java.lang.NoClassDefFoundError：javax / mail / MessagingException

我一直在研究一个使用 Javamail API根据时间事件和某些条件发送电子邮件的程序.该程序在 Eclipse(最新版本)中运行完美,javamail和激活器jar在构建路径中,javamail的依赖项也是如此.当我将项目导出为jar并尝试运行它时,会出现问题. (生成的堆栈跟踪与Eclipse构建路径中缺少javamail jar时的堆栈跟踪相同).

堆栈跟踪如下：

`Exception in thread "Timer-1" java.lang.NoClassDefFoundError: javax/mail/MessagingException
at SpaceCheck.HourlySpaceAlerts(SpaceCheck.java:212)
at WarningReports.run(WarningReports.java:21)
at java.util.TimerThread.mainLoop(UnkNown Source)
at java.util.TimerThread.run(UnkNown Source)
Caused by: java.lang.classNotFoundException: javax.mail.MessagingException
at java.net.urlclassloader$1.run(UnkNown Source)
at java.net.urlclassloader$1.run(UnkNown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.urlclassloader.findClass(UnkNown Source)
at java.lang.classLoader.loadClass(UnkNown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(UnkNown Source)
at java.lang.classLoader.loadClass(UnkNown Source)
... 4 more`

谢谢您的帮助.

Class-Path: lib/javamail.jar