Package org.apache.logging.log4j.core

Interface Appender

All Superinterfaces:

LifeCycle

All Known Implementing Classes:

AbstractAppender, AbstractDatabaseAppender, AbstractFileAppender, AbstractOutputStreamAppender, AbstractWriterAppender, AsyncAppender, ConsoleAppender, CountingNoOpAppender, FailoverAppender, FileAppender, HttpAppender, JdbcAppender, JeroMqAppender, JmsAppender, KafkaAppender, MemoryMappedFileAppender, NoSqlAppender, NullAppender, OutputStreamAppender, RandomAccessFileAppender, RewriteAppender, RollingFileAppender, RollingRandomAccessFileAppender, RoutingAppender, ScriptAppenderSelector, SmtpAppender, SocketAppender, SyslogAppender, WriterAppender

public interface Appender
extends LifeCycle

Appends LogEvents. An Appender can contain a Layout if applicable as well as an ErrorHandler. Typical Appender implementations coordinate with an implementation of AbstractManager to handle external resources such as streams, connections, and other shared state. As Appenders are plugins, concrete implementations need to be annotated with Plugin and need to provide a static factory method annotated with PluginFactory.

Most core plugins are written using a related Manager class that handle the actual task of serializing a LogEvent to some output location. For instance, many Appenders can take advantage of the OutputStreamManager class.

It is recommended that Appenders don't do any heavy lifting since there can be many instances of the class being used at any given time. When resources require locking (e.g., through FileLock), it is important to isolate synchronized code to prevent concurrency issues.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.logging.log4j.core.LifeCycle

LifeCycle.State

Field Summary

Fields

Modifier and Type	Field	Description
static final String	ELEMENT_TYPE	Main plugin element type for Appender plugins.
static final Appender[]	EMPTY_ARRAY	Empty array.

Method Summary

Modifier and Type	Method	Description
void	append(LogEvent event)	Logs a LogEvent using whatever logic this Appender wishes to use.
ErrorHandler	getHandler()	Gets the ErrorHandler used for handling exceptions.
Layout<? extends Serializable>	getLayout()	Returns the Layout used by this Appender if applicable.
String	getName()	Gets the name of this Appender.
boolean	ignoreExceptions()	Some Appenders need to propagate exceptions back to the application.
void	setHandler(ErrorHandler handler)	Sets the ErrorHandler used for handling exceptions.

Methods inherited from interface org.apache.logging.log4j.core.LifeCycle

getState, initialize, isStarted, isStopped, start, stop

Field Details

ELEMENT_TYPE

static final String ELEMENT_TYPE

Main plugin element type for Appender plugins.

Since:

2.6

See Also:

• Constant Field Values

EMPTY_ARRAY

static final Appender[] EMPTY_ARRAY

Empty array.

Method Details

append

void append(LogEvent event)

Logs a LogEvent using whatever logic this Appender wishes to use. It is typically recommended to use a bridge pattern not only for the benefits from decoupling an Appender from its implementation, but it is also handy for sharing resources which may require some form of locking.

Parameters:

event - The LogEvent.

getName

String getName()

Gets the name of this Appender.

Returns:

name, may be null.

getLayout

Layout<? extends Serializable> getLayout()

Returns the Layout used by this Appender if applicable.

Returns:

the Layout for this Appender or null if none is configured.

ignoreExceptions

boolean ignoreExceptions()

Some Appenders need to propagate exceptions back to the application. When ignoreExceptions is false the AppenderControl will allow the exception to percolate.

Returns:

true if exceptions will be logged but not thrown, false otherwise.

getHandler

ErrorHandler getHandler()

Gets the ErrorHandler used for handling exceptions.

Returns:

the ErrorHandler for handling exceptions.

setHandler

void setHandler(ErrorHandler handler)

Sets the ErrorHandler used for handling exceptions.

Parameters:

handler - the ErrorHandler to use for handling exceptions.