Class Logger
- All Implemented Interfaces:
EventListener
,ServiceListener
This class mimics the standard OSGi LogService interface. An instance of this class is used by the framework for all logging. By default this class logs messages to standard out. The log level can be set to control the amount of logging performed, where a higher number results in more logging. A log level of zero turns off logging completely.
The log levels match those specified in the OSGi Log Service (i.e., 1 = error, 2 = warning, 3 = information, and 4 = debug). The default value is 1.
This class also uses the System Bundle's context to track log services and will use the highest ranking log service, if present, as a back end instead of printing to standard out. The class uses reflection to invoking the log service's method to avoid a dependency on the log interface.
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final int
static final int
static final int
static final int
private static final int
private static final int
private BundleContext
private Object[]
private int
private ServiceReference
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate void
_log
(Bundle bundle, ServiceReference sr, int level, String msg, Throwable throwable) private void
_logReflectively
(Object[] logger, ServiceReference sr, int level, String msg, Throwable throwable) protected void
doLog
(Bundle bundle, ServiceReference sr, int level, String msg, Throwable throwable) final int
final void
final void
final void
final void
final void
log
(ServiceReference sr, int level, String msg) final void
log
(ServiceReference sr, int level, String msg, Throwable throwable) final void
serviceChanged
(ServiceEvent event) This method implements the callback for the ServiceListener interface.private void
This method sets the new log service object.final void
setLogLevel
(int i) protected void
setSystemBundleContext
(BundleContext context) private void
This method is called when the system bundle context is set; it simply adds a service listener so that the system bundle can track log services to be used as the back end of the logging mechanism.
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Field Details
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LOG_ERROR
public static final int LOG_ERROR- See Also:
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LOG_WARNING
public static final int LOG_WARNING- See Also:
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LOG_INFO
public static final int LOG_INFO- See Also:
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LOG_DEBUG
public static final int LOG_DEBUG- See Also:
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m_logLevel
private int m_logLevel -
m_context
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LOGGER_OBJECT_IDX
private static final int LOGGER_OBJECT_IDX- See Also:
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LOGGER_METHOD_IDX
private static final int LOGGER_METHOD_IDX- See Also:
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m_logRef
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m_logger
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Constructor Details
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Logger
public Logger()
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Method Details
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setLogLevel
public final void setLogLevel(int i) -
getLogLevel
public final int getLogLevel() -
setSystemBundleContext
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log
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log
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log
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log
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log
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log
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doLog
protected void doLog(Bundle bundle, ServiceReference sr, int level, String msg, Throwable throwable) -
_log
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_logReflectively
private void _logReflectively(Object[] logger, ServiceReference sr, int level, String msg, Throwable throwable) -
startListeningForLogService
private void startListeningForLogService()This method is called when the system bundle context is set; it simply adds a service listener so that the system bundle can track log services to be used as the back end of the logging mechanism. It also attempts to get an existing log service, if present, but in general there will never be a log service present since the system bundle is started before every other bundle. -
serviceChanged
This method implements the callback for the ServiceListener interface. It is public as a byproduct of implementing the interface and should not be called directly. This method tracks run-time changes to log service availability. If the log service being used by the framework's logging mechanism goes away, then this will try to find an alternative. If a higher ranking log service is registered, then this will switch to the higher ranking log service.- Specified by:
serviceChanged
in interfaceServiceListener
- Parameters:
event
- TheServiceEvent
object.
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setLogger
This method sets the new log service object. It also caches the method to invoke. The service object and method are stored in array to optimistically eliminate the need to locking when logging.
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