我有以下XML:
<ns2:Person name="John" age="20" />
我想将它解组为从XSD生成的JAXB对象Person。
这是我正在运行的代码:
JAXBContext context = JAXBContext.newInstance(PersoEntity.class);
Unmarshaller um = context.createUnmarshaller();
StringReader sr = new StringReader(xml);
Person p = (Person)um.unmarshal(sr);
令人惊讶的是我得到以下例外:
javax.xml.bind.UnmarshalException
- with linked exception:
[org.xml.sax.SAXParseException: The prefix "ns2" for element "ns2:Person" is not bound.]
我该如何解决?感谢
答案 0 :(得分:6)
获得片段
您当前获取XML片段的方式导致命名空间声明丢失。在您的片段ns2
不再是前缀,您只需要一个带冒号的元素名称(ns2:Person
)。这将导致名称空间感知解析器出现问题。下面的文章可能是您获取XML片段的更好方法:
处理您的使用案例
使用您拥有的XML片段,您可以创建一个XMLFilter
,从XML元素中删除前缀,然后利用JAXB的UnmarshallerHandler
进行解组。
的演示强> 的
package forum11968399;
import java.io.StringReader;
import javax.xml.bind.*;
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.helpers.XMLFilterImpl;
public class Demo {
private static final String xml = "<ns2:Person name='John' age='20' />";
public static void main(String[] args) throws Exception {
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xmlReader = sp.getXMLReader();
XMLFilter xmlFilter = new MyXMLFilter(xmlReader);
JAXBContext context = JAXBContext.newInstance(PersonEntity.class);
Unmarshaller um = context.createUnmarshaller();
UnmarshallerHandler unmarshallerHandler = um.getUnmarshallerHandler();
xmlFilter.setContentHandler(unmarshallerHandler);
StringReader sr = new StringReader(xml);
xmlFilter.parse(new InputSource(sr));
PersonEntity p = (PersonEntity) unmarshallerHandler.getResult();
}
private static class MyXMLFilter extends XMLFilterImpl {
public MyXMLFilter(XMLReader xmlReader) {
super(xmlReader);
}
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
int colonIndex = qName.indexOf(':');
if(colonIndex >= 0) {
qName = qName.substring(colonIndex + 1);
}
uri = XML_NAMESPACE; //to prevent unknown XML element exception, we have to specify the namespace here
super.startElement(uri, localName, qName, attributes);
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
int colonIndex = qName.indexOf(':');
if(colonIndex >= 0) {
qName = qName.substring(colonIndex + 1);
}
super.endElement(uri, localName, qName);
}
}
}
的 PersonEntity 强> 的
package forum11968399;
import javax.xml.bind.annotation.*;
@XmlRootElement(name="Person")
@XmlAccessorType(XmlAccessType.FIELD)
public class PersonEntity {
@XmlAttribute
private String name;
@XmlAttribute
private int age;
}
答案 1 :(得分:1)
最好的办法是将所需元素嵌套在另一个绑定命名空间的元素中。绑定它并不重要,只需将其作为一个有效的XML文档即可解析。然后你可以unmarshal by declared type
JAXBContext context = JAXBContext.newInstance(Person.class);
Unmarshaller um = context.createUnmarshaller();
String xml = "<ns2:Person name=\"John\" age=\"20\" />";
String xmlWithPrefixMapped = "<ns2:FakeElement xmlns:ns2=\"someuri\">" + xml + "</ns2:FakeElement>";
StringReader sr = new StringReader(xmlWithPrefixMapped);
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(new InputSource(sr));
Node n = (Node) doc.getDocumentElement().getFirstChild();
JAXBElement<Person> personElement = um.unmarshal(n, Person.class);
Person p = personElement.getValue();