有的说是 ClassPath过长,有的说是Eclipse插件导致
最后 在这里得到解决啦
http://code.google.com/p/googleappengine/issues/detail?id=1862
In C:\google\appengine-java-sdk-1.3.1\config\user\ant-macros.xml
Change line 102
from
<fileset dir="@{war}/WEB-INF/classes" includes="**/*.class"/>
to
<fileset dir="@{war}/WEB-INF/classes" includes="**/*JDO.class"/>