从XmlStreamReader解组JAXB会导致空对象

Question

I created a Java procedure for unmarshalling an XML message where a "startTag" can be provided to start unmarshalling at a particular element within the message. 我创建了一个用于解组XML消息的Java过程，其中可以提供“ startTag”以在消息中的特定元素上开始解组。 I used an XMLStreamReader to make this selection. 我使用XMLStreamReader进行了选择。

A complete copy-pastable demo of the problem I run into is below. 下面是我遇到的问题的完整可复制复制的演示。 The 'xml' message is what I need to work with. 我需要使用“ xml”消息。 It unfortunately yields a null car object in the result, while the 'xmlStripped' message yields a fully unmarshalled result. 不幸的是，它会在结果中产生一个null汽车对象，而“ xmlStripped”消息会产生一个完全未编组的结果。

I isolated the problem to the xmlns="http://www.example.com/type" namespace in the <response> element. 我将问题隔离到<response>元素中的xmlns="http://www.example.com/type"命名空间。 When I remove this, the 'xml' is properly unmarshalled. 当我删除它时，“ xml”已正确解组。

I have no control over the XML. 我无法控制 XML。 The 'xml' variable is what I need to work with. 我需要使用'xml'变量。 I have little control over the XSD/ ObjectFactory , so my first course of action is to look for a solution in the unmarshalling procedure. 我对XSD / ObjectFactory 几乎没有控制权，所以我的第一步是在解组过程中寻找解决方案。

Please let me know if you know why this fails and if you have a solution. 如果您知道失败的原因以及解决方案，请告诉我。 Thanks! 谢谢！

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import javax.xml.bind.annotation.*;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.io.Reader;
import java.io.StringReader;

public class XmlStreamReaderUnmarshallingTest {

    private static JAXBContext jaxbContext;

    static {
        try {
            jaxbContext = JAXBContext.newInstance(ObjectFactory.class);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }

    private static String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
            "<soapenv:Envelope xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" \n" +
            "\txmlns:soapenv=\"http://schemas.xmlsoap.org/soap/envelope/\" \n" +
            "\txmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\">\n" +
            "\t<soapenv:Body>\n" +
            "\t\t<response xmlns=\"http://www.example.com/type\">\n" +
            "\t\t\t<type:serviceResponse xmlns:type=\"http://www.example.com/type\">\n" +
            "\t\t\t\t<Body>\n" +
            "\t\t\t\t\t<Car>\n" +
            "\t\t\t\t\t\t<Brand>Mitsubishi</Brand>\n" +
            "\t\t\t\t\t\t<Color>Red</Color>\n" +
            "\t\t\t\t\t</Car>\n" +
            "\t\t\t\t</Body>\n" +
            "\t\t\t</type:serviceResponse>\n" +
            "\t\t</response>\n" +
            "\t</soapenv:Body>\n" +
            "</soapenv:Envelope>";


    private static String xmlStripped = "<type:serviceResponse xmlns:type=\"http://www.example.com/type\">\n" +
            "\t\t\t\t<Body>\n" +
            "\t\t\t\t\t<Car>\n" +
            "\t\t\t\t\t\t<Brand>Mitsubishi</Brand>\n" +
            "\t\t\t\t\t\t<Color>Red</Color>\n" +
            "\t\t\t\t\t</Car>\n" +
            "\t\t\t\t</Body>\n" +
            "\t\t\t</type:serviceResponse>";


    public static void main(String[] args) throws JAXBException, XMLStreamException {
        readXml(xml, "serviceResponse");
        readXml(xmlStripped, "serviceResponse");
    }

    private static void readXml(String inputXml, String startFromElement) throws JAXBException, XMLStreamException {

        final XMLInputFactory xmlInputFactory = XMLInputFactory.newFactory();
        final Reader reader = new StringReader(inputXml);
        final XMLStreamReader xmlStreamReader = xmlInputFactory.createXMLStreamReader(reader);
        final XMLStreamReader streamReader = skipToElement(xmlStreamReader, startFromElement);
        final MyServiceResponse serviceResponse = (MyServiceResponse) unmarshal(streamReader);

