Class StreamHandler

java.lang.Object

java.util.logging.Handler

java.util.logging.StreamHandler

Direct Known Subclasses:

ConsoleHandler, FileHandler, SocketHandler

public class StreamHandler
extends Handler

Stream based logging Handler.

This is primarily intended as a base class or support class to be used in implementing other logging Handlers.

LogRecords are published to a given java.io.OutputStream.

Configuration: By default each StreamHandler is initialized using the following LogManager configuration properties where <handler-name> refers to the fully-qualified class name of the handler. If properties are not defined (or have invalid values) then the specified default values are used.

• <handler-name>.level specifies the default level for the Handler (defaults to Level.INFO).
• <handler-name>.filter specifies the name of a Filter class to use (defaults to no Filter).
• <handler-name>.formatter specifies the name of a Formatter class to use (defaults to java.util.logging.SimpleFormatter).
• <handler-name>.encoding the name of the character set encoding to use (defaults to the default platform encoding).

For example, the properties for StreamHandler would be:

• java.util.logging.StreamHandler.level=INFO
• java.util.logging.StreamHandler.formatter=java.util.logging.SimpleFormatter

For a custom handler, e.g. com.foo.MyHandler, the properties would be:

• com.foo.MyHandler.level=INFO
• com.foo.MyHandler.formatter=java.util.logging.SimpleFormatter

Since:

1.4

Constructor Summary

Constructors

Constructor	Description
StreamHandler()	Create a StreamHandler, with no current output stream.
StreamHandler(OutputStream out, Formatter formatter)	Create a StreamHandler with a given Formatter and output stream.

Method Summary

Modifier and Type	Method	Description
void	close()	Close the current output stream.
void	flush()	Flush any buffered messages.
boolean	isLoggable(LogRecord record)	Check if this Handler would actually log a given LogRecord.
void	publish(LogRecord record)	Format and publish a LogRecord.
void	setEncoding(String encoding)	Set (or change) the character encoding used by this Handler.
protected void	setOutputStream(OutputStream out)	Change the output stream.

Methods declared in class Handler

getEncoding, getErrorManager, getFilter, getFormatter, getLevel, reportError, setErrorManager, setFilter, setFormatter, setLevel

Modifier and Type	Method	Description
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.
Level	getLevel()	Get the log level specifying which messages will be logged by this Handler.
protected void	reportError(String msg, Exception ex, int code)	Protected convenience method to report an error to this Handler's ErrorManager.
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.
void	setLevel(Level newLevel)	Set the log level specifying which message levels will be logged by this Handler.

Methods declared in class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Constructor Details

StreamHandler

public StreamHandler()

Create a StreamHandler, with no current output stream.

StreamHandler

public StreamHandler(OutputStream out,
 Formatter formatter)

Create a StreamHandler with a given Formatter and output stream.

Parameters:

out - the target output stream

formatter - Formatter to be used to format output

Method Details

setOutputStream

protected void setOutputStream(OutputStream out)

Change the output stream.

If there is a current output stream then the Formatter's tail string is written and the stream is flushed and closed. Then the output stream is replaced with the new output stream.

Parameters:

out - New output stream. May not be null.

setEncoding

public void setEncoding(String encoding)
                 throws UnsupportedEncodingException

Set (or change) the character encoding used by this Handler.

The encoding should be set before any LogRecords are written to the Handler.

Overrides:

setEncoding in class Handler

Parameters:

encoding - The name of a supported character encoding. May be null, to indicate the default platform encoding.

Throws:

UnsupportedEncodingException - if the named encoding is not supported.

publish

public void publish(LogRecord record)

Format and publish a LogRecord.

The StreamHandler first checks if there is an OutputStream and if the given LogRecord has at least the required log level. If not it silently returns. If so, it calls any associated Filter to check if the record should be published. If so, it calls its Formatter to format the record and then writes the result to the current output stream.

If this is the first LogRecord to be written to a given OutputStream, the Formatter's "head" string is written to the stream before the LogRecord is written.

Specified by:

publish in class Handler

Implementation Requirements:

This method avoids acquiring locks during LogRecord formatting, but this instance is synchronized when writing to the output stream. To avoid deadlock risk, subclasses must not hold locks while calling super.publish(). Specifically, subclasses must not define the overridden publish() method to be synchronized if they call super.publish().

Parameters:

record - description of the log event. A null record is silently ignored and is not published

isLoggable

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 will also return false if no output stream has been assigned yet or the LogRecord is null.

Overrides:

isLoggable in class Handler

Parameters:

record - a LogRecord (may be null).

Returns:

true if the LogRecord would be logged.

flush

public void flush()

Flush any buffered messages.

Specified by:

flush in class Handler

close

public void close()

Close the current output stream.

The Formatter's "tail" string is written to the stream before it is closed. In addition, if the Formatter's "head" string has not yet been written to the stream, it will be written before the "tail" string.

Specified by:

close in class Handler