JAXB xsi：类型子类unmarshalling不起作用 [英] JAXB xsi:type subclass unmarshalling not working

问题描述

我正在按照这个经常被引用的博客文章使用xsi：type的说明：

I'm following the instructions on using xsi:type from this oft-cited blog post:

http://blog.bdoughan.com/2010/11/jaxb-and-inheritance-using-xsitype.html

基本上我有这个：

public abstract class ContactInfo {
}

public class Address extends ContactInfo {

    private String street;

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }
}

@XmlRootElement
public class Customer {

    private ContactInfo contactInfo;

    public ContactInfo getContactInfo() {
        return contactInfo;
    }

    public void setContactInfo(ContactInfo contactInfo) {
        this.contactInfo = contactInfo;
    }
}

此测试：

@Test
public void contactTestCase() throws JAXBException, ParserConfigurationException, IOException, SAXException {
    Customer customer = new Customer();
    Address address = new Address();
    address.setStreet("1 A Street");
    customer.setContactInfo(address);

    JAXBContext jc = JAXBContext.newInstance(Customer.class, Address.class, PhoneNumber.class);
    StringWriter writer = new StringWriter();
    Marshaller marshaller = jc.createMarshaller();
    marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
    marshaller.marshal(customer, writer);
    String s = writer.toString();
    System.out.append(s);

    StringInputStream sis = new StringInputStream(s);
    DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder db = documentBuilderFactory.newDocumentBuilder();
    Document doc = db.parse(sis);

    Unmarshaller um = jc.createUnmarshaller();
    JAXBElement result = um.unmarshal(doc, Customer.class);
    Customer f = (Customer) result.getValue();

    writer = new StringWriter();
    marshaller.marshal(customer, writer);
    s = writer.toString();
    System.out.append(s);
}

我得到这个结果：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer>
    <contactInfo xsi:type="address" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
        <street>1 A Street</street>
    </contactInfo>
</customer>

javax.xml.bind.UnmarshalException: Unable to create an instance of blog.inheritance.ContactInfo

我已经尝试了JAXB的默认实现，jaxb-impl-2.1.2并基于此 bug ，我试过jaxb-impl-2.2.6-b38.jar。它都不起作用。

I've tried the default implementation of JAXB, jaxb-impl-2.1.2 and based off this bug, I've tried jaxb-impl-2.2.6-b38.jar. None of it works.

这不应该工作还是我错过了一些设置？

Is this not supposed to work or am I missing some setup?

推荐答案

在您的测试用例中，您需要指定 DocumentBuilderFactory 是否可识别名称空间。如果没有此设置，JAXB实现的DOM输入将不包含正确形成的 xsi：type 属性。

In your test case you need to specify that the DocumentBuilderFactory is namespace aware. Without this setting the DOM input to your JAXB implemenation won't contain a properly formed xsi:type attribute.

    documentBuilderFactory.setNamespaceAware(true);

这篇关于JAXB xsi：类型子类unmarshalling不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！