log4j WARN No appenders could be found for logger解决方法

在maven工程里面使用log4j报如下警告：

log4j:WARN No appenders could be found for logger (com.appium.framework.automation.util.TestLog).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

需要把log4j.properties配置文件放在source目录下，会自动拷贝到class下。