org.apache.logging.log4j.core.lookup

Class MainMapLookup

java.lang.Object

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

org.apache.logging.log4j.core.lookup.MainMapLookup

All Implemented Interfaces:

StrLookup

@Plugin(name="main",
        category="Lookup")
public class MainMapLookup
extends MapLookup

A map-based lookup for main arguments. See setMainArguments(String[]).

Since:

2.4

Field Summary

Fields

Modifier and Type	Field and Description
(package private) static MapLookup	MAIN_SINGLETON A singleton used by a main method to save its arguments.

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

CATEGORY

Constructor Summary

Constructors

Constructor and Description
MainMapLookup() Constructor when used directly as a plugin.
MainMapLookup(java.util.Map<java.lang.String,java.lang.String> map)

Method Summary

Modifier and Type	Method and Description
java.lang.String	lookup(LogEvent event, java.lang.String key) Looks up a String key to a String value possibly using the current LogEvent.
java.lang.String	lookup(java.lang.String key) Looks up a String key to a String value using the map.
static void	setMainArguments(java.lang.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 org.apache.logging.log4j.core.lookup.MapLookup

getMap, initMap, newMap, toMap, toMap

Methods inherited from class java.lang.Object

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

Field Detail

MAIN_SINGLETON

static final MapLookup MAIN_SINGLETON

A singleton used by a main method to save its arguments.

Constructor Detail

MainMapLookup

public MainMapLookup()

Constructor when used directly as a plugin.

MainMapLookup

public MainMapLookup(java.util.Map<java.lang.String,java.lang.String> map)

Method Detail

setMainArguments

public static void setMainArguments(java.lang.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.

lookup

public java.lang.String lookup(LogEvent event,
                               java.lang.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

Overrides:

lookup in class MapLookup

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 java.lang.String lookup(java.lang.String key)

Description copied from class: MapLookup

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

Overrides:

lookup in class MapLookup

Parameters:

key - the key to be looked up, may be null

Returns:

the matching value, null if no match