java我在尝试log4j时遇到以下错误。

Question

我在使用log4j时出现以下错误。有人能猜出问题出在哪里吗？ 提前谢谢

log4j:ERROR A "org.apache.log4j.ConsoleAppender" object is not assignable to a "org.apache.log4j.Appender" variable.

log4j:ERROR The class "org.apache.log4j.Appender" was loaded by 

log4j:ERROR [sun.misc.Launcher$AppClassLoader@43540a77] whereas object of type 

log4j:ERROR "org.apache.log4j.ConsoleAppender" was loaded by [WebAppClassLoader].

log4j:ERROR Could not instantiate appender named "stdout".

这些是用log4j写的行。属性文件

log4j.rootLogger=error, stdout

log4j.logger.java.sql=error
log4j.logger.com.example.test=error

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{DATE} %5p %c{1}:%L - %m%n