javolution37.javolution.realtime

Class LogContext

java.lang.Object

javolution37.javolution.realtime.Context

javolution37.javolution.realtime.LogContext

Direct Known Subclasses:

StandardLog

public abstract class LogContext
extends Context

This class represents a logging context; it allows for object-based/thread-based logging and logging specializations (such as StandardLog to leverage java.util.logging capabilities).

The default logging context is STANDARD (log events forwarded to the root java.util.logging.Logger). Users may changes the default logging for all threads:

     // Logging disabled by default.
     LogContext.setDefault(LogContext.NULL); 
     

and/or perform custom logging for particular objects/threads:

     LogContext.enter(LogContext.SYSTEM);
     try {
        LogContext.info("Writes this message to System.out");
        ...       
     } finally {
        LogContext.exit(LogContext.SYSTEM);
     }

Applications may extend this base class to address specific logging requirements. For example:

     // This class allows for custom logging of session events. 
     public abstract class SessionLog extends LogContext  {
         public static void start(Session session) {
             LogContext log = LogContext.current();
             if (log instanceof SessionLog.Loggable) { 
                 ((SessionLog.Loggable)log).logStart(session);
             } else if (log.isInfoLogged()) {
                 log.logInfo("Session " + session.id() + " started");
             }
         }
         public static void end(Session session) { ... }
         public interface Loggable { 
             void logStart(Session session);
             void logEnd(Session session);
         }
     }

The use of interfaces (such as Loggable above) makes it easy for any context to support customs logging events. For example:

     class MyLog extends StandardLog implements SessionLog.Loggable, DatabaseLog.Loggable { 
         ...   // Specialized logging for session and database events. 
     }
     MyLog myLog = new MyLog();
     LogContext.enter(myLog);
     try {
         ...
         LogContext.info("Informative message"); // Standard logging.   
         ...
         DatabaseLog.fail(transaction); // Database custom logging.
         ... 
         SessionLog.start(session); // Session custom logging.
         ...
     } finally {
         LogContext.exit(myLog);
     }

Field Summary

Fields

Modifier and Type	Field and Description
static LogContext	NULL Holds a context ignoring logging events.
static StandardLog	STANDARD Holds a context forwarding log events to the root java.util.logging.Logger framework (default logging context).
static LogContext	SYSTEM Holds a context logging informative messages to System.out and warnings/errors events to System.err.
static LogContext	SYSTEM_ERR Holds a context logging warnings/errors events to System.err and ignoring informative messages.

Constructor Summary

Constructors

Constructor and Description
LogContext() Default constructor.

Method Summary

Modifier and Type	Method and Description
static LogContext	current() Returns the current logging context (or getDefault() if the current thread has not entered any logging context).
static void	error(java.lang.Throwable error) Logs the specified error to the current logging context.
static void	error(java.lang.Throwable error, java.lang.CharSequence message) Logs the specified error and error message to the current logging context.
static LogContext	getDefault() Returns the default logging context for new threads (STANDARD when not explicitly set).
static void	info(java.lang.CharSequence message) Logs the specified informative message.
abstract boolean	isErrorLogged() Indicates if errors are logged.
abstract boolean	isInfoLogged() Indicates if informative messages are logged.
abstract boolean	isWarningLogged() Indicates if warning messages are logged.
abstract void	logError(java.lang.Throwable error, java.lang.CharSequence message) Logs the specified error.
abstract void	logInfo(java.lang.CharSequence message) Logs the specified informative message.
abstract void	logWarning(java.lang.CharSequence message) Logs the specified warning message.
static void	setDefault(LogContext defaultLog) Sets the specified logging context as default.
static void	warning(java.lang.CharSequence message) Logs the specified warning message to the current logging context.

Methods inherited from class javolution37.javolution.realtime.Context

clear, enter, exit, getOuter, getOwner

Methods inherited from class java.lang.Object

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

Field Detail

STANDARD

public static final StandardLog STANDARD

Holds a context forwarding log events to the root java.util.logging.Logger framework (default logging context). The info/warning/error events are mapped to the info/warning/severe log levels respectively.

NULL

public static final LogContext NULL

Holds a context ignoring logging events.

SYSTEM

public static final LogContext SYSTEM

Holds a context logging informative messages to System.out and warnings/errors events to System.err.

SYSTEM_ERR

public static final LogContext SYSTEM_ERR

Holds a context logging warnings/errors events to System.err and ignoring informative messages.

Constructor Detail

LogContext

public LogContext()

Default constructor.

Method Detail

current

public static LogContext current()

Returns the current logging context (or getDefault() if the current thread has not entered any logging context).

Returns:

the current logging context.

getDefault

public static LogContext getDefault()

Returns the default logging context for new threads (STANDARD when not explicitly set).

Returns:

the default logging contexts.

setDefault

public static void setDefault(LogContext defaultLog)

Sets the specified logging context as default.

Parameters:

defaultLog - the default logging context.

info

public static void info(java.lang.CharSequence message)

Logs the specified informative message.

Parameters:

message - the informative message being logged.

See Also:

logInfo(CharSequence)

warning

public static void warning(java.lang.CharSequence message)

Logs the specified warning message to the current logging context.

Parameters:

message - the warning message being logged.

See Also:

logWarning(CharSequence)

error

public static void error(java.lang.Throwable error)

Logs the specified error to the current logging context.

Parameters:

error - the error being logged.

error

public static void error(java.lang.Throwable error,
                         java.lang.CharSequence message)

Logs the specified error and error message to the current logging context.

Parameters:

error - the error being logged.

message - the supplementary message or null if none.

isInfoLogged

public abstract boolean isInfoLogged()

Indicates if informative messages are logged.

Returns:

true if informative messages are logged; false otherwise.

logInfo

public abstract void logInfo(java.lang.CharSequence message)

Logs the specified informative message.

Parameters:

message - the informative message being logged.

isWarningLogged

public abstract boolean isWarningLogged()

Indicates if warning messages are logged.

Returns:

true if warnings message are logged; false otherwise.

logWarning

public abstract void logWarning(java.lang.CharSequence message)

Logs the specified warning message.

Parameters:

message - the warning message being logged.

isErrorLogged

public abstract boolean isErrorLogged()

Indicates if errors are logged.

Returns:

true if errors are logged; false otherwise.

logError

public abstract void logError(java.lang.Throwable error,
                              java.lang.CharSequence message)

Logs the specified error.

Parameters:

error - the error being logged.

message - the associated message or null if none.