From :http://topic.csdn.net/t/20040706/20/3151154.html
!-----------------------------------------------------------------------------!   
  !                                                     PATTERN   FORMATS   GLOSSARY                                                       !   
  !-----------------------------------------------------------------------------!   
  !   %n   -   newline                                                                                                                                 !   
  !   %m   -   your   log   message                                                                                                               !   
  !   %p   -   message   priority   (FATAL,   ERROR,   WARN,   INFO,   DEBUG   or   custom)                       !   
  !   %r   -   millisecs   since   program   started   running                                                                 !   
  !    %%  -   percent   sign   in   output                                                                                                   !   
  !                                                                                                                                                           !   
  !-----------------------SOME   MORE   CLUTTER   IN   YOUR   LOG-------------------------!   
  !   %c   -   name   of   your   category   (logger),   %c{2}   will   outputs   last   two   components   !   
  !   %t   -   name   of   current   thread                                                                                                   !   
  !   %x   -   Nested   Diagnostic   Context   (NDC)   (you   supply   it!)                                               !   
  !                                                                                                                                                           !   
  !-------------------------SLOW   PERFORMANCE   FORMATS----------------------------!   
  !   %d   -   date   and   time,   also   %d{ISO8601},   %d{DATE},   %d{ABSOLUTE},                               !   
  !                 %d{HH:mm:ss,SSS},   %d{dd   MMM   yyyy   HH:mm:ss,SSS}   and   so   on                           !   
  !   %l   -   Shortcut   for   %F%L%C%M                                                                                                     !   
  !   %F   -   Java   source   file   name                                                                                                     !   
  !   %L   -   Java   source   line   number                                                                                                 !   
  !   %C   -   Java   class   name,   %C{1}   will   output   the   last   one   component                             !   
  !   %M   -   Java   method   name                                                                                                               !   
  !                                                                                                                                                           !   
  !------------------------------FORMAT   MODIFIERS-------------------------------!   
  !   %-any_letter_above   -   Left-justify   in   min.   width   (default   is   right-justify)     !   
  !   %20any_letter_above   -   20   char.   min.   width   (pad   with   spaces   if   reqd.)                 !   
  !   %.30any_letter_above   -   30   char.   max.   width   (truncate   beginning   if   reqd.)         !   
  !   %-10.10r   -   Example.     Left-justify   time   elapsed   within   10-wide   field.                 !   
  !                             Truncate   from   beginning   if   wider   than   10   characters.                       !   
  !-----------------------------------------------------------------------------!   
  Let life be beautiful like summer flowers and death like autumn leaves.