将logger中的 additivity 属性配置为 false，则这个logger不会将日志流反馈到root中。
可以达到以logger中配置的appender方式来输出日志而其他地方输出的目的，看配置：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 < appender name = "DEMO" class = "com.XXXXX.RollingFileAppender" > < param name = "file" value = "${loggingRoot}/xxx.log" /> < param name = "append" value = "true" /> < param name = "encoding" value = "GB2312" /> < param name = "threshold" value = "info" /> < param name = "MaxFileSize" value = "50MB" /> < param name = "MaxBackupIndex" value = "10" /> < layout class = "org.apache.log4j.PatternLayout" > < param name = "ConversionPattern" value = "%d [%X{requestURIWithQueryString}] %-5p %c{2} - %m%n" /> </ layout > </ appender > < logger name = "XXXX.XXXX.XXXX" additivity = "false" > < level value = "${loggingLevel}" /> < appender-ref ref = "DEMO" /> </ logger >root的作用是收集下面所有反馈上来的信息流并根据配置在root中appender进行输出，只要你在looger中配置了additivity="false"，就不会反馈到root中。
意味着不会重复输出！