org.apache.log4j
Class AppenderSkeleton

java.lang.Object
  org.apache.log4j.AppenderSkeleton

All Implemented Interfaces:

Appender, OptionHandler

Direct Known Subclasses:

AsyncAppender, JDBCAppender, JMSAppender, LF5Appender, NTEventLogAppender, NullAppender, SMTPAppender, SocketAppender, SocketHubAppender, SyslogAppender, TelnetAppender, WriterAppender

public abstract class AppenderSkeleton
extends Object
implements Appender, OptionHandler

Abstract superclass of the other appenders in the package. This class provides the code for common functionality, such as support for threshold filtering and support for general filters.

Since:

0.8.1

Author:

Ceki Gülcü

Field Summary

protected boolean	closed Is this appender closed?
protected ErrorHandler	errorHandler It is assumed and enforced that errorHandler is never null.
protected Filter	headFilter The first filter in the filter chain.
protected Layout	layout The layout variable does not need to be set if the appender implementation has its own layout.
protected String	name Appenders are named.
protected Filter	tailFilter The last filter in the filter chain.
protected Priority	threshold There is no level threshold filtering by default.

Constructor Summary

	AppenderSkeleton() Create new instance.
protected	AppenderSkeleton(boolean isActive) Create new instance.

Method Summary

void	activateOptions() Derived appenders should override this method if option structure requires it.
void	addFilter(Filter newFilter) Add a filter to end of the filter list.
protected abstract void	append(LoggingEvent event) Subclasses of AppenderSkeleton should implement this method to perform actual logging.
void	clearFilters() Clear the filters chain.
void	doAppend(LoggingEvent event) This method performs threshold checks and invokes filters before delegating actual logging to the subclasses specific append(org.apache.log4j.spi.LoggingEvent) method.
void	finalize() Finalize this appender by calling the derived class' close method.
ErrorHandler	getErrorHandler() Return the currently set ErrorHandler for this Appender.
Filter	getFilter() Returns the head Filter.
Filter	getFirstFilter() Return the first filter in the filter chain for this Appender.
Layout	getLayout() Returns the layout of this appender.
String	getName() Returns the name of this appender.
Priority	getThreshold() Returns this appenders threshold level.
boolean	isAsSevereAsThreshold(Priority priority) Check whether the message level is below the appender's threshold.
void	setErrorHandler(ErrorHandler eh) Set the ErrorHandler for this Appender.
void	setLayout(Layout layout) Set the layout for this appender.
void	setName(String name) Set the name of this Appender.
void	setThreshold(Priority threshold) Set the threshold level.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.log4j.Appender

close, requiresLayout

Field Detail

layout

protected Layout layout

The layout variable does not need to be set if the appender implementation has its own layout.

name

protected String name

Appenders are named.

threshold

protected Priority threshold

There is no level threshold filtering by default.

errorHandler

protected ErrorHandler errorHandler

It is assumed and enforced that errorHandler is never null.

headFilter

protected Filter headFilter

The first filter in the filter chain. Set to null initially.

tailFilter

protected Filter tailFilter

The last filter in the filter chain.

closed

protected boolean closed

Is this appender closed?

Constructor Detail

AppenderSkeleton

public AppenderSkeleton()

Create new instance.

AppenderSkeleton

protected AppenderSkeleton(boolean isActive)

Create new instance. Provided for compatibility with log4j 1.3.

Parameters:

isActive - true if appender is ready for use upon construction. Not used in log4j 1.2.x.

Since:

1.2.15

Method Detail

activateOptions

public void activateOptions()

Derived appenders should override this method if option structure requires it.

Specified by:

activateOptions in interface OptionHandler

addFilter

public void addFilter(Filter newFilter)

Add a filter to end of the filter list.

Specified by:

addFilter in interface Appender

Since:

0.9.0

append

protected abstract void append(LoggingEvent event)

Subclasses of AppenderSkeleton should implement this method to perform actual logging. See also AppenderSkeleton.doAppend method.

Since:

0.9.0

clearFilters

public void clearFilters()

Clear the filters chain.

Specified by:

clearFilters in interface Appender

Since:

0.9.0

finalize

public void finalize()

Finalize this appender by calling the derived class' close method.

Overrides:

finalize in class Object

Since:

0.8.4

getErrorHandler

public ErrorHandler getErrorHandler()

Return the currently set ErrorHandler for this Appender.

Specified by:

getErrorHandler in interface Appender

Since:

0.9.0

getFilter

public Filter getFilter()

Returns the head Filter.

Specified by:

getFilter in interface Appender

Returns:

the head Filter or null, if no Filters are present

Since:

1.1

getFirstFilter

public final Filter getFirstFilter()

Return the first filter in the filter chain for this Appender. The return value may be null if no is filter is set.

getLayout

public Layout getLayout()

Returns the layout of this appender. The value may be null.

Specified by:

getLayout in interface Appender

getName

public final String getName()

Returns the name of this appender.

Specified by:

getName in interface Appender

Returns:

name, may be null.

getThreshold

public Priority getThreshold()

Returns this appenders threshold level. See the setThreshold(org.apache.log4j.Priority) method for the meaning of this option.

Since:

1.1

isAsSevereAsThreshold

public boolean isAsSevereAsThreshold(Priority priority)

Check whether the message level is below the appender's threshold. If there is no threshold set, then the return value is always true.

doAppend

public void doAppend(LoggingEvent event)

This method performs threshold checks and invokes filters before delegating actual logging to the subclasses specific append(org.apache.log4j.spi.LoggingEvent) method.

Specified by:

doAppend in interface Appender

setErrorHandler

public void setErrorHandler(ErrorHandler eh)

Set the ErrorHandler for this Appender.

Specified by:

setErrorHandler in interface Appender

Since:

0.9.0

setLayout

public void setLayout(Layout layout)

Set the layout for this appender. Note that some appenders have their own (fixed) layouts or do not use one. For example, the SocketAppender ignores the layout set here.

Specified by:

setLayout in interface Appender

setName

public void setName(String name)

Set the name of this Appender.

Specified by:

setName in interface Appender

setThreshold

public void setThreshold(Priority threshold)

Set the threshold level. All log events with lower level than the threshold level are ignored by the appender.

In configuration files this option is specified by setting the value of the Threshold option to a level string, such as "DEBUG", "INFO" and so on.

Since:

0.8.3