# WriterAppender Class Reference

Inherits AppenderSkeleton.

Inherited by ConsoleAppender, and FileAppender.

List of all members.

## Detailed Description

WriterAppender appends log events to a standard output stream.

## Public Member Functions

| WriterAppender ()
| This default constructor does nothing.
| ~WriterAppender ()
virtual void | activateOptions (log4cxx::helpers::Pool &pool)
| Derived appenders should override this method if option structure requires it.
void | setImmediateFlush (bool value)
| If the ImmediateFlush option is set to `true`, the appender will flush at the end of each write.
bool | getImmediateFlush () const
| Returns value of the ImmediateFlush option.
virtual void | append (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &p)
| This method is called by the AppenderSkeleton::doAppend method.
virtual void | close ()
| Close this appender instance.
LogString | getEncoding () const
void | setEncoding (const LogString &value)
void | setOption (const LogString &option, const LogString &value)
| Set `option` to `value`.
void | setWriter (const log4cxx::helpers::WriterPtr &writer)
virtual bool | requiresLayout () const
| Configurators call this method to determine if the appender requires a layout.

## Protected Member Functions

| WriterAppender (const LayoutPtr &layout, log4cxx::helpers::WriterPtr &writer)
| WriterAppender (const LayoutPtr &layout)
virtual bool | checkEntryConditions () const
| This method determines if there is a sense in attempting to append.
void | closeWriter ()
| Close the underlying log4cxx::helpers::Writer.
virtual log4cxx::helpers::WriterPtr | createWriter (log4cxx::helpers::OutputStreamPtr &os)
| Returns an OutputStreamWriter when passed an OutputStream.
virtual void | subAppend (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &p)
| Actual writing occurs here.
virtual void | writeFooter (log4cxx::helpers::Pool &p)
| Write a footer as produced by the embedded layout's Layout::appendFooter method.
virtual void | writeHeader (log4cxx::helpers::Pool &p)
| Write a header as produced by the embedded layout's Layout::appendHeader method.

## Constructor & Destructor Documentation

WriterAppender | ( |  | ) |

| This default constructor does nothing.

WriterAppender | ( | const LayoutPtr & | layout,
|  | log4cxx::helpers::WriterPtr & | writer
| ) | `[protected]`

WriterAppender | ( | const LayoutPtr & | layout | ) | `[protected]`

~WriterAppender | ( |  | ) |

## Member Function Documentation

virtual void activateOptions | ( | log4cxx::helpers::Pool & | pool | ) | `[virtual]`

| Derived appenders should override this method if option structure requires it. Reimplemented from AppenderSkeleton. Reimplemented in ConsoleAppender, DailyRollingFileAppender, FileAppender, RollingFileAppenderSkeleton, and RollingFileAppender.

virtual void append | ( | const spi::LoggingEventPtr & | event,
|  | log4cxx::helpers::Pool & | p
| ) | `[virtual]`

| This method is called by the AppenderSkeleton::doAppend method. If the output stream exists and is writable then write a log statement to the output stream. Otherwise, write a single warning message to `stderr`. The format of the output will depend on this appender's layout. Implements AppenderSkeleton.

virtual bool checkEntryConditions | ( |  | ) | const`[protected, virtual]`

| This method determines if there is a sense in attempting to append. It checks whether there is a set output target and also if there is a set layout. If these checks fail, then the boolean value `false` is returned.

virtual void close | ( |  | ) | `[virtual]`

| Close this appender instance. The underlying stream or writer is also closed. Closed appenders cannot be reused. Implements Appender. Reimplemented in RollingFileAppenderSkeleton.

void closeWriter | ( |  | ) | `[protected]`

| Close the underlying log4cxx::helpers::Writer.

virtual log4cxx::helpers::WriterPtr createWriter | ( | log4cxx::helpers::OutputStreamPtr & | os | ) | `[protected, virtual]`

| Returns an OutputStreamWriter when passed an OutputStream. The encoding used will depend on the value of the `encoding` property. If the encoding value is specified incorrectly the writer will be opened using the default system encoding (an error message will be printed to the loglog. Reimplemented in RollingFileAppenderSkeleton.

LogString getEncoding | ( |  | ) | const

bool getImmediateFlush | ( |  | ) | const`[inline]`

| Returns value of the ImmediateFlush option.

virtual bool requiresLayout | ( |  | ) | const`[virtual]`

Configurators call this method to determine if the appender requires a layout.

If this method returns `true`, meaning that layout is required, then the configurator will configure an layout using the configuration information at its disposal. If this method returns `false`, meaning that a layout is not required, then layout configuration will be skipped even if there is available layout configuration information at the disposal of the configurator..

In the rather exceptional case, where the appender implementation admits a layout but can also work without it, then the appender should return `true`.

Implements Appender.

void setEncoding | ( | const LogString & | value | ) |

void setImmediateFlush | ( | bool | value | ) |

If the ImmediateFlush option is set to `true`, the appender will flush at the end of each write.

This is the default behavior. If the option is set to `false`, then the underlying stream can defer writing to physical medium to a later time.

Avoiding the flush operation at the end of each append results in a performance gain of 10 to 20 percent. However, there is safety tradeoff involved in skipping flushing. Indeed, when flushing is skipped, then it is likely that the last few log events will not be recorded on disk when the application exits. This is a high price to pay even for a 20% performance gain.

void setOption | ( | const LogString & | option,
|  | const LogString & | value
| ) | `[virtual]`

| Set `option` to `value`. The handling of each option depends on the OptionHandler instance. Some options may become active immediately whereas other may be activated only when activateOptions is called. Reimplemented from AppenderSkeleton. Reimplemented in ConsoleAppender, DailyRollingFileAppender, FileAppender, and RollingFileAppender.

void setWriter | ( | const log4cxx::helpers::WriterPtr & | writer | ) |

Sets the Writer where the log output will go. The specified Writer must be opened by the user and be writable.

The `java.io.Writer` will be closed when the appender instance is closed.

WARNING: Logging to an unopened Writer will fail.

Parameters:

  | writer | An already opened Writer.

virtual void subAppend | ( | const spi::LoggingEventPtr & | event,
|  | log4cxx::helpers::Pool & | p
| ) | `[protected, virtual]`

| Actual writing occurs here. Reimplemented in RollingFileAppenderSkeleton.

virtual void writeFooter | ( | log4cxx::helpers::Pool & | p | ) | `[protected, virtual]`

| Write a footer as produced by the embedded layout's Layout::appendFooter method.

virtual void writeHeader | ( | log4cxx::helpers::Pool & | p | ) | `[protected, virtual]`

| Write a header as produced by the embedded layout's Layout::appendHeader method.

The documentation for this class was generated from the following file:

- writerappender.h