public class

MemoryHandler

extends Handler
java.lang.Object
   ↳ java.util.logging.Handler
     ↳ java.util.logging.MemoryHandler

Class Overview

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.

Summary

Public Constructors
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.
Public Methods
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.
synchronized 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.
[Expand]
Inherited Methods
From class java.util.logging.Handler
From class java.lang.Object

Public Constructors

public MemoryHandler ()

Since: API Level 1

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.

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

Since: API Level 1

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.

Public Methods

public void close ()

Since: API Level 1

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

Throws
SecurityException if security manager exists and it determines that caller does not have the required permissions to control this handler.

public void flush ()

Since: API Level 1

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

public Level getPushLevel ()

Since: API Level 1

Return the push level.

Returns
  • the push level

public boolean isLoggable (LogRecord record)

Since: API Level 1

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.

Parameters
record the given LogRecord
Returns
  • the given LogRecord if it should be logged, false if LogRecord is null.

public synchronized void publish (LogRecord record)

Since: API Level 1

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.

Parameters
record the log record

public void push ()

Since: API Level 1

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.

public void setPushLevel (Level newLevel)

Since: API Level 1

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.
Throws
SecurityException if security manager exists and it determines that caller does not have the required permissions to control this handler.