簡單介紹log4j一般的使用步驟

og4j.rootLogger=debug, stdout, R

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# Pattern to output the caller´s file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%d %5p [%t] (%F:%L) - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=YesFTP.log

log4j.appender.R.MaxFileSize=1000KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=1

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%d %5p [%t] (%F:%L) - %m%n

2、在入口類的靜態區初始化log4j

 static {
  PropertyConfigurator.configure(
   YesFTPClientFrame.class.getResource("log4j.propertIEs"));
 }

3、在每一個需要log的地方都初始化一個私有靜態的變量

 private static Logger logger = Logger.getLogger(xx.class);

4、使用log4j提供的方法

logger.info(”hello”);

5、用log4j輸出異常的堆棧信息

logger.error("oops, got an exception: ", e);