我的main-class文件绝对路径是E:\workplace\project\officeManage\classes\business\FTPServer.class
我执行的操作首先打普通包：jar cvf E:\workplace\project\officeManage\officeManage.jar E:\workplace\project\officeManage\classes
然后把officeManage.jar解压到本目录，修改Manifest.mf文件，增加 ： Main-Class: classes\business\FTPServer
再重新打包：java cvfm E:\workplace\project\officeManage\officeManage.jar E:\workplace\project\officeManage\META-INF\MANIFEST.MF E:\workplace\project\officeManage\classes
但是这样做下来用java -jar E:\workplace\project\officeManage\officeManage.jar运行的时候报错
Exception in thread "main " java.lang.NoClassDefFoundError
------解决方案--------------------
Main-Class: classes\business\FTPServer
Main-Class不是这么写的，Main-Class:package1.package2.UrMainClass