A Handler takes LogRecord
objects from a Logger and, if their severity level
is high enough, formats and publishes them to some destination (a
file or socket, for example). The subclasses of this abstract class
support various destinations, and implement destination-specific
publish( ), flush( ) and
close( ) methods.
In addition to the destination-specific abstract methods, this class
also defines concrete methods used by most Handler
subclasses. These are property getter and setter methods to specify
the severity Level of logging messages to be
handled, an optional Filter, a
Formatter to convert log messages from
LogRecord objects to text, a text encoding for the
output text, and an ErrorManager to handle any
exceptions that arise during log output. Subclass-specific defaults
for each of these properties are typically defined as properties of
LogManager and are read from a system-wide logging configuration
file.
In the simplest uses of the Logging API, a Logger
sends it log messages to one or more handlers defined by the
LogManager class for its "root
logger". In this case there is no need for the
application to ever instantiate or use a Handler
directly. Applications that want custom control over the destination
of their logs create and configure an instance of a
Handler subclass, but never need to call its
publish( ), flush( ) or
close( ) methods directly: that is done by the
Logger.
public abstract class
Handler {
// Protected Constructors
protected
Handler ( );
// Public Instance Methods
public abstract void
close ( ) throws SecurityException;
public abstract void
flush ( );
public String
getEncoding ( );
public ErrorManager
getErrorManager ( );
public Filter
getFilter ( );
public java.util.logging.Formatter
getFormatter ( );
public Level
getLevel ( ); synchronized
public boolean
isLoggable (LogRecord
record );
public abstract void
publish (LogRecord
record );
public void
setEncoding (String
encoding ) throws SecurityException,
java.io.UnsupportedEncodingException;
public void
setErrorManager (ErrorManager
em );
public void
setFilter (Filter
newFilter ) throws SecurityException;
public void
setFormatter (java.util.logging.Formatter
newFormatter )
throws SecurityException;
public void
setLevel (Level
newLevel ) throws SecurityException; synchronized
// Protected Instance Methods
protected void
reportError (String
msg , Exception
ex , int
code );
}
java.util.logging.Formatter.{getHead( ),
getTail( )}, Logger.{addHandler(
), removeHandler( )},
MemoryHandler.MemoryHandler( ),
XMLFormatter.{getHead( ), getTail(
)}