Handler

public abstract class Handler extends Object

Known Direct Subclasses MemoryHandler, StreamHandler MemoryHandler Handler that buffers requests in a circular buffer in memory.  StreamHandler Stream based logging Handler.

Known Indirect Subclasses ConsoleHandler, FileHandler ConsoleHandler This Handler publishes log records to System.err.  FileHandler Simple file logging Handler.

A Handler object takes log messages from a Logger and exports them. It might for example, write them to a console or write them to a file, or send them to a network logging service, or forward them to an OS log, or whatever.

A Handler can be disabled by doing a setLevel(Level.OFF) and can be re-enabled by doing a setLevel with an appropriate level.

Handler classes typically use LogManager properties to set default values for the Handler's Filter, Formatter, and Level. See the specific documentation for each concrete Handler class.

Protected Constructor Summary

Handler() Default constructor.

Public Method Summary

abstract void	close() Close the Handler and free all associated resources.
abstract void	flush() Flush any buffered output.
String	getEncoding() Return the character encoding for this Handler.
ErrorManager	getErrorManager() Retrieves the ErrorManager for this Handler.
Filter	getFilter() Get the current Filter for this Handler.
Formatter	getFormatter() Return the Formatter for this Handler.
Level	getLevel() Get the log level specifying which messages will be logged by this Handler.
boolean	isLoggable(LogRecord record) Check if this Handler would actually log a given LogRecord.
abstract void	publish(LogRecord record) Publish a LogRecord.
synchronized void	setEncoding(String encoding) Set the character encoding used by this Handler.
synchronized void	setErrorManager(ErrorManager em) Define an ErrorManager for this Handler.
synchronized void	setFilter(Filter newFilter) Set a Filter to control output on this Handler.
synchronized void	setFormatter(Formatter newFormatter) Set a Formatter.
synchronized void	setLevel(Level newLevel) Set the log level specifying which message levels will be logged by this Handler.

Protected Method Summary

void	reportError(String msg, Exception ex, int code) Protected convenience method to report an error to this Handler's ErrorManager.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Protected Constructors

protected Handler ()

Default constructor. The resulting Handler has a log level of Level.ALL, no Formatter, and no Filter. A default ErrorManager instance is installed as the ErrorManager.

Public Methods

public abstract void close ()

Close the Handler and free all associated resources.

The close method will perform a flush and then close the Handler. After close has been called this Handler should no longer be used. Method calls may either be silently ignored or may throw runtime exceptions.

Throws

SecurityException	if a security manager exists and if the caller does not have LoggingPermission("control").

public abstract void flush ()

Flush any buffered output.

public String getEncoding ()

Return the character encoding for this Handler.

Returns

• The encoding name. May be null, which indicates the default encoding should be used.

public ErrorManager getErrorManager ()

Retrieves the ErrorManager for this Handler.

Returns

• the ErrorManager for this Handler

Throws

SecurityException	if a security manager exists and if the caller does not have LoggingPermission("control").

public Filter getFilter ()

Get the current Filter for this Handler.

Returns

• a Filter object (may be null)

public Formatter getFormatter ()

Return the Formatter for this Handler.

Returns

• the Formatter (may be null).

public Level getLevel ()

Get the log level specifying which messages will be logged by this Handler. Message levels lower than this level will be discarded.

Returns

• the level of messages being logged.

public boolean isLoggable (LogRecord record)

Check if this Handler would actually log a given LogRecord.

This method checks if the LogRecord has an appropriate Level and whether it satisfies any Filter. It also may make other Handler specific checks that might prevent a handler from logging the LogRecord. It will return false if the LogRecord is null.

Parameters

record	a LogRecord

Returns

• true if the LogRecord would be logged.

public abstract void publish (LogRecord record)

Publish a LogRecord.

The logging request was made initially to a Logger object, which initialized the LogRecord and forwarded it here.

The Handler is responsible for formatting the message, when and if necessary. The formatting should include localization.

Parameters

record	description of the log event. A null record is silently ignored and is not published

public synchronized void setEncoding (String encoding)

Set the character encoding used by this Handler.

The encoding should be set before any LogRecords are written to the Handler.

Parameters

encoding	The name of a supported character encoding. May be null, to indicate the default platform encoding.

Throws

SecurityException	if a security manager exists and if the caller does not have LoggingPermission("control").
UnsupportedEncodingException	if the named encoding is not supported.

public synchronized void setErrorManager (ErrorManager em)

Define an ErrorManager for this Handler.

The ErrorManager's "error" method will be invoked if any errors occur while using this Handler.

Parameters

em	the new ErrorManager

Throws

SecurityException	if a security manager exists and if the caller does not have LoggingPermission("control").

public synchronized void setFilter (Filter newFilter)

Set a Filter to control output on this Handler.

For each call of publish the Handler will call this Filter (if it is non-null) to check if the LogRecord should be published or discarded.

Parameters

newFilter	a Filter object (may be null)

Throws

SecurityException	if a security manager exists and if the caller does not have LoggingPermission("control").

public synchronized void setFormatter (Formatter newFormatter)

Set a Formatter. This Formatter will be used to format LogRecords for this Handler.

Some Handlers may not use Formatters, in which case the Formatter will be remembered, but not used.

Parameters

newFormatter	the Formatter to use (may not be null)

Throws

SecurityException	if a security manager exists and if the caller does not have LoggingPermission("control").

public synchronized void setLevel (Level newLevel)

Set the log level specifying which message levels will be logged by this Handler. Message levels lower than this value will be discarded.

The intention is to allow developers to turn on voluminous logging, but to limit the messages that are sent to certain Handlers.

Parameters

newLevel	the new value for the log level

Throws

SecurityException	if a security manager exists and if the caller does not have LoggingPermission("control").

Protected Methods

protected void reportError (String msg, Exception ex, int code)

Protected convenience method to report an error to this Handler's ErrorManager. Note that this method retrieves and uses the ErrorManager without doing a security check. It can therefore be used in environments where the caller may be non-privileged.

Parameters

msg	a descriptive string (may be null)
ex	an exception (may be null)
code	an error code defined in ErrorManager