Package org.apache.logging.log4j.core.lookup

Class MainMapLookup

    • Field Summary

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

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.String lookup​(java.lang.String key)
      Looks up a String key to a String value using the map.
      java.lang.String lookup​(LogEvent event, java.lang.String key)
      Looks up a String key to a String value possibly using the current LogEvent.
      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 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"

        Note: Many applications use leading dashes to identify command arguments. Specifying "main:--file would result in the lookup failing because it would look for a variable named "main" with a default value of "-file". To avoid this the ":" separating the Lookup name from the key must be followed by a backslash as an escape character.

        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