Log4j 面试题与答案

Question: What are the features of log4j?

The following are features of log4j:

• Log4j is thread-safe.
• It is optimized for speed.
• It is based on a named logger hierarchy.
• It supports multiple output appenders per logger.
• It supports internationalization.
• It is not restricted to a predefined set of facilities.
• Logging behavior can be set at runtime using a configuration file.
• It is designed to handle Java Exceptions from the start.
• It uses multiple levels, namely ALL, TRACE, DEBUG, INFO, WARN, ERROR, and FATAL.
• The format of the log output can be easily changed by extending the Layout class.
• The target of the log output as well as the writing strategy can be altered by implementations of the Appender interface.
• It is a fail-stop. However, although it certainly strives to ensure delivery, log4j does not guarantee that each log statement will be delivered to its destination.