log4j编译通过,出现如下异常:

03-06-18 tcb

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Category.
我把log4j-1.2.8.jar放到C:\Tomcat 4.1.12\server\lib目录下,并且在classpath中也指定了路径.