Today finally finished reading the log4j, the mood is good! Take out your own study notes and share them with us.

Note 1.log4j has three main components: logger, Appender and Layout2. LOG4J offers the following appender: Org.apache.log4j.ConsoleAppender (console) org.apache.log4j.FileAppender (file) Org.apache.log4j.DailyRollingFileAppender (generates a log file every day) Org.apache.log4j.RollingFileAppender (a new file is generated when the file size reaches a specified size) Org.apach E.log4j.writerappender (sending log information in streaming format to any specified place) 3.log4j provides the following layout: Org.apache.log4j.HTMLLayout (layout in HTML tabular form) Org.apache.log4j.PatternLayout (the flexibility to specify layout patterns) Org.apache.log4j.SimpleLayout (the level and information string that contains the log information) Org.apache.log4j.TTCCLayout (contains log Time, thread, category, etc information) 4. LOG4J provides several output formats:%m:used to output the method name where the logging request is issued.%m:used to output the application Su Pplied message associated with the logging event.%l:used to output location information of the caller which the Logging event%l:used to output the line number from where the logging request is issued.%p:used to output the priority of The logging event.%n:outputs the platform dependent line separator character or characters. %r:used to output the Nu Mber ofMilliseconds elapsed since the start of the application until creation of the logging to output the file Name where the logging request is issued.%d:used to output the date of the logging event. %c:used to output the cat Egory of the logging event%c:used to output the fully qualified class name of the caller issuing the logging. If the In the case of high efficiency requirements, the Log.debug () before the log.isdebugenabled () to judge, which can greatly reduce the execution time 6. For each appenders, Common properties are layout (typically set to Org.apache.log4j.PatternLayout), Threshold (log level) (1) Consoleappender:target ( System.out and System.err) (2) Fileappender:file (defines the file name of the output), Append (defined as append) ( 3 Dailyrollingfileappender (except Fileappender attribute): maxfilesize (maximum file size), Maxbackupindex ()


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