java.lang.ClassCastException : com. kk.COUNTRY 无法转换为 javax.xml.bind.JAXBElement

Question

我的主要类(class)是

    public static void main(String[] args) throws JAXBException,
        FileNotFoundException {

    Class[] classes = new Class[5];
    classes[0] = com.kk.AddressDetails.class;
    classes[1] = com.kk.COUNTRY.class;
    classes[2] = com.kk.ObjectFactory.class;
    classes[3] = com.kk.Details.class;
    classes[4] = com.kk.Districts.class;

    JAXBContext context = JAXBContext.newInstance(classes);

    Unmarshaller unmarshaller = context.createUnmarshaller();

    JAXBElement<COUNTRY> unmarshal = (JAXBElement<COUNTRY>) unmarshaller
            .unmarshal(new File("src\\countrydetails.xml"));
    COUNTRY value = unmarshal.getValue();
            System.out.println(value);

因此，在编译时，我在线程“main”java.lang.ClassCastException中遇到了此异常:com.kk.COUNTRY无法转换为javax.xml.bind.JAXBElement 在 main.kk.ClientApp.main(ClientApp.java:31)

Answer 1

自从您的 COUNTRY类注释为 @XmlRootElement这意味着它与根元素唯一关联，解码操作的结果将是 COUNTRY

COUNTRY c = (COUNTRY) unmarshaller.unmarshal(xml);

如果改为 COUNTRY有一个或多个对应的@XmlElementDecl注释或者您使用了 unmarshal采取 Class 的方法参数，您将获得 JAXBElement 的实例

JAXBElement<COUNTRY> c = unmarshaller.unmarshal(xml, COUNTRY.class);

了解更多信息

• http://blog.bdoughan.com/2012/07/jaxb-and-root-elements.html