在struts里应用log4j写日志

在struts里应用log4j写日志，一般是放在classes目录下的名字是log4j.propertyies或log4j.xml。log4j.xml功能比较强一点。例子的大概内容是这样的
                                                        
                                  
         
                                                                         
                                                                  
 

 
  
                                     value="%d %-5p [%t] %C (%F:%L) - %m%n"/>
  
 


 
  
  
        
          
  
                                     value="%d %-5p [%t] %C{2} (%F:%L) - %m%n"/>
  
  
        
          
        
      
 
 
  
  
        
         
  
                                     value="%d %-5p [%t] %C{2} (%F:%L) - %m%n"/>
                                                                        
  
         
             
                                                                          
                                                               
                        
                                             
                                                                     
                                         
                                             
                                                                      
                                                                         
                                         
                               
                                                                                
                                                                         
                                                    

其中append就一个日志的输出点，可以是文件，console或者其他(如mail).
如果是自己写程序时用，没有那么麻烦，建个log4j.properties
内容如下：
#levels: debug, info, warn, error, fatal         
log4j.rootCategory=DEBUG, 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
# ---------------- Attention here ----------------------------
log4j.appender.logfile.File=koala.log                                    
log4j.appender.logfile.MaxFileSize=512KB                         
# Keep three backup files                                                     
log4j.appender.logfile.MaxBackupIndex=3                          
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
# Pattern to output : date priority [category] - line_separator
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - <%m>%n
仔细看看，然后写一下就知道什么意思了。

然后写每个类时加一句话：
Log log = LogFactory.getLog(所在类名.class)，然后程序里就
if (log.isInfo) {
     log.info("信息");
}
写一下就知道了。