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:
LogRecord has a type that is greater than a pre-defined level, the pushLevel. push method explicitly. log method and scans each incoming LogRecord and calls push 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 (defaults to Level.ALL). Filter class to use (defaults to no Filter). pushLevel (defaults to level.SEVERE). Handler class. (no default). For example, the properties for MemoryHandler would be:
For a custom handler, e.g. com.foo.MyHandler, the properties would be:
public MemoryHandler()
Create a MemoryHandler and configure it based on LogManager configuration properties.
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.
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 onIllegalArgumentException - if size is <= 0
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.
publish in class Handler
record - description of the log event. A null record is silently ignored and is not publishedpublic void push()
Push any buffered output to the target Handler.
The buffer is then cleared.
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".
public void close()
throws SecurityException Close the Handler and free all associated resources. This will also close the target Handler.
close in class Handler
SecurityException - if a security manager exists and if the caller does not have LoggingPermission("control").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.
newLevel - the new value of the pushLevel
SecurityException - if a security manager exists and if the caller does not have LoggingPermission("control").public Level getPushLevel()
Get the pushLevel.
pushLevel
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.
isLoggable in class Handler
record - a LogRecord
LogRecord would be logged.
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