idea+maven配置log4j详解

实现log4j打印日志依赖的jar包共3个，在pom.xml中加入相关依赖：

<!-- 添加log4j日志相关jar包:共3个jar-->
        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.25</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-log4j12 -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.25</version>
            <scope>test</scope>
        </dependency>

第二步，在项目的 src/test/resource目录下新建log4j.properties文件，文件内容为：

### set log levels ###
log4j.rootLogger = debug,stdout,R 

### console appender###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.Threshold = Info
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = %d [%t] %p [%c] - %m%n

### output to files ###
log4j.appender.R = org.apache.log4j.DailyRollingFileAppender
log4j.appender.R.File = logs/log.txt
log4j.appender.R.Append = true
log4j.appender.R.Threshold = Info 
log4j.appender.R.layout = org.apache.log4j.PatternLayout
#log4j.appender.R.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}-[%p]%m%n
log4j.appender.R.layout.ConversionPattern = %d [%t] %p [%c] - %m%n