引入jar包

<!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-log4j12 -->
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-log4j12</artifactId>
    <version>1.7.30</version>
</dependency>

log4j.properties

### 设置 ###
log4j.rootLogger = debug, stdout, D, I, W, E

### 输出信息到控制台 ###
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{yyyy-MM-dd HH:mm:ss,SSS}] [ %t:%r ] %5p %l - %m%n

### 输出DEBUG级别以上的日志到logs/debug.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = logs/debug.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = DEBUG
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = [%d{yyyy-MM-dd HH:mm:ss,SSS}] [ %t:%r ] %5p %l - %m%n

### 输出INFO级别以上的日志到logs/info.log ###
log4j.appender.I = org.apache.log4j.DailyRollingFileAppender
log4j.appender.I.File = logs/info.log
log4j.appender.I.Append = true
log4j.appender.I.Threshold = INFO
log4j.appender.I.layout = org.apache.log4j.PatternLayout
log4j.appender.I.layout.ConversionPattern = [%d{yyyy-MM-dd HH:mm:ss,SSS}] [ %t:%r ] %5p %l - %m%n

### 输出WARN级别以上的日志到logs/warn.log ###
log4j.appender.W = org.apache.log4j.DailyRollingFileAppender
log4j.appender.W.File = logs/warn.log
log4j.appender.W.Append = true
log4j.appender.W.Threshold = WARN
log4j.appender.W.layout = org.apache.log4j.PatternLayout
log4j.appender.W.layout.ConversionPattern = [%d{yyyy-MM-dd HH:mm:ss,SSS}] [ %t:%r ] %5p %l - %m%n

### 输出ERROR级别以上的日志到logs/error.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File = logs/error.log
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = [%d{yyyy-MM-dd HH:mm:ss,SSS}] [ %t:%r ] %5p %l - %m%n