        if(serviceResponse.getBody().getCar() == null) {
            System.out.println("It didn't work :-(");
        } else {
            System.out.println("It worked");
        }
    }

    private static XMLStreamReader skipToElement(final XMLStreamReader xsr, final String startAtElement) throws XMLStreamException {
        while (startAtElement != null && xsr.hasNext()) {
            xsr.next();
            if (xsr.hasName()) {
                final String name = xsr.getName().getLocalPart();
                if (name.equals(startAtElement)) {
                    return xsr;
                }
            }
        }

        throw new IllegalArgumentException(String.format("Could not find element %s in response", startAtElement));
    }

    private static Object unmarshal(final XMLStreamReader xsr) throws JAXBException {
        final Object entity = unmarshaller(jaxbContext).unmarshal(xsr);
        return (entity instanceof JAXBElement ? ((JAXBElement) entity).getValue() : entity);
    }

    // Create unmarshaller every time
    private static Unmarshaller unmarshaller(JAXBContext context) throws JAXBException {

        return context.createUnmarshaller();

    }
}


@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "MyServiceResponse", propOrder = {

})
class MyServiceResponse {

    @XmlElement(name = "Body")
    protected MyServiceResponse.Body body;

    /**
     * Gets the value of the body property.
     *
     * @return
     *     possible object is
     *     {@link MyServiceResponse.Body }
     *
     */
    public MyServiceResponse.Body getBody() {
        return body;
    }

    /**
     * Sets the value of the body property.
     *
     * @param value
     *     allowed object is
     *     {@link MyServiceResponse.Body }
     *
     */
    public void setBody(MyServiceResponse.Body value) {
        this.body = value;
    }


    /**
     * <p>Java class for anonymous complex type.
     *
     * <p>The following schema fragment specifies the expected content contained within this class.
     *
     * <pre>
     * &lt;complexType&gt;
     *   &lt;complexContent&gt;
     *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType"&gt;
     *       &lt;all&gt;
     *         &lt;element name="Car" minOccurs="0"&gt;
     *           &lt;complexType&gt;
     *             &lt;complexContent&gt;
     *               &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType"&gt;
     *                 &lt;all&gt;
     *                   &lt;element name="Brand" type="{http://www.w3.org/2001/XMLSchema}string" minOccurs="0"/&gt;
     *                   &lt;element name="Color" type="{http://www.w3.org/2001/XMLSchema}string" minOccurs="0"/&gt;
     *                 &lt;/all&gt;
     *               &lt;/restriction&gt;
     *             &lt;/complexContent&gt;
     *           &lt;/complexType&gt;
     *         &lt;/element&gt;
     *       &lt;/all&gt;
     *     &lt;/restriction&gt;
     *   &lt;/complexContent&gt;
     * &lt;/complexType&gt;
     * </pre>
     *
     *
     */
    @XmlAccessorType(XmlAccessType.FIELD)
    @XmlType(name = "", propOrder = {

    })
    public static class Body {

        @XmlElement(name = "Car")
        protected MyServiceResponse.Body.Car car;

        /**
         * Gets the value of the car property.
         *
         * @return
         *     possible object is
         *     {@link MyServiceResponse.Body.Car }
         *
         */
        public MyServiceResponse.Body.Car getCar() {
            return car;
        }

        /**
         * Sets the value of the car property.
         *
         * @param value
         *     allowed object is
         *     {@link MyServiceResponse.Body.Car }
         *
         */
        public void setCar(MyServiceResponse.Body.Car value) {
            this.car = value;
        }


        /**
         * <p>Java class for anonymous complex type.
         *
         * <p>The following schema fragment specifies the expected content contained within this class.
         *
         * <pre>
         * &lt;complexType&gt;
         *   &lt;complexContent&gt;
         *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType"&gt;
         *       &lt;all&gt;
         *         &lt;element name="Brand" type="{http://www.w3.org/2001/XMLSchema}string" minOccurs="0"/&gt;
         *         &lt;element name="Color" type="{http://www.w3.org/2001/XMLSchema}string" minOccurs="0"/&gt;
         *       &lt;/all&gt;
         *     &lt;/restriction&gt;
         *   &lt;/complexContent&gt;
         * &lt;/complexType&gt;
         * </pre>
         *
         *
         */
        @XmlAccessorType(XmlAccessType.FIELD)
        @XmlType(name = "", propOrder = {

