package test;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;public class Log4jTest {    private static Log logger = LogFactory.getLog(Log4jTest.class);     public static void main(String[] args) {        logger.error("ERROR");        logger.debug("DEBUG");        logger.warn("WARN");        logger.info("INFO");        logger.trace("TRACE");        System.out.println(logger.getClass());    }}

1 将commons-logging-1.0.4.jar，log4j.jar放入新建文件夹lib下，然后选中二者，build path 后，classpath发生了改变

2 添加 \bin\log4j.properties

# log4j configuration used during build and unit testslog4j.rootLogger=info,stdout,Rlog4j.threshhold=ALLlog4j.appender.stdout=org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.layout=org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern=%d{ISO8601} %-5p %c{2} (%F:%M(%L)) - %m%nlog4j.appender.R=org.apache.log4j.RollingFileAppenderlog4j.appender.R.File=test.txtlog4j.appender.R.MaxFileSize=100KBlog4j.appender.R.MaxBackupIndex=0log4j.appender.R.layout=org.apache.log4j.PatternLayoutlog4j.appender.R.layout.ConversionPattern=%d{ISO8601} %-5p %c{2} (%F:%M(%L)) - %m%n

运行，日志文件位置：log4jtest\test.txt