org.apache.logging.log4j.core.lookup
Class MapLookup

java.lang.Object
  extended by org.apache.logging.log4j.core.lookup.MapLookup
All Implemented Interfaces:
StrLookup

@Plugin(name="map",
        category="Lookup")
public class MapLookup
extends Object
implements StrLookup

The basis for a lookup based on a Map.


Constructor Summary
MapLookup()
          Constructor when used directly as a plugin.
MapLookup(Map<String,String> map)
          Creates a new instance backed by a Map.
 
Method Summary
 String lookup(LogEvent event, String key)
          Looks up a String key to a String value possibly using the current LogEvent.
 String lookup(String key)
          Looks up a String key to a String value using the map.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MapLookup

public MapLookup(Map<String,String> map)
Creates a new instance backed by a Map. Used by the default lookup.

Parameters:
map - the map of keys to values, may be null

MapLookup

public MapLookup()
Constructor when used directly as a plugin.

Method Detail

lookup

public String lookup(String key)
Looks up a String key to a String value using the map.

If the map is null, then null is returned. The map result object is converted to a string using toString().

Specified by:
lookup in interface StrLookup
Parameters:
key - the key to be looked up, may be null
Returns:
the matching value, null if no match

lookup

public String lookup(LogEvent event,
                     String key)
Description copied from interface: StrLookup
Looks up a String key to a String value possibly using the current LogEvent.

The internal implementation may use any mechanism to return the value. The simplest implementation is to use a Map. However, virtually any implementation is possible.

For example, it would be possible to implement a lookup that used the key as a primary key, and looked up the value on demand from the database Or, a numeric based implementation could be created that treats the key as an integer, increments the value and return the result as a string - converting 1 to 2, 15 to 16 etc.

The StrLookup.lookup(String) method always returns a String, regardless of the underlying data, by converting it as necessary. For example:

 Map map = new HashMap();
 map.put("number", new Integer(2));
 assertEquals("2", StrLookup.mapLookup(map).lookup("number"));
 

Specified by:
lookup in interface StrLookup
Parameters:
event - The current LogEvent.
key - the key to be looked up, may be null
Returns:
the matching value, null if no match


Copyright © 1999-2014 Apache Software Foundation. All Rights Reserved.
Apache Logging, Apache Log4j, Log4j, Apache, the Apache feather logo, the Apache Logging project logo, and the Apache Log4j logo are trademarks of The Apache Software Foundation.