Question

这看起来像是一个已经解决的旧问题，但不幸的是我找不到一个好的参考。我有一个使用Javaassist的Java应用程序。它工作正常，直到我将其升级到webstart应用程序。现在Javaassist给了我一个classNotFoundException。该课程肯定是在课堂上。

我发现这篇相关的帖子https://community.jboss.org/message/302408有点老了，我无法解码它。有人可以在这里给我一个手吗？

感谢

以下是代码段：

 ctClasses = new HashMap<String, CtClass>();
    classPool = ClassPool.getDefault();

    try {
        ctEntity = classPool.get("org.myclass");
    } catch (NotFoundException e) {
        logger.error("Could not find entity class, this should not happen");
        throw new RuntimeException("Could not find Entity class",e);
    }

stacktrace中没有任何内容。

 java.lang.RuntimeException: Could not find Entity class
    at ca.cbc.panacea.metadata.JavassistClassGeneratorImpl.<init>(JavassistClassGeneratorImpl.java:32)
    at ca.cbc.panacea.metadata.ClassGeneratorFactory.getDefaultClassGenerator(ClassGeneratorFactory.java:12)
    at ca.cbc.panacea.metadata.ClassCreator.<init>(ClassCreator.java:30)
    at ca.cbc.panacea.Panacea.digestMappingFile(Panacea.java:75)
    at ca.cbc.panacea.console.PanaceaConsole.validateMappingFile(PanaceaConsole.java:46)
    at ca.cbc.panacea.console.PanaceaConsoleUI.actionPerformed(PanaceaConsoleUI.java:132)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6373)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6138)
    at java.awt.Container.processEvent(Container.java:2085)
    at java.awt.Component.dispatchEventImpl(Component.java:4735)
    at java.awt.Container.dispatchEventImpl(Container.java:2143)
    at java.awt.Component.dispatchEvent(Component.java:4565)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4621)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4282)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4212)
    at java.awt.Container.dispatchEventImpl(Container.java:2129)
    at java.awt.Window.dispatchEventImpl(Window.java:2478)
    at java.awt.Component.dispatchEvent(Component.java:4565)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:679)
    at java.awt.EventQueue.access$000(EventQueue.java:85)
    at java.awt.EventQueue$1.run(EventQueue.java:638)
    at java.awt.EventQueue$1.run(EventQueue.java:636)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
    at java.awt.EventQueue$2.run(EventQueue.java:652)
    at java.awt.EventQueue$2.run(EventQueue.java:650)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:649)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
     Caused by: javassist.NotFoundException: ca.cbc.panacea.metadata.Entity
    at javassist.ClassPool.get(ClassPool.java:436)
    at ca.cbc.panacea.metadata.JavassistClassGeneratorImpl.<init>       (JavassistClassGeneratorImpl.java:29)

问题实际上是ClassLoader。 JNLP使用与java命令行不同的类加载器。问题是如何将JNLP类加载器与Javassist进行协调。

Answer 1

关键是设置ClassPool以查看应用程序类的类加载器。这可以通过向ClassPool添加类路径来完成：

ctClasses = new HashMap<String, CtClass>();
classPool = ClassPool.getDefault();

//Add the classloader of your application's classes so Javassist can find them
ClassLoader loader = org.MyClass.class.getClassLoader();
pool.appendClassPath(new LoaderClassPath(loader));

try {
    ctEntity = classPool.get("org.MyClass");
} catch (NotFoundException e) {
    logger.error("Could not find entity class, this should not happen");
    throw new RuntimeException("Could not find Entity class",e);
}

您需要为任何未从系统类加载器加载其类的应用程序自定义类池的类路径，例如Web-start应用程序，Eclipse插件和在Java EE容器下运行的应用程序。

Javassist tutorial的类搜索路径部分下的更多详细信息。

Javassist和Web Start

1 个答案: