错误EclipseLink-4021在运行时创建EntityManager时为什么？

Question

我想在运行时创建的EntityManager，所以我可以从config.xml中

这里设置不同的用户名和密码是创造了EntityManager

map.put(PersistenceUnitProperties.JDBC_USER, SystemConfig.getConfig().getString("jdbcUser")); 
map.put(PersistenceUnitProperties.JDBC_PASSWORD, SystemConfig.getConfig().getString("jdbcPassword")); 
map.put(PersistenceUnitProperties.JDBC_URL, SystemConfig.getConfig().getString("jdbcUrl")); 
map.put(PersistenceUnitProperties.JDBC_DRIVER, "net.sourceforge.jtds.jdbc.Driver"); 
EntityManager eMgr = Persistence.createEntityManagerFactory("myPU", map).createEntityManager(); 

在UNIX我的程序结构的代码： 〜/测试/ myProgram.jar 〜/测试/ lib目录/ *。JAR但是（所有图书馆和了jdbc.jar这里）

当我运行该文件夹/测试程序里面的程序工作正常/ 当我在根目录下运行程序〜/我得到Ex ception [EclipseLink-4021]。 任何想法为什么？

注意：最终我需要使用cron作业来安排程序。

[EL Info]: 2013-05-06 12:10:18.989--ServerSession(1729331687)--EclipseLink, version: Eclipse Persistence Services - 2.4.1.v20121003-ad44345 
[EL Severe]: ejb: 2013-05-06 12:10:19.002--ServerSession(1729331687)--Exception [EclipseLink-4021] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.DatabaseException 
Exception Description: Unable to acquire a connection from driver [net.sourceforge.jtds.jdbc.Driver], user [null] and URL [null]. Verify that you have set the expected driver class and URL. Check your login, persistence.xml or sessions.xml resource. The jdbc.driver property should be set to a class that is compatible with your database platform 
Exception in thread "main" javax.persistence.PersistenceException: Exception [EclipseLink-4021] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.DatabaseException 
Exception Description: Unable to acquire a connection from driver [net.sourceforge.jtds.jdbc.Driver], user [null] and URL [null]. Verify that you have set the expected driver class and URL. Check your login, persistence.xml or sessions.xml resource. The jdbc.driver property should be set to a class that is compatible with your database platform 
     at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:602) 
     at org.eclipse.persistence.internal.jpa.EntityManagerFactoryDelegate.getDatabaseSession(EntityManagerFactoryDelegate.java:186) 
     at org.eclipse.persistence.internal.jpa.EntityManagerFactoryDelegate.createEntityManagerImpl(EntityManagerFactoryDelegate.java:278) 
     at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManagerImpl(EntityManagerFactoryImpl.java:304) 
     at org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:282) 
     at dcsmailcheck.MailResend.<init>(MailResend.java:61) 
     at dcsmailcheck.Main.main(Main.java:49) 
Caused by: Exception [EclipseLink-4021] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.DatabaseException 
Exception Description: Unable to acquire a connection from driver [net.sourceforge.jtds.jdbc.Driver], user [null] and URL [null]. Verify that you have set the expected driver class and URL. Check your login, persistence.xml or sessions.xml resource. The jdbc.driver property should be set to a class that is compatible with your database platform 
     at org.eclipse.persistence.exceptions.DatabaseException.unableToAcquireConnectionFromDriverException(DatabaseException.java:376) 
     at org.eclipse.persistence.sessions.DefaultConnector.connect(DefaultConnector.java:91) 
     at org.eclipse.persistence.sessions.DatasourceLogin.connectToDatasource(DatasourceLogin.java:162) 
     at org.eclipse.persistence.internal.sessions.DatabaseSessionImpl.loginAndDetectDatasource(DatabaseSessionImpl.java:685) 
     at org.eclipse.persistence.internal.jpa.EntityManagerFactoryProvider.login(EntityManagerFactoryProvider.java:215) 
     at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.deploy(EntityManagerSetupImpl.java:542) 
     ... 6 more 

Answer 1

由于您的代码在〜/ test文件夹中工作，似乎SystemConfig.getConfig()无法加载该位置的属性。确保已将您的属性的路径添加到CLASSPATH。