我有以下可绘制文件 button.xml：
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/button_down" android:state_enabled="true" android:state_pressed="true"/>
<item android:drawable="@drawable/button_up" android:state_enabled="true" android:state_pressed="false"/>
</selector>
这两个项目都是 XML 可绘制的，它们都单独工作：button_down.xml 和 button_up.xml。
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
<corners android:radius="10dp" />
<gradient
android:angle="90"
android:centerColor="#FFBD21"
android:endColor="#FFAE18"
android:gradientRadius="60"
android:startColor="#FFD060"
android:type="linear"
android:useLevel="false" />
</shape>
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
<corners android:radius="10dp" />
<gradient
android:angle="90"
android:centerColor="#FFBD21"
android:endColor="#FFD060"
android:gradientRadius="60"
android:startColor="#FFAE18"
android:type="linear"
android:useLevel="false" />
</shape>
但是当用作选择器的项目时出现以下错误。是否允许 XML 可绘制对象作为选择器的项目？
org.xmlpull.v1.XmlPullParserException: Binary XML file line #4: <item> tag requires a 'drawable' attribute or child tag defining a drawable
at android.graphics.drawable.StateListDrawable.inflate(StateListDrawable.java:178)
at android.graphics.drawable.Drawable.createFromXmlInner(Drawable.java:867)
at android.graphics.drawable.Drawable.createFromXml(Drawable.java:804)
at com.android.layoutlib.bridge.impl.ResourceHelper.getDrawable(ResourceHelper.java:208)
at android.content.res.BridgeTypedArray.getDrawable(BridgeTypedArray.java:774)
at android.view.View.<init>(View.java:2785)
at android.widget.TextView.<init>(TextView.java:449)
at android.widget.Button.<init>(Button.java:108)
at android.widget.Button.<init>(Button.java:104)
at sun.reflect.GeneratedConstructorAccessor17.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at android.view.LayoutInflater.createView(LayoutInflater.java:586)
at android.view.BridgeInflater.onCreateView(BridgeInflater.java:86)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:653)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:678)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:131)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:739)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:742)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:742)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:742)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:742)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:742)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:742)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
at android.view.LayoutInflater.inflate(LayoutInflater.java:372)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:321)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:322)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:325)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.RenderService.createRenderSession(RenderService.java:372)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1317)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1071)
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.onXmlModelChanged(GraphicalEditorPart.java:1033)
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditor.xmlModelChanged(LayoutEditor.java:317)
at com.android.ide.eclipse.adt.internal.editors.AndroidXmlEditor$XmlModelStateListener.modelChanged(AndroidXmlEditor.java:1405)
at org.eclipse.wst.sse.core.internal.model.AbstractStructuredModel.fireModelChanged(AbstractStructuredModel.java:553)
at org.eclipse.wst.sse.core.internal.model.AbstractStructuredModel.internalModelChanged(AbstractStructuredModel.java:887)
at org.eclipse.wst.sse.core.internal.model.AbstractStructuredModel.changedModel(AbstractStructuredModel.java:382)
at org.eclipse.wst.xml.core.internal.document.DOMModelImpl.changedModel(DOMModelImpl.java:167)
at org.eclipse.wst.sse.ui.StructuredTextEditor.savedModel(StructuredTextEditor.java:2687)
at org.eclipse.wst.sse.ui.StructuredTextEditor.doSave(StructuredTextEditor.java:1690)
at com.android.ide.eclipse.adt.internal.editors.AndroidXmlEditor.doSave(AndroidXmlEditor.java:524)
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditor.doSave(LayoutEditor.java:148)
at org.eclipse.ui.internal.SaveableHelper$2.run(SaveableHelper.java:151)
at org.eclipse.ui.internal.SaveableHelper$5.run(SaveableHelper.java:274)
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:464)
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:372)
at org.eclipse.jface.window.ApplicationWindow$1.run(ApplicationWindow.java:759)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.jface.window.ApplicationWindow.run(ApplicationWindow.java:756)
at org.eclipse.ui.internal.WorkbenchWindow.run(WorkbenchWindow.java:2579)
at org.eclipse.ui.internal.SaveableHelper.runProgressMonitorOperation(SaveableHelper.java:282)
at org.eclipse.ui.internal.SaveableHelper.runProgressMonitorOperation(SaveableHelper.java:261)
at org.eclipse.ui.internal.SaveableHelper.savePart(SaveableHelper.java:156)
at org.eclipse.ui.internal.EditorManager.savePart(EditorManager.java:1357)
at org.eclipse.ui.internal.WorkbenchPage.savePart(WorkbenchPage.java:3328)
at org.eclipse.ui.internal.WorkbenchPage.saveEditor(WorkbenchPage.java:3341)
at org.eclipse.ui.internal.SaveAction.run(SaveAction.java:76)
at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
at org.eclipse.jface.action.ActionContributionItem$6.handleEvent(ActionContributionItem.java:452)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3910)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3503)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:368)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514)
at org.eclipse.equinox.launcher.Main.run(Main.java:1311)