        })
        public static class Car {

            @XmlElement(name = "Brand")
            protected String brand;
            @XmlElement(name = "Color")
            protected String color;

            /**
             * Gets the value of the brand property.
             *
             * @return
             *     possible object is
             *     {@link String }
             *
             */
            public String getBrand() {
                return brand;
            }

            /**
             * Sets the value of the brand property.
             *
             * @param value
             *     allowed object is
             *     {@link String }
             *
             */
            public void setBrand(String value) {
                this.brand = value;
            }

            /**
             * Gets the value of the color property.
             *
             * @return
             *     possible object is
             *     {@link String }
             *
             */
            public String getColor() {
                return color;
            }

            /**
             * Sets the value of the color property.
             *
             * @param value
             *     allowed object is
             *     {@link String }
             *
             */
            public void setColor(String value) {
                this.color = value;
            }

        }

    }

}


@XmlRegistry
class ObjectFactory {

    private final static QName _ServiceResponse_QNAME = new QName("http://www.example.com/type", "serviceResponse");

    /**
     * Create a new ObjectFactory that can be used to create new instances of schema derived classes for package: com.example.type
     *
     */
    public ObjectFactory() {
    }

    /**
     * Create an instance of {@link MyServiceResponse }
     *
     */
    public MyServiceResponse createMyServiceResponse() {
        return new MyServiceResponse();
    }

    /**
     * Create an instance of {@link MyServiceResponse.Body }
     *
     */
    public MyServiceResponse.Body createMyServiceResponseBody() {
        return new MyServiceResponse.Body();
    }

    /**
     * Create an instance of {@link MyServiceResponse.Body.Car }
     *
     */
    public MyServiceResponse.Body.Car createMyServiceResponseBodyCar() {
        return new MyServiceResponse.Body.Car();
    }

    /**
     * Create an instance of {@link JAXBElement }{@code <}{@link MyServiceResponse }{@code >}}
     *
     */
    @XmlElementDecl(namespace = "http://www.example.com/type", name = "serviceResponse")
    public JAXBElement<MyServiceResponse> createServiceResponse(MyServiceResponse value) {
        return new JAXBElement<MyServiceResponse>(_ServiceResponse_QNAME, MyServiceResponse.class, null, value);
    }

}

Answer 1

You can set elementFormDefault="qualified" for your model by creating a package-info.java and adding: 您可以通过创建package-info.java并添加以下内容来为模型设置elementFormDefault =“ qualified” ：

package-info.java package-info.java

@XmlSchema(namespace="http://www.example.com/type", elementFormDefault=XmlNsForm.QUALIFIED)

package mypkg;

import javax.xml.bind.annotation.*;

This will allow your regular XML, but not your "stripped" XML, to work. 这将允许您的常规XML，而不是“剥离的” XML，可以工作。 The difference between the two, besides the "stripping" of the outer, wrapper elements, is the fact that your original XML has a default namespace set, while the stripped XML does not. 除了外部包装元素的“剥离”之外，两者之间的区别在于原始XML具有默认名称空间集，而剥离的XML没有。

Answer 2

Set the name attribute on the @XmlType annotation: 在@XmlType批注上设置name属性：

@XmlType(name = "Body", propOrder = {

})
public static class Body { ... }

and 和

@XmlType(name = "Car", propOrder = {

})
public static class Car { ... }

从XmlStreamReader解组JAXB会导致空对象

问题描述

2 个解决方案

解决方案1
1 已采纳 2017-03-28 14:56:45

解决方案2
1 2017-03-28 15:08:05

从XmlStreamReader解组JAXB会导致空对象

问题描述

2 个解决方案

解决方案1 1 已采纳 2017-03-28 14:56:45

解决方案2 1 2017-03-28 15:08:05

解决方案1
1 已采纳 2017-03-28 14:56:45

解决方案2
1 2017-03-28 15:08:05