()  
      static void put​(java.lang.String key, java.lang.Object o)
      Put a context value (the o parameter) as identified with the key parameter into the current thread's context map.
      private void put0​(java.lang.String key, java.lang.Object o)  
      static void remove​(java.lang.String key)
      Remove the the context identified by the key parameter.
      private void remove0​(java.lang.String key)  
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • mdc

        static final MDC mdc
      • java1

        boolean java1
      • tlm

        java.lang.Object tlm
      • removeMethod

        private java.lang.reflect.Method removeMethod
    • Constructor Detail

      • MDC

        private MDC()
    • Method Detail

      • put

        public static void put​(java.lang.String key,
                               java.lang.Object o)
        Put a context value (the o parameter) as identified with the key parameter into the current thread's context map.

        If the current thread does not have a context map it is created as a side effect.

      • get

        public static java.lang.Object get​(java.lang.String key)
        Get the context identified by the key parameter.

        This method has no side effects.

      • remove

        public static void remove​(java.lang.String key)
        Remove the the context identified by the key parameter.
      • getContext

        public static java.util.Hashtable getContext()
        Get the current thread's MDC as a hashtable. This method is intended to be used internally.
      • clear

        public static void clear()
        Remove all values from the MDC.
        Since:
        1.2.16
      • put0

        private void put0​(java.lang.String key,
                          java.lang.Object o)
      • get0

        private java.lang.Object get0​(java.lang.String key)
      • remove0

        private void remove0​(java.lang.String key)
      • getContext0

        private java.util.Hashtable getContext0()
      • clear0

        private void clear0()