Package java.util.logging

Class MemoryHandler

java.lang.Object

java.util.logging.Handler

java.util.logging.MemoryHandler

public class MemoryHandler
extends Handler

A Handler put the description of log events into a cycled memory buffer.

Mostly this MemoryHandler just puts the given LogRecord into the internal buffer and doesn't perform any formatting or any other process. When the buffer is full, the earliest buffered records will be discarded.

Every MemoryHandler has a target handler, and push action can be triggered so that all buffered records will be output to the target handler and normally the latter will publish the records. After the push action, the buffer will be cleared.

The push method can be called directly, but will also be called automatically if a new LogRecord is added that has a level greater than or equal to than the value defined for the property java.util.logging.MemoryHandler.push.

MemoryHandler will read following LogManager properties for initialization, if given properties are not defined or has invalid values, default value will be used.

• java.util.logging.MemoryHandler.filter specifies the Filter class name, defaults to no Filter.
• java.util.logging.MemoryHandler.level specifies the level for this Handler, defaults to Level.ALL.
• java.util.logging.MemoryHandler.push specifies the push level, defaults to level.SEVERE.
• java.util.logging.MemoryHandler.size specifies the buffer size in number of LogRecord, defaults to 1000.
• java.util.logging.MemoryHandler.target specifies the class of the target Handler, no default value, which means this property must be specified either by property setting or by constructor.

Constructor Summary

Constructors

Constructor	Description
MemoryHandler()	Default constructor, construct and init a MemoryHandler using LogManager properties or default values.
MemoryHandler(Handler target, int size, Level pushLevel)	Construct and init a MemoryHandler using given target, size and push level, other properties using LogManager properties or default values.

Method Summary

Modifier and Type	Method	Description
void	close()	Close this handler and target handler, free all associated resources.
void	flush()	Call target handler to flush any buffered output.
Level	getPushLevel()	Return the push level.
boolean	isLoggable(LogRecord record)	Check if given LogRecord would be put into this MemoryHandler's internal buffer.
void	publish(LogRecord record)	Put a given LogRecord into internal buffer.
void	push()	Triggers a push action to output all buffered records to the target handler, and the target handler will publish them.
void	setPushLevel(Level newLevel)	Set the push level.

Methods inherited from class java.util.logging.Handler

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

Methods inherited from class java.lang.Object

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

Constructor Details

MemoryHandler

public MemoryHandler()

Default constructor, construct and init a MemoryHandler using LogManager properties or default values.

Throws:

RuntimeException - if property value are invalid and no default value could be used.

MemoryHandler

public MemoryHandler(Handler target,
int size,
Level pushLevel)

Construct and init a MemoryHandler using given target, size and push level, other properties using LogManager properties or default values.

Parameters:

target - the given Handler to output

size - the maximum number of buffered LogRecord, greater than zero

pushLevel - the push level

Throws:

IllegalArgumentException - if size <= 0

RuntimeException - if property value are invalid and no default value could be used.

Method Details

close

public void close()

Close this handler and target handler, free all associated resources.

Specified by:

close in class Handler

flush

public void flush()

Call target handler to flush any buffered output. Note that this doesn't cause this MemoryHandler to push.

Specified by:

flush in class Handler

publish

public void publish(LogRecord record)

Put a given LogRecord into internal buffer. If given record is not loggable, just return. Otherwise it is stored in the buffer. Furthermore if the record's level is not less than the push level, the push action is triggered to output all the buffered records to the target handler, and the target handler will publish them.

Specified by:

publish in class Handler

Parameters:

record - the log record

getPushLevel

public Level getPushLevel()

Return the push level.

Returns:

the push level

isLoggable

public boolean isLoggable(LogRecord record)

Check if given LogRecord would be put into this MemoryHandler's internal buffer.

The given LogRecord is loggable if and only if it has appropriate level and it pass any associated filter's check.

Note that the push level is not used for this check.

Overrides:

isLoggable in class Handler

Parameters:

record - the given LogRecord

Returns:

the given LogRecord if it should be logged, false if LogRecord is null.

push

public void push()

Triggers a push action to output all buffered records to the target handler, and the target handler will publish them. Then the buffer is cleared.

setPushLevel

public void setPushLevel(Level newLevel)

Set the push level. The push level is used to check the push action triggering. When a new LogRecord is put into the internal buffer and its level is not less than the push level, the push action will be triggered. Note that set new push level won't trigger push action.

Parameters:

newLevel - the new level to set.