添加maven依赖后，不报错：

<!--slf4j-->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-nop</artifactId>
            <version>1.7.25</version>
        </dependency>

上述操作并没有添加 log4j.properties，但是添加之后，也不打印日志

log.path=/Users/walker/tmp/log4j/

### direct log messages to stdout ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %C{1}:%L - %m%n

### direct messages to file mylog.log ###
log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=${log.path}/mylog.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %C{1}:%L - %m%n

### set log levels - for more verbose logging change 'info' to 'debug' ###
log4j.rootLogger=debug,stdout

 

上述操作并没有在代码中 添加日志输出相关的代码