logback如何发现configuration file

今天发现日志一直打印debug没有加载configuration file中配置的格式，通过debug找到logback记载配置的流程。

当调用

org.slf4j.LoggerFactory.getLogger(StandaloneLoggingModule.class)

的调用过程如下：

--->LoggerFactory.getLogger(Class clazz)
	--->iLoggerFactory=slf4j.LoggerFactory.getILoggerFactory()
		--->slf4j.LoggerFactory.performInitialization()
			--->slf4j.LoggerFactory.bind()
				--->org.slf4j.impl.StaticLoggerBinder.getSingleton()
					--->org.slf4j.impl.StaticLoggerBinder.init()
						--->new ch.qos.logback.classic.util.ContextInitializer(defaultLoggerContext).autoConfig()
	--->iLoggerFactory.getLogger(name)

ch.qos.logback.classic.util.ContextInitializer.autoConfig()执行过程

--->ContextInitializer.findURLOfDefaultConfigurationFile(true)
--->ContextInitializer.findConfigFileURLFromSystemProperties(myClassLoader, updateStatus);
---> String logbackConfigFile =OptionHelper.getSystemProperty("logback.configurationFile");
---> URL  result = new URL(logbackConfigFile);
---> 如果出现MalformedURLException, result = Loader.getResource(logbackConfigFile, classLoader)
--> ContextInitializer.configureByResource(url)