Handler

public abstract class Handler extends Object
Known Direct Subclasses
Known Indirect Subclasses

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.
synchronized 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.
void
setEncoding(String encoding)
Set the character encoding used by this Handler.
void
setErrorManager(ErrorManager em)
Define an ErrorManager for this Handler.
void
setFilter(Filter newFilter)
Set a Filter to control output on this Handler.
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

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.

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 synchronized 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 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 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 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 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