Package org.apache.sis.util.logging

Class LoggerFactory<L>

  • Type Parameters:
    L - the type of loggers used for the implementation backend. This is the type used by external frameworks like Log4J.
    public abstract class LoggerFactory<L>
extends Object
    A factory for Java Logger wrapping an other logging framework. This factory is used only when an application wants to redirect SIS logs to an other framework than JDK logging. An instance of Logger­Factory can be registered to SIS in two ways:
    • By declaring the fully qualified classname of the Logger­Factory implementation in the META-INF/services/org​.apache​.sis​.util​.logging​.Logger­Factory file. Note that the sis-logging-commons​.jar and sis-logging-log4j​.jar files provide such declaration.
    • By explicit invocation of Logging​.set­Logger­Factory(Logger­Factory) at application initialization time.
    The get­Logger(String) method shall return some Logger subclass (typically Logger­Adapter) which forwards directly all log methods to the other framework.
    Thread safety
    This base class is safe for multi-threads usage. Subclasses registered in META-INF/services/ shall make sure that any overridden methods remain safe to call from multiple threads.
    Since:
    0.3
    See Also:
    Logging, Logger­Adapter

    Defined in the sis-utility module

    • Constructor Detail

      • LoggerFactory

        protected LoggerFactory​(Class<L> loggerClass)
        Creates a new factory.
        Parameters:
        logger­Class - The class of the wrapped logger.

    • Method Detail

      • getName

        public abstract String getName()
        Returns the name of the logging framework.
        Returns:
        the logging framework name.

      • getLogger

        public Logger getLogger​(String name)
        Returns the logger of the specified name, or null if the JDK logging framework should be used.
        Parameters:
        name - the name of the logger.
        Returns:
        the logger, or null if the JDK logging framework should be used.

      • getImplementationClass

        public Class<L> getImplementationClass()
        Returns the base class of objects to be returned by get­Implementation(String). The class depends on the underlying logging framework (Log4J, SLF4J, etc.).
        Returns:
        the type of loggers used for the implementation backend.

      • getImplementation

        protected abstract L getImplementation​(String name)
        Returns the implementation to use for the logger of the specified name. The object to be returned depends on the logging framework (Log4J, SLF4J, etc.). If the target framework redirects logging events to JDK logging, then this method shall return null since we should not use wrapper at all.
        Parameters:
        name - the name of the logger.
        Returns:
        the logger as an object of the target logging framework (Log4J, SLF4J, etc.), or null if the target framework would redirect to the JDK logging framework.

      • wrap

        protected abstract Logger wrap​(String name,
                               L implementation)
        Wraps the specified implementation in a JDK logger.
        Parameters:
        name - the name of the logger.
        implementation - an implementation returned by get­Implementation(String).
        Returns:
        a new logger wrapping the specified implementation.

      • unwrap

        protected abstract L unwrap​(Logger logger)
        Returns the implementation wrapped by the specified logger, or null if none. If the specified logger is not an instance of the expected class, then this method should returns null.
        Parameters:
        logger - the logger to test.
        Returns:
        the implementation wrapped by the specified logger, or null if none.