java - JAXB异常 : SaveButton nor any of its super class is known to this context

Question

我已经阅读了有关此主题的多个主题，但似乎没有一个能回答我的具体问题。在包“settings”中，我有一个 SettingModel.java 类，它使用 jaxb 从 default.xml 文件加载默认设置。这工作完美无缺。然后，在同一个包下，在名为 SettingsWidgets 的子包内，我有一个 SaveButton.java 类，它有一个 setOnMouseClick eventListener，触发方法“saveSettings”。该代码部分工作:当前文件被覆盖(尽管为空)或在所需的包中创建了新的(但为空)xml 文件，并且我收到错误

javax.xml.bind.JAXBException: class settings.settingsWidgets.SaveButton nor any of its super class is known to this context.

<小时/>

我尝试过:
按照 Stack O 上几个线程中建议的不同方式创建 JAXBContext (将包作为字符串传递并添加 jaxb.in​​dex 和 ObjectFactory.java ，传递完整的类路径而不仅仅是类，...)无济于事，在我看来(阅读错误)问题不在于我如何将 SettingsModel 类传递给上下文...
@XmlSeealso 解决方法也经常被提及，但在我的例子中我没有立即看到它有任何用途(这并不是说我试图编码(marshal)子类或某种东西)
还尝试将 SaveButton.java 从子包中重构出来，使其与 SettingsModel 处于同一级别，但这并没有改变任何内容...
我完全不知道如何以及为什么应该将 SaveButton 包含到 jaxbContext 中，当我尝试时，我收到很多错误。

<小时/>

我的代码:

// SettingsModel.java

@XmlRootElement(name = "robot")
@XmlAccessorType(XmlAccessType.FIELD)
public class SettingsModel implements Observable {

    private boolean valid = true;

    //registered views List
    //annotate as Type Object.Class because JAXB cannot handle interfaces
    @XmlElement(type = Object.class)
    private  ArrayList<InvalidationListener> listenersList;

    //list all variable robot/vehicle specs
    //filename is needed for saving to current or new file
    @XmlElement(name = "filename")
    private String fileName;

    @XmlElement(name = "vehicle-width")
    private double vehicleWidth;

    @XmlElement(name = "work-width")
    private double workWidth;

    // other getters and setters without logic are removed

    public void setValid(boolean valid) {
        if (valid != this.valid) {
            this.valid = valid;

            fireInvalidationEvent();
        }
    }

    public void setVehicleWidth(double vehicleWidth) {
        this.vehicleWidth = vehicleWidth;

        Field.getInstance().getRobot().setVehicleWidth(vehicleWidth);
        fireInvalidationEvent();
    }

    public void setWorkWidth(double workWidth) {
        this.workWidth = workWidth;

        // Field.getInstance().getRobot().setVehicleWidth(vehicleWidth);
        // fireInvalidationEvent();
    }



    //METHODS AND FUNCTIONS
    @Override
    public void addListener(InvalidationListener invalidationListener) {
        listenersList.add(invalidationListener);
    }

    @Override
    public void removeListener(InvalidationListener invalidationListener) {
        listenersList.remove(invalidationListener);
    }

    public void fireInvalidationEvent() {
        for (InvalidationListener listener : listenersList) {
            listener.invalidated(this);
        }
    }
}

// SaveButton.java

public class SaveButton extends Button implements InvalidationListener {

    private SettingsModel model;

    public SaveButton(SettingsModel model) {
        this.model = model;
        model.addListener(this);
        setText("SAVE SETTINGS");
        setOnMouseClicked((ev)->{
            try {
                saveSettings();
            } catch (JAXBException e) {
                e.printStackTrace();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        });
    }

    private void saveSettings() throws JAXBException, FileNotFoundException {
        String filename = model.getFileName();

        Object[] options = {"Save", "Save As"};

