LogManager在初始化的过程中,读取log4j.configuration系统变量的值,生成配置文件的url,默认为log4j.properties或log4j.xml.然后用PropertyConfigurator类来解析log4j.properties文件.
读源码才明白,PropertyConfigurator类实现了Configurator接口,重载了configure方法来读取properties文件,然后又通过重载doConfigure方法来装配logger的属性.
具体的源码请参看log4j/logging-log4j-1.2.13/src/java/org/apache/log4j/PropertyConfigurator.java.
而对于log4j.xml文件则是通过DOMConfigurator.java类来解析的.
具体的源码参看log4j/logging-log4j-1.2.13/src/java/org/apache/log4j/xml/DOMConfigurator.java