log4j 学习一下
Logger - 日志写出器，供程序员输出日志信息
Appender - 日志目的地，把格式化好的日志信息输出到指定的地方去
ConsoleAppender - 目的地为控制台的Appender
FileAppender - 目的地为文件的Appender
RollingFileAppender - 目的地为大小受限的文件的Appender
Layout - 日志格式化器，用来把程序员的logging request格式化成字符串
PatternLayout - 用指定的pattern格式化logging request的Layout
Logger的输出方法:
Logger类对象提供一系列方法供程序员输出日志信息：
log4j.rootLogger = DEBUG,stdout,D,E ##,stdoutlog4j.appender.stdout = org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.Target = System.outlog4j.appender.stdout.layout = org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} %5p :%L - %m%nlog4j.appender.stdout.Threshold = error #Dlog4j.appender.D = org.apache.log4j.RollingFileAppenderlog4j.appender.D.File = d:/work/logs/javacms/javacms-debug.loglog4j.appender.D.MaxFileSize=1000KBlog4j.appender.D.Append = truelog4j.appender.D.layout = org.apache.log4j.PatternLayoutlog4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m%nlog4j.appender.D.Threshold = DEBUG #Elog4j.appender.E = org.apache.log4j.RollingFileAppenderlog4j.appender.E.File = d:/work/logs/javacms/javacms-error.log log4j.appender.E.Append = truelog4j.appender.E.MaxFileSize=1000KBlog4j.appender.E.layout = org.apache.log4j.PatternLayoutlog4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss} [ %t:%r ] - [ %p ] %m%n log4j.appender.E.Threshold = ERROR