        //choose Save or Save As
        int choice = JOptionPane.showOptionDialog(null,"Overwrite current file or Save As New file?",
                "Save Settings",
                JOptionPane.WARNING_MESSAGE,
                JOptionPane.YES_NO_OPTION,
                null,
                options,
                options[0]
                );

        if(choice != JOptionPane.OK_OPTION){
            filename = JOptionPane.showInputDialog("Enter new file name");
            model.setFileName(filename);
        }

        System.out.println(model.getFileName());

        //Marshal
        JAXBContext jaxbContext = JAXBContext.newInstance(SettingsModel.class);

        Marshaller jaxbMarshaller = jaxbContext.createMarshaller();

        //if filename stays same, file is overwritten. Test only SAVE AS until code works to not lose default file
        File file = new File("src/resources/properties/"+ filename + ".xml");

        OutputStream os = new FileOutputStream(file);

        jaxbMarshaller.marshal(model,os);
    }

    @Override
    public void invalidated(Observable observable) {
        System.out.println("button invalidated: "+ model.isValid());

        setDisable(!model.isValid());
    }
}

<小时/>

堆栈跟踪:

javax.xml.bind.MarshalException
 - with linked exception:
[com.sun.istack.SAXException2: javax.xml.bind.JAXBException: class settings.settingsWidgets.SaveButton nor any of its super class is known to this context.
javax.xml.bind.JAXBException: class settings.settingsWidgets.SaveButton nor any of its super class is known to this context.]
    at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:301)
    at com.sun.xml.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:226)
    at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:80)
    at settings.settingsWidgets.SaveButton.saveSettings(SaveButton.java:59)
    at settings.settingsWidgets.SaveButton.lambda$new$0(SaveButton.java:27)
    at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics/javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:3564)
    at javafx.graphics/javafx.scene.Scene$ClickGenerator.access$8200(Scene.java:3492)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3860)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.access$1200(Scene.java:3579)
    at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849)
    at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2588)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:434)
    at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:390)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
    at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
    at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: com.sun.istack.SAXException2: javax.xml.bind.JAXBException: class settings.settingsWidgets.SaveButton nor any of its super class is known to this context.
javax.xml.bind.JAXBException: class settings.settingsWidgets.SaveButton nor any of its super class is known to this context.
    at com.sun.xml.bind.v2.runtime.XMLSerializer.reportError(XMLSerializer.java:217)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.reportError(XMLSerializer.java:232)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:623)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementNodeProperty.serializeItem(ArrayElementNodeProperty.java:39)
    at com.sun.xml.bind.v2.runtime.property.ArrayElementProperty.serializeListBody(ArrayElementProperty.java:142)
    at com.sun.xml.bind.v2.runtime.property.ArrayERProperty.serializeBody(ArrayERProperty.java:129)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:329)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsSoleContent(XMLSerializer.java:563)
    at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.serializeRoot(ClassBeanInfoImpl.java:310)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:464)
    at com.sun.xml.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:298)
    ... 34 more
Caused by: javax.xml.bind.JAXBException: class settings.settingsWidgets.SaveButton nor any of its super class is known to this context.
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getBeanInfo(JAXBContextImpl.java:563)
    at com.sun.xml.bind.v2.runtime.XMLSerializer.childAsXsiType(XMLSerializer.java:618)
    ... 42 more

Process finished with exit code 0

任何见解将不胜感激。

Answer 1

您的 SettingsModel 有一个标记为 xml 元素的监听器列表。您可以使用以下行将 SaveButton 添加到列表中: model.addListener(this);

因此，在编码 SettingsModel 时，JAXB 处理 ListenerList 并尝试编码 SaveButton，但它不知道如何执行此操作。

向 SaveButton 类添加 @XmlRootElement 注释就足够了。

此外，我看到每次单击按钮时都会创建一个 JAXBContext。 JAXB 规范说:

To avoid the overhead involved in creating a JAXBContext instance, a JAXB application is encouraged to reuse a JAXBContext instance. An implementation of abstract class JAXBContext is required to be thread-safe, thus, multiple threads in an application can share the same JAXBContext instance.

您应该将 JAXBContext 移至静态字段，因为该实例可以重用。