在《开发Spring MVC应用程序(1)》中，由于对log4j的配置有问题，导致log4j无法正常工作。现对log4j做如下修正：
# For JBoss: Avoid to setup log4j outside $JBOSS_HOME/server/default/deploy/log4j.xml!
# For all other servers: Comment out the Log4J listener in web.xml too.
log4j.rootLogger=INFO, stdout, logfile
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - <%m>%n
log4j.appender.logfile=org.apache.log4j.RollingFileAppender
log4j.appender.logfile.File=springapp.log
log4j.appender.logfile.MaxFileSize=512KB
# Keep three backup files.
log4j.appender.logfile.MaxBackupIndex=3
# Pattern to output: date priority [category] - message
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n
去掉第三行的注释，指定log文件名为springapp.log，并在log4j.properties同目录下创建该空文件。log4j.properties内容的具体含义可以参考《Log4j日志管理系统简单使用说明》
