public class WriterAppender extends AppenderSkeleton
Writer or an
OutputStream depending on the user's choice.| 限定符和类型 | 字段和说明 |
|---|---|
protected java.lang.String |
encoding
The encoding to use when writing.
|
protected boolean |
immediateFlush
Immediate flush means that the underlying writer or output stream
will be flushed at the end of each append operation unless shouldFlush()
is overridden.
|
protected QuietWriter |
qw
This is the
quietWriter where we will write
to. |
closed, errorHandler, headFilter, layout, name, tailFilter, threshold| 构造器和说明 |
|---|
WriterAppender()
This default constructor does nothing.
|
WriterAppender(Layout layout,
java.io.OutputStream os)
Instantiate a WriterAppender and set the output destination to a
new
OutputStreamWriter initialized with os
as its OutputStream. |
WriterAppender(Layout layout,
java.io.Writer writer)
Instantiate a WriterAppender and set the output destination to
writer. |
| 限定符和类型 | 方法和说明 |
|---|---|
void |
activateOptions()
Does nothing.
|
void |
append(LoggingEvent event)
This method is called by the
AppenderSkeleton.doAppend(com.fr.third.apache.log4j.spi.LoggingEvent)
method. |
protected boolean |
checkEntryConditions()
This method determines if there is a sense in attempting to append.
|
void |
close()
Close this appender instance.
|
protected void |
closeWriter()
Close the underlying
Writer. |
protected java.io.OutputStreamWriter |
createWriter(java.io.OutputStream os)
Returns an OutputStreamWriter when passed an OutputStream.
|
java.lang.String |
getEncoding() |
boolean |
getImmediateFlush()
Returns value of the ImmediateFlush option.
|
boolean |
requiresLayout()
The WriterAppender requires a layout.
|
protected void |
reset()
Clear internal references to the writer and other variables.
|
void |
setEncoding(java.lang.String value) |
void |
setErrorHandler(ErrorHandler eh)
Set the
ErrorHandler for this WriterAppender and also the
underlying QuietWriter if any. |
void |
setImmediateFlush(boolean value)
If the ImmediateFlush option is set to
true, the appender will flush at the end of each
write. |
void |
setWriter(java.io.Writer writer)
Sets the Writer where the log output will go.
|
protected boolean |
shouldFlush(LoggingEvent event)
Determines whether the writer should be flushed after
this event is written.
|
protected void |
subAppend(LoggingEvent event)
Actual writing occurs here.
|
protected void |
writeFooter()
Write a footer as produced by the embedded layout's
Layout.getFooter() method. |
protected void |
writeHeader()
Write a header as produced by the embedded layout's
Layout.getHeader() method. |
addFilter, clearFilters, doAppend, finalize, getErrorHandler, getFilter, getFirstFilter, getLayout, getName, getThreshold, isAsSevereAsThreshold, setLayout, setName, setThresholdprotected boolean immediateFlush
immediateFlush is set to
false, then there is a good chance that the last few
logs events are not actually written to persistent media if and
when the application crashes.
The immediateFlush variable is set to
true by default.
protected java.lang.String encoding
The
encoding variable is set to null by
default which results in the utilization of the system's default
encoding.
protected QuietWriter qw
quietWriter where we will write
to.public WriterAppender()
public WriterAppender(Layout layout, java.io.OutputStream os)
OutputStreamWriter initialized with os
as its OutputStream.public WriterAppender(Layout layout, java.io.Writer writer)
writer.
The writer must have been previously opened by
the user.
public void setImmediateFlush(boolean value)
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.
public boolean getImmediateFlush()
public void activateOptions()
activateOptions 在接口中 OptionHandleractivateOptions 在类中 AppenderSkeletonpublic void append(LoggingEvent event)
AppenderSkeleton.doAppend(com.fr.third.apache.log4j.spi.LoggingEvent)
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 System.err.
The format of the output will depend on this appender's layout.
append 在类中 AppenderSkeletonprotected boolean checkEntryConditions()
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.
public void close()
Closed appenders cannot be reused.
setWriter(java.io.Writer)protected void closeWriter()
Writer.protected java.io.OutputStreamWriter createWriter(java.io.OutputStream os)
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.public java.lang.String getEncoding()
public void setEncoding(java.lang.String value)
public void setErrorHandler(ErrorHandler eh)
ErrorHandler for this WriterAppender and also the
underlying QuietWriter if any.setErrorHandler 在接口中 AppendersetErrorHandler 在类中 AppenderSkeletonpublic void setWriter(java.io.Writer 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.
writer - An already opened Writer.protected void subAppend(LoggingEvent event)
Most subclasses of WriterAppender will need to
override this method.
public boolean requiresLayout()
true.protected void reset()
protected void writeFooter()
Layout.getFooter() method.protected void writeHeader()
Layout.getHeader() method.protected boolean shouldFlush(LoggingEvent event)