Module: RJack::SLF4J

Defined in:
lib/rjack-slf4j.rb,
lib/rjack-slf4j/mdc.rb,
lib/rjack-slf4j/base.rb

Overview

Wrapper and core Logger compatible adapter for the SLF4J logging interface.

Usage

require 'rjack-slf4j'

log = RJack::SLF4J[ "my.app.logger" ]
log.info "Hello World!"

Adapters

An output adapter must be required before the first log call. All of the following output adapters are available via require from the slf4j gem:

require 'rjack-slf4j/jcl'       # Output to Jakarta Commons Logging
require 'rjack-slf4j/jdk14'     # JDK java.util.logging (JUL)
require 'rjack-slf4j/log4j12'   # Log4j (provided elsewhere)
require 'rjack-slf4j/nop'       # NOP null logger (provided)
require 'rjack-slf4j/simple'    # Simple logger (provided)

The rjack-logback gem may also be be used as the output adapter:

require 'rjack-logback'

The first loaded output adapter wins (as with multiple adapters on the classpath). A warning will be logged to “slf4j” if an attempt is made to require a second output adapter.

The following input adapters will intercept JCL, java.util.logging (JUL), or log4j log output and direct it through SLF4J:

require 'rjack-slf4j/jcl-over-slf4j'   # Route Jakarta Commons Logging to SLF4J
require 'rjack-slf4j/log4j-over-slf4j' # Log4j to SLF4J

require 'rjack-slf4j/jul-to-slf4j'     # JDK java.util.logging (JUL) to SLF4J
RJack::SLF4J::JUL.replace_root_handlers # Special case setup for JUL

Multiple input adapters may be require’d. However, a RuntimeError will be raised in the attempt to require both an output adapter and input adapter from/to the same interface, for example ‘rjack-slf4j/jcl-over-slf4j’ and ‘rjack-slf4j/jcl’, which would otherwise cause a circular logging loop (and stack overflow.)

Adapter names match the corresponding SLF4J jars.

Defined Under Namespace

Modules: JUL, MDC Classes: Logger

Constant Summary collapse

LEVELS =

SLF4J severity levels

%w{ trace debug info warn error }
SLF4J_VERSION =

SLF4J-java version

'1.7.7'
VERSION =

SLF4J gem version

SLF4J_VERSION + '.1'
SLF4J_DIR =

:nodoc:

File.dirname(__FILE__)
ADAPTERS =

:input :output (jar with slf4j- prefix)

[ [ "jul-to-slf4j",     "jdk14"   ],
[ "jcl-over-slf4j",   "jcl"     ],
[ "log4j-over-slf4j", "log4j12" ],
[ nil,                "nop"     ],
[ nil,                "simple"  ] ]
@@api_loader = 
org.slf4j.ILoggerFactory.java_class.class_loader
@@loaded = 
{}
@@output_name = 
nil

Class Method Summary collapse

Class Method Details

.[](name) ⇒ Object

Synonym for Logger.new( name )



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# File 'lib/rjack-slf4j.rb', line 330

def self.[]( name )
  Logger.new( name )
end

.linked_factory ⇒ Object

The ILoggerFactory instance if an output adapter has been loaded



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# File 'lib/rjack-slf4j.rb', line 335

def self.linked_factory
   org.slf4j.LoggerFactory.getILoggerFactory
end

.logger(name = self.class.name) ⇒ Object

Get Logger by name



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# File 'lib/rjack-slf4j.rb', line 324

def logger( name = self.class.name )
  Logger.new( name )
end

.output_name ⇒ Object

Output adapter name if one has been added, or nil.



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# File 'lib/rjack-slf4j.rb', line 128

def self.output_name
  @@output_name
end

.require_adapter(name) ⇒ Object

Require an adapter by name (add the jar to classpath) This is normally done via require ‘slf4j/name’



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# File 'lib/rjack-slf4j.rb', line 82

def self.require_adapter( name )
  row = ADAPTERS.assoc( name )
  if row
    name,ban = row
    output = false
  else
    row = ADAPTERS.rassoc( name )
    ban,name = row
    output = true
  end

  if @@loaded[ ban ]
    raise "Illegal attempt to load '#{name}' when '#{ban}' is loaded."
  end

  if output
    if ! @@output_name.nil? && name != @@output_name
      logger("slf4j").warn do
        "Ignoring attempt to load #{name} after #{@@output_name} already loaded."
      end
      return
    end
    if java.lang.Thread::current_thread.context_class_loader != @@api_loader
      $stderr.puts( "WARNING: Attempting to load #{name} in child class" +
                    " loader of slf4j-api.jar loader." )
    end
    require_jar( 'slf4j-' + name )
    @@output_name = name
  else
    require_jar( name )
  end

  @@loaded[ name ] = true
end

.require_jar(name) ⇒ Object

:nodoc:



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# File 'lib/rjack-slf4j.rb', line 117

def self.require_jar( name ) # :nodoc:
  require File.join( SLF4J_DIR, "#{name}-#{ SLF4J_VERSION }.jar" )
end

.to_log_name(clz) ⇒ Object Also known as: ruby_to_java_logger_name

Return a java style class name, suitable as a logger name, from the given ruby class or module, i.e:

to_log_name( Foo::Bar::Baz ) --> "foo.bar.Baz"



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# File 'lib/rjack-slf4j.rb', line 140

def self.to_log_name( clz )
  clz.name.gsub( /::/, '.' ).gsub( /([^\.]+)\./ ) { |m| m.downcase }
end