log4j:WARN No appenders could be found for logger

在測試JSEL時，調用自定義函數時，出現 異常以下：

log4j:WARN No appenders could be found for logger

log4j:WARN Please initialize the log4j system properly.

解決辦法 參考Joshua Taylor的回答 ，連接以下：

http://stackoverflow.com/questions/12532339/no-appenders-could-be-found-for-loggerlog4j

內容以下：

This Short introduction to log4j guide is a little bit old but still valid.

That guide will give you some information about how to use loggers and appenders.

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Just to get you going you have two simple approaches you can take.

First one is to just add this line to your main method:

BasicConfigurator.configure();

Second approach is to add this standard log4j.properties (taken from the above mentioned guide) file to your classpath:

# Set root logger level to DEBUG and its only appender to A1.log4j.rootLogger=DEBUG, A1# A1 is set to be a ConsoleAppender.log4j.appender.A1=org.apache.log4j.ConsoleAppender# A1 uses PatternLayout.log4j.appender.A1.layout=org.apache.log4j.PatternLayoutlog4j.appender.A1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n