我目前正在开发一个旨在接受插件的项目。为了从他们的jar文件加载插件,我使用的是ClassLoader
。这是我用来加载插件的代码。
URLClassLoader loader = URLClassLoader.newInstance(new URL[] {pluginJar.toURI().toURL()}, this.getClass().getClassLoader());
try {
Class<?> clazz= Class.forName("msciplugin.PluginDriver", true, loader);
Constructor<?> constructor=clazz.getConstructor(ProgramManager.class);
MSCIPlugin plugin=(MSCIPlugin) constructor.newInstance(programManager);
plugins.add(plugin);
plugin.addMSCIPluginListener(this);
this.pluginAdded(plugin);
} catch (Exception e) {
e.printStackTrace();
return false;
}
loader.close();
当我运行程序时,我能够加载我创建的测试插件,但是稍后在程序中,我要求插件执行一个操作,该操作使用最初未使用的插件jar中的类。然后程序会抛出由NoClassDefFoundError
ClassNotFoundException
Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: msciplugin/TimeUtils
at msciplugin.ServerControllerConfigurationWindow.refreashEditor(ServerControllerConfigurationWindow.java:195)
at msciplugin.ServerControllerConfigurationWindow.valueChanged(ServerControllerConfigurationWindow.java:299)
at javax.swing.JList.fireSelectionValueChanged(Unknown Source)
at javax.swing.JList$ListSelectionHandler.valueChanged(Unknown Source)
at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
at javax.swing.DefaultListSelectionModel.changeSelection(Unknown Source)
at javax.swing.DefaultListSelectionModel.changeSelection(Unknown Source)
at javax.swing.DefaultListSelectionModel.setSelectionInterval(Unknown Source)
at javax.swing.JList.setSelectionInterval(Unknown Source)
at javax.swing.plaf.basic.BasicListUI$Handler.adjustSelection(Unknown Source)
at javax.swing.plaf.basic.BasicListUI$Handler.mousePressed(Unknown Source)
at java.awt.AWTEventMulticaster.mousePressed(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$400(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: msciplugin.TimeUtils
at java.net.URLClassLoader$1.run(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.net.FactoryURLClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 45 more
非常感谢任何帮助。
答案 0 :(得分:0)
我弄清楚问题是什么。加载类msciplugin.PluginDriver
时,URLClassLoader
未加载所需的所有其他类。我通过加载jar文件中的所有类来解决这个问题。我使用方法here来查找jar文件中的所有类。