JAXB Unmarshalling:对象列表

Question

我有

@XmlRootElement(namespace = "http://www.w3.org/2005/Atom", name = "content")
@XmlType(name = "course")
public class Course implements Resource

...

@XmlElementWrapper(name="subcourses")
@XmlElement(name="course")
List<Xlink> subcourses;         //!?

和Xlink类,它在内联变量中工作正常.

public class Xlink
{
    private String href;
    private String value;

    @XmlAttribute(namespace = "http://www.w3.org/1999/xlink")
    public String getHref()
    {
        return href;
    }

    public void setHref(String href)
    {
        this.href = href;
    }

    @XmlValue
    public String getValue()
    {
        return value;
    }

    public void setValue(String value)
    {
        this.value = value;
    }
}

用于XML输入

<atom:content atom:type="xml" xsi:type="course">
...
   <subcourses>
      <course xlink:href="course1">Some course</course>
      <course xlink:href="course2">other course</course>

子主义拒绝被解组(没有任何例外被抛出).

注意:遗憾的是MOXy不是一个选项.

编辑:新的编组对象

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns3:content xmlns:ns2="http://www.w3.org/1999/xlink" xmlns:ns3="http://www.w3.org/2005/Atom">
    <code>SOME CODE</code>
    <name>name</name>
    <subcourses>
        <course ns2:href="Some href">some value</course>
        <course ns2:href="sdsdg">sdfhdfhdhdh</course>
    </subcourses>
</ns3:content>

EDIT2:经过一些实验用解组和编组测试对象我发现我需要的内容相匹配的标头中定义的xmlns命名空间xlink:href=类似xmlns:xlink="http://www.w3.org/1999/xlink"的问题,我从被解析出一个包装类中获取课程元素通过resteasy.因此,结果类不会遗留名称空间信息.

我不知何故需要强迫JAXB理解这xmlns:xlink="http://www.w3.org/1999/xlink"适用于课程元素,但经过一个小时的谷歌我不知所措.

编辑3:我从我的对象

https://github.com/jirutka/atom-jaxb/blob/master/src/main/java/cz/jirutka/atom/jaxb/Entry.java

这是在服务器对应物上使用的.这反过来又是其中的一部分

https://github.com/jirutka/atom-jaxb/blob/master/src/main/java/cz/jirutka/atom/jaxb/Feed.java

我的解组代码的相关部分是:

Feed f = r.readEntity(Feed.class);
out.addAll(unmarshaller.Unmarshal(f.getEntries(), clazz));

这里r是一个javax.ws.rs.core.Response.和unmarshaller

public List<T> Unmarshal(List<Entry> entries, Class clazz)
{
    List<T> out = new ArrayList<T>();
    T instance;
    for (Entry e : entries)
    {
        try
        {
            JAXBContext context = JAXBContext.newInstance(clazz);
            Unmarshaller unmarsh = context.createUnmarshaller();
            instance = (T) unmarsh.unmarshal((Node) e.getContent());

由于这是我第一次使用这项技术,这个代码完全有可能是'wtf'.

Answer 1

当您注释该字段(实例变量)时,请务必加入@XmlAccessorType(XmlAccessType.FIELD)您的课程.

import java.util.List;
import javax.xml.bind.annotation.*;

@XmlRootElement(namespace = "http://www.w3.org/2005/Atom", name = "content")
@XmlAccessorType(XmlAccessType.FIELD)
public class Course implements Resource {

    @XmlElementWrapper(name = "subcourses")
    @XmlElement(name = "course")
    List<Xlink> subcourses;

}

然后确保您的XML输入正确地进行了命名空间限定.您的输入文档应如下所示:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<atom:content xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:atom="http://www.w3.org/2005/Atom">
    <code>SOME CODE</code>
    <name>name</name>
    <subcourses>
        <course xlink:href="Some href">some value</course>
        <course xlink:href="sdsdg">sdfhdfhdhdh</course>
    </subcourses>
</atom:content>

通过我更新的Course类,您的Xlink类和正确的命名空间限定XML文档,以下演示代码对我来说非常有效.

import java.io.File;
import javax.xml.bind.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Course.class);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum17766166/input.xml");
        Course course = (Course) unmarshaller.unmarshal(xml);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(course, System.out);
    }

}

更新#1

Edit2:在对一个测试对象进行解组和编组的一些实验后,我发现我需要在内容的标题中定义xmlns名称空间以匹配xlink:href = like xmlns:xlink ="http://www.w3.org/ 1999/xlink"问题是我从一个由resteasy解析出来的包装类中获取了Course元素.因此,结果类不会遗留名称空间信息.

解决问题的最佳位置是提取您想要解组的片段.以下是您可以使用StAX的策略.

input.xml中

下面是一个示例XML文档,其中命名空间信息定义在您要解组的片段上方.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<foo xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:atom="http://www.w3.org/2005/Atom">
    <bar>
        <atom:content>
            <code>SOME CODE</code>
            <name>name</name>
            <subcourses>
                <course xlink:href="Some href">some value</course>
                <course xlink:href="sdsdg">sdfhdfhdhdh</course>
            </subcourses>
        </atom:content>
    </bar>
</foo>

演示

下面我们将使用StAX XMLStreamReader导航到目标片段.我们将让我们的JAXB实现解组这个片段.这样就可以保留所有命名空间信息.

import javax.xml.bind.*;
import javax.xml.stream.*;
import javax.xml.transform.stream.StreamSource;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Course.class);

        XMLInputFactory xif = XMLInputFactory.newFactory();
        StreamSource source = new StreamSource("src/forum17766166/input.xml");
        XMLStreamReader xsr = xif.createXMLStreamReader(source);
        while(xsr.hasNext()) {
            if(xsr.isStartElement() && "content".equals(xsr.getLocalName())) {
                break;
            }
            xsr.next();
        }

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        Course course = (Course) unmarshaller.unmarshal(xsr);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(course, System.out);
    }

}

产量

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns3:content xmlns:ns2="http://www.w3.org/1999/xlink" xmlns:ns3="http://www.w3.org/2005/Atom">
    <subcourses>
        <course ns2:href="Some href">some value</course>
        <course ns2:href="sdsdg">sdfhdfhdhdh</course>
    </subcourses>
</ns3:content>

更新#2

如果您无法按照UPDATE#1中的描述生成更好的XML片段,则下面是您如何修复当前的XML片段.

NamespaceFilter

您可以使用SAX XMLFilter来修复XML文档.

import org.xml.sax.*;
import org.xml.sax.helpers.*;

public class NamespaceFilter extends XMLFilterImpl {

    private static final String ATOM_URI = "http://www.w3.org/2005/Atom";
    private static final String XLINK_URI = "http://www.w3.org/1999/xlink";

    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes atts) throws SAXException {
        if("atom:content".equals(qName)) {
            super.startElement(ATOM_URI, "content", qName, atts);
        } else if("course".equals(qName))  {
            AttributesImpl modifiedAtts = new AttributesImpl();
            modifiedAtts.addAttribute(XLINK_URI, "href", "xlink:href", null, atts.getValue(0));
            super.startElement(uri, localName, qName, modifiedAtts);
        } else {
            super.startElement(uri, localName, qName, atts);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        if("atom:content".equals(qName)) {
            super.endElement(ATOM_URI, "content", qName);
        } else {
            super.endElement(uri, localName, qName);
        }
    }

}

演示

以下是如何利用XmlFilterJAXB:

import javax.xml.bind.*;
import javax.xml.parsers.*;
import org.xml.sax.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Course.class);

        // Create the XMLFilter
        XMLFilter filter = new NamespaceFilter();

        // Set the parent XMLReader on the XMLFilter
        SAXParserFactory spf = SAXParserFactory.newInstance();
        SAXParser sp = spf.newSAXParser();
        XMLReader xr = sp.getXMLReader();
        filter.setParent(xr);

        // Set UnmarshallerHandler as ContentHandler on XMLFilter
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        UnmarshallerHandler unmarshallerHandler = unmarshaller
                .getUnmarshallerHandler();
        filter.setContentHandler(unmarshallerHandler);

        // Parse the XML
        InputSource xml = new InputSource("src/forum17766166/input.xml");
        filter.parse(xml);
        Course course = (Course) unmarshallerHandler.getResult();

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(course, System.out);
    }

}

欲获得更多信息

• http://blog.bdoughan.com/2012/11/applying-namespace-during-jaxb-unmarshal.html

更新#3

下面是示例代码的简化版本,其中一切正常.也许你的代码中有不同的东西可以帮助你找到.

条目

import javax.xml.bind.annotation.*;

@XmlRootElement(namespace="http://www.w3.org/2005/Atom")
@XmlAccessorType(XmlAccessType.FIELD)
public class Entry<T> {

    @XmlElement(namespace = "http://www.w3.org/2005/Atom")
    @XmlSchemaType(name = "atomInlineOtherContent")
    private T content;

    public T getContent() {
        return content;
    }

}

input.xml中

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<atom:entry xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:atom="http://www.w3.org/2005/Atom">
    <atom:content>
        <code>SOME CODE</code>
        <name>name</name>
        <subcourses>
            <course xlink:href="Some href">some value</course>
            <course xlink:href="sdsdg">sdfhdfhdhdh</course>
        </subcourses>
    </atom:content>
</atom:entry>

演示

import java.io.File;
import javax.xml.bind.*;
import org.w3c.dom.Node;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Entry.class, Course.class);

        // Unmarshal Entry
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum17766166/input.xml");
        Entry entry = (Entry) unmarshaller.unmarshal(xml);

        // Unmarshal Course
        Node contentNode = (Node) entry.getContent();
        Course course = (Course) unmarshaller.unmarshal(contentNode);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(course, System.out);
    }

}

产量

<?xml version="1.0" encoding="UTF-8"?>
<ns0:content xmlns:ns1="http://www.w3.org/1999/xlink" xmlns:ns0="http://www.w3.org/2005/Atom">
   <subcourses>
      <course ns1:href="Some href">some value</course>
      <course ns1:href="sdsdg">sdfhdfhdhdh</course>
   </subcourses>
</ns0:content>