1、在META-INF\MANIFEST.MF中指定Main-Class
Main-Class: test.HelloWorld
命令:java -jar fileName.jar
2、不指定Main-Class,在运行时指定想要运行的类
命令:java -cp fileName.jar org.test.HelloWorld
当当开源作业框架:http://dangdangdotcom.github.io/elastic-job/