在EMF里可以用XML Schema定义模型，然后转换为genmodel模型，但我这里在生成genmodel向导的第四步按Load后会产生一个NullPointerException如下，导致无法继续：
java.lang.NullPointerException
at org.apache.crimson.tree.ElementNode2.getAttributeNodeNS(ElementNode2.java: 432 )
at org.apache.crimson.tree.ElementNode2.hasAttributeNS(ElementNode2.java: 388 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.getEcoreAttribute(XSDEcoreBuilder.java: 2336 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.getEcoreAttribute(XSDEcoreBuilder.java: 2329 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.getEStructuralFeature(XSDEcoreBuilder.java: 2004 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.generate(XSDEcoreBuilder.java: 2117 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.generate(XSDEcoreBuilder.java: 2067 )
at org.eclipse.xsd.ecore.importer.XSDImporter.doComputeEPackages(XSDImporter.java: 123 )
at org.eclipse.emf.importer.ModelImporter.computeEPackages(ModelImporter.java: 664 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage.refreshModel(ModelDetailPage.java: 488 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage$ 2 .execute(ModelDetailPage.java: 434 )
at org.eclipse.ui.actions.WorkspaceModifyOperation$ 1 .run(WorkspaceModifyOperation.java: 98 )
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java: 1719 )
at org.eclipse.ui.actions.WorkspaceModifyOperation.run(WorkspaceModifyOperation.java: 110 )
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java: 346 )
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java: 291 )
at org.eclipse.jface.wizard.WizardDialog.run(WizardDialog.java: 830 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage.refreshModel(ModelDetailPage.java: 457 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage.doHandleEvent(ModelDetailPage.java: 241 )
at org.eclipse.xsd.ecore.importer.ui.XSDDetailPage.doHandleEvent(XSDDetailPage.java: 91 )
at org.eclipse.emf.importer.ui.contribution.base.ModelImporterPage.handleEvent(ModelImporterPage.java: 106 )
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java: 66 )
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java: 1021 )
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java: 2867 )
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java: 2572 )
at org.eclipse.jface.window.Window.runEventLoop(Window.java: 809 )
at org.eclipse.jface.window.Window.open(Window.java: 787 )
at org.eclipse.ui.actions.NewWizardAction.run(NewWizardAction.java: 181 )
at org.eclipse.ui.actions.NewWizardDropDownAction.run(NewWizardDropDownAction.java: 174 )
at org.eclipse.jface.action.Action.runWithEvent(Action.java: 996 )
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java: 538 )
at org.eclipse.jface.action.ActionContributionItem.access$ 2 (ActionContributionItem.java: 488 )
at org.eclipse.jface.action.ActionContributionItem$ 6 .handleEvent(ActionContributionItem.java: 441 )
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java: 66 )
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java: 1021 )
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java: 2867 )
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java: 2572 )
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java: 1699 )
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java: 1663 )
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java: 367 )
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java: 143 )
at org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplication.java: 103 )
at org.eclipse.core.internal.runtime.PlatformActivator$ 1 .run(PlatformActivator.java: 226 )
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java: 376 )
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java: 163 )
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java: 39 )
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java: 25 )
at java.lang.reflect.Method.invoke(Method.java: 324 )
at org.eclipse.core.launcher.Main.invokeFramework(Main.java: 334 )
at org.eclipse.core.launcher.Main.basicRun(Main.java: 278 )
at org.eclipse.core.launcher.Main.run(Main.java: 973 )
at org.eclipse.core.launcher.Main.main(Main.java: 948 )
at org.apache.crimson.tree.ElementNode2.getAttributeNodeNS(ElementNode2.java: 432 )
at org.apache.crimson.tree.ElementNode2.hasAttributeNS(ElementNode2.java: 388 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.getEcoreAttribute(XSDEcoreBuilder.java: 2336 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.getEcoreAttribute(XSDEcoreBuilder.java: 2329 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.getEStructuralFeature(XSDEcoreBuilder.java: 2004 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.generate(XSDEcoreBuilder.java: 2117 )
at org.eclipse.xsd.ecore.XSDEcoreBuilder.generate(XSDEcoreBuilder.java: 2067 )
at org.eclipse.xsd.ecore.importer.XSDImporter.doComputeEPackages(XSDImporter.java: 123 )
at org.eclipse.emf.importer.ModelImporter.computeEPackages(ModelImporter.java: 664 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage.refreshModel(ModelDetailPage.java: 488 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage$ 2 .execute(ModelDetailPage.java: 434 )
at org.eclipse.ui.actions.WorkspaceModifyOperation$ 1 .run(WorkspaceModifyOperation.java: 98 )
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java: 1719 )
at org.eclipse.ui.actions.WorkspaceModifyOperation.run(WorkspaceModifyOperation.java: 110 )
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java: 346 )
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java: 291 )
at org.eclipse.jface.wizard.WizardDialog.run(WizardDialog.java: 830 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage.refreshModel(ModelDetailPage.java: 457 )
at org.eclipse.emf.importer.ui.contribution.base.ModelDetailPage.doHandleEvent(ModelDetailPage.java: 241 )
at org.eclipse.xsd.ecore.importer.ui.XSDDetailPage.doHandleEvent(XSDDetailPage.java: 91 )
at org.eclipse.emf.importer.ui.contribution.base.ModelImporterPage.handleEvent(ModelImporterPage.java: 106 )
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java: 66 )
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java: 1021 )
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java: 2867 )
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java: 2572 )
at org.eclipse.jface.window.Window.runEventLoop(Window.java: 809 )
at org.eclipse.jface.window.Window.open(Window.java: 787 )
at org.eclipse.ui.actions.NewWizardAction.run(NewWizardAction.java: 181 )
at org.eclipse.ui.actions.NewWizardDropDownAction.run(NewWizardDropDownAction.java: 174 )
at org.eclipse.jface.action.Action.runWithEvent(Action.java: 996 )
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java: 538 )
at org.eclipse.jface.action.ActionContributionItem.access$ 2 (ActionContributionItem.java: 488 )
at org.eclipse.jface.action.ActionContributionItem$ 6 .handleEvent(ActionContributionItem.java: 441 )
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java: 66 )
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java: 1021 )
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java: 2867 )
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java: 2572 )
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java: 1699 )
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java: 1663 )
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java: 367 )
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java: 143 )
at org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplication.java: 103 )
at org.eclipse.core.internal.runtime.PlatformActivator$ 1 .run(PlatformActivator.java: 226 )
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java: 376 )
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java: 163 )
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java: 39 )
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java: 25 )
at java.lang.reflect.Method.invoke(Method.java: 324 )
at org.eclipse.core.launcher.Main.invokeFramework(Main.java: 334 )
at org.eclipse.core.launcher.Main.basicRun(Main.java: 278 )
at org.eclipse.core.launcher.Main.run(Main.java: 973 )
at org.eclipse.core.launcher.Main.main(Main.java: 948 )
这是由Sun JDK1.4的一个bug造成的，解决方法是通过参数指定eclipse使用第三方的XML Parser，例如Xerces-J。首先 下载Xerces-J 并解压缩，然后在eclipse的启动参数后加上“-vmargs -Djava.endorsed.dirs=<path-to-your-xerces-jars-folder>”即可。
EMF关于这个问题的说明：XSD Model Loading: Crimson DOM Bug, Workaround & Download
本文转自博客园八进制的博客，原文链接：EMF不能载入schema问题的解决，如需转载请自行联系原博主。
