MDC

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org.apache.log4j
Class MDC

java.lang.Object
  org.apache.log4j.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

(package private) static int HT_SIZE


(package private) boolean java1


(package private) static MDC mdc


(package private) java.lang.Object tlm


Constructor Summary

private MDC()


Method Summary

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

HT_SIZE

static final int HT_SIZE

See Also:: Constant Field Values

java1

boolean java1

tlm

java.lang.Object tlm

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.

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()