Java in a Nutshell, 5th Edition [Electronic resources] نسخه متنی

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 );
}

Subclasses

MemoryHandler, StreamHandler

Passed To

java.util.logging.Formatter.{getHead( ),
getTail( )}, Logger.{addHandler(
), removeHandler( )},
MemoryHandler.MemoryHandler( ),
XMLFormatter.{getHead( ), getTail(
)}

Returned By

Logger.getHandlers( )