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

java.lang.Object
  org.apache.logging.log4j.core.lookup.MapLookup

All Implemented Interfaces:

StrLookup

Direct Known Subclasses:

JmxRuntimeInputArgumentsLookup

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

A map-based lookup.

Field Summary

Fields inherited from interface org.apache.logging.log4j.core.lookup.StrLookup

CATEGORY

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.
static void	setMainArguments(String[] args) An application's public static main(String[]) method calls this method to make its main arguments available for lookup with the prefix main.

Methods inherited from class java.lang.Object

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

Constructor Detail

MapLookup

public MapLookup()

Constructor when used directly as a plugin.

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

Method Detail

setMainArguments

public static void setMainArguments(String[] args)

An application's public static main(String[]) method calls this method to make its main arguments available for lookup with the prefix main.

The map provides two kinds of access: First by index, starting at "0", "1" and so on. For example, the command line --file path/file.txt -x 2 can be accessed from a configuration file with:

• "main:0" = "--file"
• "main:1" = "path/file.txt"
• "main:2" = "-x"
• "main:3" = "2"

Second using the argument at position n as the key to access the value at n+1.

• "main:--file" = "path/file.txt"
• "main:-x" = "2"

Parameters:

args - An application's public static main(String[]) arguments.

Since:

2.1

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.

This method always returns a String, regardless of the underlying data, by converting it as necessary. For example:

 Map<String, Object> map = new HashMap<String, Object>();
 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

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