Class MemoryHandler
- java.lang.Object
-
- java.util.logging.Handler
-
- java.util.logging.MemoryHandler
public class MemoryHandler extends Handler
Handler
that buffers requests in a circular buffer in memory.
Normally this Handler
simply stores incoming LogRecords
into its memory buffer and discards earlier records. This buffering is very cheap and avoids formatting costs. On certain trigger conditions, the MemoryHandler
will push out its current buffer contents to a target Handler
, which will typically publish them to the outside world.
There are three main models for triggering a push of the buffer:
- An incoming
LogRecord
has a type that is greater than a pre-defined level, thepushLevel
. - An external class calls the
push
method explicitly. - A subclass overrides the
log
method and scans each incomingLogRecord
and callspush
if a record matches some desired criteria.
Configuration: By default each MemoryHandler
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. If no default value is defined then a RuntimeException is thrown.
- <handler-name>.level specifies the level for the
Handler
(defaults toLevel.ALL
). - <handler-name>.filter specifies the name of a
Filter
class to use (defaults to noFilter
). - <handler-name>.size defines the buffer size (defaults to 1000).
- <handler-name>.push defines the
pushLevel
(defaults tolevel.SEVERE
). - <handler-name>.target specifies the name of the target
Handler
class. (no default).
For example, the properties for MemoryHandler
would be:
- java.util.logging.MemoryHandler.level=INFO
- java.util.logging.MemoryHandler.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
Constructor | Description |
---|---|
MemoryHandler() | Create a |
MemoryHandler(Handler target,
int size,
Level pushLevel) | Create a |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | close() | Close the |
void | flush() | Causes a flush on the target |
Level | getPushLevel() | Get the |
boolean | isLoggable(LogRecord record) | Check if this |
void | publish(LogRecord record) | Store a |
void | push() | Push any buffered output to the target |
void | setPushLevel(Level newLevel) | Set the |
Methods declared in class java.util.logging.Handler
getEncoding, getErrorManager, getFilter, getFormatter, getLevel, reportError, setEncoding, setErrorManager, setFilter, setFormatter, setLevel
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
MemoryHandler
public MemoryHandler()
Create a MemoryHandler
and configure it based on LogManager
configuration properties.
MemoryHandler
public MemoryHandler(Handler target, int size, Level pushLevel)
Create a MemoryHandler
.
The MemoryHandler
is configured based on LogManager
properties (or their default values) except that the given pushLevel
argument and buffer size argument are used.
- Parameters:
-
target
- the Handler to which to publish output. -
size
- the number of log records to buffer (must be greater than zero) -
pushLevel
- message level to push on - Throws:
-
IllegalArgumentException
- ifsize is <= 0
Method Detail
publish
public void publish(LogRecord record)
Store a LogRecord
in an internal buffer.
If there is a Filter
, its isLoggable
method is called to check if the given log record is loggable. If not we return. Otherwise the given record is copied into an internal circular buffer. Then the record's level property is compared with the pushLevel
. If the given level is greater than or equal to the pushLevel
then push
is called to write all buffered records to the target output Handler
.
- Specified by:
-
publish
in classHandler
- Parameters:
-
record
- description of the log event. A null record is silently ignored and is not published
push
public void push()
Push any buffered output to the target Handler
.
The buffer is then cleared.
flush
public void flush()
Causes a flush on the target Handler
.
Note that the current contents of the MemoryHandler
buffer are not written out. That requires a "push".
close
public void close() throws SecurityException
Close the Handler
and free all associated resources. This will also close the target Handler
.
- Specified by:
-
close
in classHandler
- Throws:
-
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
.
setPushLevel
public void setPushLevel(Level newLevel) throws SecurityException
Set the pushLevel
. After a LogRecord
is copied into our internal buffer, if its level is greater than or equal to the pushLevel
, then push
will be called.
- Parameters:
-
newLevel
- the new value of thepushLevel
- Throws:
-
SecurityException
- if a security manager exists and if the caller does not haveLoggingPermission("control")
.
getPushLevel
public Level getPushLevel()
Get the pushLevel
.
- Returns:
- the value of the
pushLevel
isLoggable
public boolean isLoggable(LogRecord record)
Check if this Handler
would actually log a given LogRecord
into its internal buffer.
This method checks if the LogRecord
has an appropriate level and whether it satisfies any Filter
. However it does not check whether the LogRecord
would result in a "push" of the buffer contents. It will return false if the LogRecord
is null.
- Overrides:
-
isLoggable
in classHandler
- Parameters:
-
record
- aLogRecord
(may be null). - Returns:
- true if the
LogRecord
would be logged.