Log4j输出日志到文件[配置]

log4j.properties:

log4j.rootLogger=DEBUG,console,FILE

log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.threshold=INFO
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} [%5p] - %c -%F(%L) -%m%n

log4j.appender.FILE=org.apache.log4j.RollingFileAppender
log4j.appender.FILE.Append=true
log4j.appender.FILE.File=../logs/log4jtest.log
log4j.appender.FILE.Threshold=INFO
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} [%5p] - %c -%F(%L) -%m%n
log4j.appender.FILE.MaxFileSize=10MB

默认将log4j.properties放置在classpath. 以上将日志文件保存至$TOMCAT_HOME/logs 目录

业务类中初始化日志器

private static Logger log = Logger.getLogger(LogoutServlet.class);

打印日志

log.info("user ["+username+"] is logout");