Log4j 面试题与答案

问题 21. How will you define a root logger turning DEBUG mode off?

The following syntax defines the root logger with WARN mode turning DEBUG mode off.

# Define the root logger with appender file

log = /usr/home/log4j log4j.rootLogger = WARN, FILE

问题 22. What are the other support objects in Log4j?

There are other support objects in the Log4j framework are:

• Level Object
• Filter Object
• Object Renderer
• Log Manager

问题 23. In log4j how can you log into the database?

The log4j API provides the object org.apache.log4j.jdbc. JDBCAppender object can put logging information in a particular database.

问题 24. Explain whether log4j is a thread safe.

Log4j is a thread-safe, log4j components are built to be used in multithread systems.

问题 25. Explain whether a log output format can be customized.

Yes, you can extend the layout class to create your own customized log format. Appenders can be parameterized to use the layout of your choice.