<span style="color:#ff0000;">Exception in thread "Thread-10" java.lang.UnsupportedClassVersionError: Bad version number in .class file
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(Unknown Source)
	at java.security.SecureClassLoader.defineClass(Unknown Source)
	at java.net.URLClassLoader.defineClass(Unknown Source)
	at java.net.URLClassLoader.access$100(Unknown Source)
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClassInternal(Unknown Source)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Unknown Source)
	at nc.ui.sm.cmenu.DesktopListenerImplClass.getDesktopListener(DesktopListenerImplClass.java:56)
	at nc.ui.sm.cmenu.Desktop.dispatchDesktopEvent(Desktop.java:1677)
	at nc.ui.sm.cmenu.Desktop.init(Desktop.java:620)
	at nc.ui.sm.login.LoginUIControl.showDesktop(LoginUIControl.java:237)
	at nc.ui.sm.login.LoginUISupport$LoginAction$1.run(LoginUISupport.java:346)
	at java.lang.Thread.run(Unknown Source)</span>
 

用友NC57   啟動 jstart客戶端 ，報錯 如上 ，解決方案：  

  更換 eclipse  -  complier  裡的 jdk版本  為jdk6  ,做完開發後， 切換成jdk5  再出補丁。