RCP运行时的NoClassDefFoundError

想象：运行RCP application 时有exception，但编译无错误

Exception in thread "Thread-7" java.lang.NoClassDefFoundError: org/jdom/input/SAXBuilder  
    at org.geonames.WebService.search(WebService.java:783)  
    at geo.GeocoderGeonames$SearchThread.run(GeocoderGeonames.java:119)  
Caused by: java.lang.ClassNotFoundException: org.jdom.input.SAXBuilder  
    at org.eclipse.osgi.framework.internal.core.BundleLoader.findClassInternal(BundleLoader.java:483)  
    at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:399)  
    at org.eclipse.osgi.framework.internal.core.BundleLoader.findClass(BundleLoader.java:387)  
    at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:87)  
    at java.lang.ClassLoader.loadClass(Unknown Source)  
    at java.lang.ClassLoader.loadClassInternal(Unknown Source)  
    ... 2 more

原因：RCP运行时加载的jar 和 外边文件，不以project configuration里面的设置为准，而是以MANIFEST.MF的配置为准。

解决：在Plug-in editor的Dependencies Tab中的Required Plug-ins 加入相对应的Plug-in ，或者是在Plug-in editor的Runtime Tab中Classpath中加入external jar