javolution.context

Class LogContext

java.lang.Object

javolution.context.AbstractContext

javolution.context.LogContext

public abstract class LogContext
extends AbstractContext

Asynchronous logging context integrated with the OSGi logging framework. The logging back-end, or how the log entries are displayed, stored, or processed is unspecified but always performed asynchronously. When running outside OSGi, log messages are sent to System.out. Message formatting itself is always performed synchronously using the current TextContext.

Logging contexts support automatic prefixing/suffixing of any information relevant to the user/developer (thread info, user id, and so on).

 void run() {
     LogContext ctx = LogContext.enter(); 
     try {
         // Prefix the executing thread to any message being logged.
         ctx.prefix("[Thread: ", Thead.currentThread(), "] "); 
         ... 
      } finally {
         ctx.exit();
      }
  }

Applications should separate messages elements by commas and not use String concatenations when calling log methods otherwise the concatenation is performed even when log events are filtered out.

 LogContext ctx = LogContext.enter();
 try {
     ctx.setLevel(Level.INFO); // Does not log debug messages. 
     ... 
     LogContext.debug("Index: ", index, " at maximum value"); // GOOD, no formatting performed !
     LogContext.debug("Index: " + index + " at maximum value"); // BAD, formatting performed even though nothing is logged !
     ...
 } finally {
     ctx.exit();
 }

In general, the LogContext.Level.DEBUG level provides information only relevant to developers and can be turned off after deployment.

Version:

6.0, July 21, 2013

Author:

Jean-Marie Dautelle

See Also:

Understanding OSGi Logging

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LogContext.Level Defines the logging levels.

Field Summary

Fields

Modifier and Type	Field and Description
static Configurable<LogContext.Level>	LEVEL Holds the default logging level (INFO).

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LogContext() Default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
static void	debug(Object... message) Logs the specified debug message.
static LogContext	enter() Enters and returns a new log context instance.
static void	error(Object... message) Logs the specified error message (which may include any Throwable instance).
static void	info(Object... message) Logs the specified info message.
protected abstract void	log(LogContext.Level level, Object... message) Logs the specified message at the specified level.
abstract void	prefix(Object... prefixes) Prefixes all messages being logged by the specified prefixes (prefixing existing prefixes if any).
abstract void	setLevel(LogContext.Level level) Set the logging level, messages below that level are not logged.
abstract void	suffix(Object... suffixes) Suffixes all messages being logged by the specified suffixes (suffixing existing suffixes if any).
static void	warning(Object... message) Logs the specified warning message.

Methods inherited from class javolution.context.AbstractContext

current, current, enter, enterInner, exit, getOuter, inherit, inner

Methods inherited from class java.lang.Object

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

Field Detail

LEVEL

public static final Configurable<LogContext.Level> LEVEL

Holds the default logging level (INFO). This level is configurable. For example, running with the option -Djavolution.context.LogContext#LEVEL=WARNING causes the debug/info not to be logged.

Constructor Detail

LogContext

protected LogContext()

Default constructor.

Method Detail

debug

public static void debug(Object... message)

Logs the specified debug message.

enter

public static LogContext enter()

Enters and returns a new log context instance.

error

public static void error(Object... message)

Logs the specified error message (which may include any Throwable instance).

info

public static void info(Object... message)

Logs the specified info message.

warning

public static void warning(Object... message)

Logs the specified warning message.

prefix

public abstract void prefix(Object... prefixes)

Prefixes all messages being logged by the specified prefixes (prefixing existing prefixes if any).

setLevel

public abstract void setLevel(LogContext.Level level)

Set the logging level, messages below that level are not logged.

suffix

public abstract void suffix(Object... suffixes)

Suffixes all messages being logged by the specified suffixes (suffixing existing suffixes if any).

log

protected abstract void log(LogContext.Level level,
       Object... message)

Logs the specified message at the specified level.