org.apache.log4j.spi
public abstract class Filter extends Object implements OptionHandler
This abstract class assumes and also imposes that filters be organized in a linear chain. The {@link #decide decide(LoggingEvent)} method of each filter is called sequentially, in the order of their addition to the chain.
The {@link #decide decide(LoggingEvent)} method must return one of the integer constants {@link #DENY}, {@link #NEUTRAL} or {@link #ACCEPT}.
If the value {@link #DENY} is returned, then the log event is dropped immediately without consulting with the remaining filters.
If the value {@link #NEUTRAL} is returned, then the next filter in the chain is consulted. If there are no more filters in the chain, then the log event is logged. Thus, in the presence of no filters, the default behaviour is to log all logging events.
If the value {@link #ACCEPT} is returned, then the log event is logged without consulting the remaining filters.
The philosophy of log4j filters is largely inspired from the Linux ipchains.
Note that filtering is only supported by the {@link org.apache.log4j.xml.DOMConfigurator DOMConfigurator}. The {@link org.apache.log4j.PropertyConfigurator PropertyConfigurator} does not support filters.
Since: 0.9.0
Field Summary | |
---|---|
static int | ACCEPT
The log event must be logged immediately without consulting with
the remaining filters, if any, in the chain. |
static int | DENY
The log event must be dropped immediately without consulting
with the remaining filters, if any, in the chain. |
Filter | next
Points to the next filter in the filter chain. |
static int | NEUTRAL
This filter is neutral with respect to the log event. |
Method Summary | |
---|---|
void | activateOptions()
Usually filters options become active when set. |
abstract int | decide(LoggingEvent event) If the decision is |
Filter | getNext()
Return the pointer to the next filter; |
void | setNext(Filter next)
Set the next filter pointer. |
Deprecated: As of 1.2.12, use {@link #getNext} and {@link #setNext} instead
Points to the next filter in the filter chain.If the decision is DENY
, then the event will be
dropped. If the decision is NEUTRAL
, then the next
filter, if any, will be invoked. If the decision is ACCEPT then
the event will be logged without consulting with other filters in
the chain.
Parameters: event The LoggingEvent to decide upon.
Returns: decision The decision of the filter.