slf4j

slf4j与log4j的区别：

http://stackoverflow.com/questions/4516932/difference-between-slf4j-and-log4j

下面是slf4j的入门手册：

http://www.slf4j.org/manual.html

the first baby step with slf4j and logback. ,slf4j和logback原生就结合在一起

http://logback.qos.ch/manual/introduction.html

关于如何放置配置文件，有一点需要注意：

Configuration files such as logback.groovy, logback-test.xml or logback.xml can be located directly under any folder declared in the class path. For example, if the class path reads "c:/java/jdk15/lib/rt.jar;c:/mylibs/" then the logback.xml file should be located directly under "c:/mylibs/", that is as "c:/mylibs/logback.xml". Placing it under a sub-folder of c:/mylibs/, say, c:/mylibs/other/, will not work.

For web-applications, configuration files can be placed directly under WEB-INF/classes/.