Introduction to logback appender

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logback appender Introduction

The following is about logback Of appender Introduction to , As shown below :

logback in appender It's the component responsible for writing logs 
 appender The function of : Used to set the destination of log output 
    The location of log output can be console 、 file 、 Remote socket server 、MySQL And other databases 、JMS And remote UNIX Syslog Daemons, etc 

appender type

ConsoleAppender: Print the log to the console 
FileAppender: Output the log to a file 
RollingFileAppender: Output the log to a file by rolling records , That is, the log file can be split by file size or by date 

example

<appender name="infoAppender" class="ch.qos.logback.core.rolling.RollingFileAppender">
	<!--  File path  -->
	<file>${log.filePath}/info.log</file>
	<!--  Rolling strategy  -->
	<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
		<!--  Set file name  -->
		<fileNamePattern>
			${log.filePath}/info/info.%d{yyyy-MM-dd}.log.gz
		</fileNamePattern>
		<!--  Set the maximum save cycle  -->
		<MaxHistory>${log.maxHistory}</MaxHistory>
	</rollingPolicy>
	<encoder>
		<pattern>${log.pattern}</pattern>
	</encoder>
	<!--  filter , Filter out logs that are not at the specified log level  -->
	<filter class="ch.qos.logback.classic.filter.LevelFilter">
		<!--  Set the log level  -->
		<level>INFO</level>
		<!--  If it matches the log level , received  -->
		<onMatch>ACCEPT</onMatch>
		<!--  If it does not match the log level , Filter out  -->
		<onMismatch>DENY</onMismatch>
	</filter>
</appender>

logback Child node

filter filter

LevelFilter: Grade filter , Filter by log level . If the log level is equal to the configuration level , The filter will be based on onMath  and  onMismatch Receive or reject logs 
ThresholdFilter: Threshold filter , Filter out logs below the specified threshold . When the log level is equal to or higher than the threshold , Filter return NEUTRAL; When the log level is below the threshold , Logs will be rejected 
EvaluatorFilter: Evaluation filters , assessment 、 Identify whether the log meets the specified conditions 

rollingPolicy

Used to set the rolling strategy of logs
When the condition is met, the log before the condition will be automatically generated into a backup log file
The log after the condition is output to the latest log file
Commonly used is to scroll by time ( Classes used TimeBaseRollingPolicy)
Another is to implement based on index ( Classes used FixedWindowRollingPolicy)

fileNamePattern Property to set the format of the rolling generation file , The setting here is accurate to days , That is, roll by day , If the time setting is accurate to seconds , Just scroll by seconds

maxHistory Property to set the maximum number of files , For example, scroll by day , I've set it up here 30 God , In the 31 When the daily log is generated , The log of the first day will be deleted

triggeringPolicy

Log trigger policy , Used to set the size of the log
When the log reaches the corresponding size , It will trigger
Generate a new log file . Log size control coordination rollingPlicy When you use it , Different rollingPolicy It will be different

encoder

encoder Property is used to convert the event into a byte array and write the byte array to the appropriate output stream
encoder Attribute values can be specified class, There is only one corresponding class PatternLayoutEncoder, It's also the default value , You don't have to specify