对于十进制值，xs:int解组为null

Question

我遇到了一个与基于JAX-WS的Web服务中的解组过程相关的问题。在WSDL文件中，有一个元素定义为

    <element name="quantity" nillable="true" type="int" />

在相关JAVA类中，它被定义为：

   @XmlElement(name = "Quantity", required = true, type = Integer.class, nillable = true)
   protected Integer quantity;

如果此元素的XML值是十进制数（3.4）的表示形式，则该元素将被解组为空整数。不会生成SOAPFault，并且不可能在WebService中区分十进制值和空值。这可能是JAXB实现中的缺陷还是我做错了什么？

Answer 1

我回答了这个问题：https://stackoverflow.com/a/30617814/3632201

在过去的一周里，我一直在努力解决这个问题，最终我找到了一个有效的解决方案。诀窍在于JAXB在用@XmlRootElement注释的对象中查找beforeUnmarshal和afterUnmarshal方法。

..
@XmlRootElement(name="MSEPObtenerPolizaFechaDTO")
@XmlAccessorType(XmlAccessType.FIELD)

public class MSEPObtenerPolizaFechaDTO implements Serializable {
..

public void beforeUnmarshal(Unmarshaller unmarshaller, Object parent) throws JAXBException, IOException, SAXException {
        unmarshaller.setSchema(Utils.getSchemaFromContext(this.getClass()));
        unmarshaller.setEventHandler(new CustomEventHandler());
  }

  public void afterUnmarshal(Unmarshaller unmarshaller, Object parent) throws JAXBException {
        unmarshaller.setSchema(null);
        unmarshaller.setEventHandler(null);
  }

使用此ValidationEventHandler：

public class CustomEventHandler implements ValidationEventHandler{

      @Override
      public boolean handleEvent(ValidationEvent event) {
            if (event.getSeverity() == event.ERROR ||
                        event.getSeverity() == event.FATAL_ERROR)
            {
                  ValidationEventLocator locator = event.getLocator();
                  throw new RuntimeException(event.getMessage(), event.getLinkedException());
            }
            return true;
      }
}

}

这是在实用程序类中创建的metodh getSchemaFromContext：

  @SuppressWarnings("unchecked")
  public static Schema getSchemaFromContext(Class clazz) throws JAXBException, IOException, SAXException{
        JAXBContext jc = JAXBContext.newInstance(clazz);
        final List<ByteArrayOutputStream> outs = new ArrayList<ByteArrayOutputStream>();
        jc.generateSchema(new SchemaOutputResolver(){
              @Override
              public Result createOutput(String namespaceUri,
                         String suggestedFileName) throws IOException {
              ByteArrayOutputStream out = new ByteArrayOutputStream();
              outs.add(out);
              StreamResult streamResult = new StreamResult(out);
              streamResult.setSystemId("");
              return streamResult;
              }
        });
        StreamSource[] sources = new StreamSource[outs.size()];
        for (int i = 0; i < outs.size(); i++) {
              ByteArrayOutputStream out = outs.get(i);
              sources[i] = new StreamSource(new ByteArrayInputStream(out.toByteArray()), "");
        }
        SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
        return sf.newSchema(sources);
  }

Answer 2

这可能是JAXB实现中的缺陷还是我做错了什么？

这不是JAXB（JSR-222）实现中的缺陷。这是JAX-WS如何配置为使用JAXB的结果。下面我将用一个例子来演示。

根

下面是一个域对象，其字段与您的问题中的字段匹配。我已经删除了type=Integer。从@xmlement注释中初始化，因为它是冗余的。

import javax.xml.bind.annotation.*;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Root {

    @XmlElement(name = "Quantity", required = true, nillable = true)
    protected Integer quantity;

}

演示

JAXB提供了在Unmarshaller上设置ValidationEventHandler的功能，使您能够控制如何处理unmarshal错误。

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

public class Demo {

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

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        unmarshaller.setEventHandler(new ValidationEventHandler() {

            @Override
            public boolean handleEvent(ValidationEvent event) {
                System.out.println(event.getMessage());
                return true;
            }
        });

        StringReader xml = new StringReader("<root><Quantity>3.4</Quantity></root>");
        Root root = (Root) unmarshaller.unmarshal(xml);

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

}

输出

在专家组中，我们决定无效元素数据是常见的，并且JAXB不应该在每次遇到这种情况时都失败，但是您可以看到出现了一个ValidationEvent。

Not a number: 3.4
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
    <Quantity xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true"/>
</root>

更新演示

如果我们更新ValidationEventHandler以表明我们不希望继续散集时，我们可以进行以下更改。

        @Override
        public boolean handleEvent(ValidationEvent event) {
            System.out.println(event.getMessage());
            return false;
        }

更新输出

现在出现以下输出。

Not a number: 3.4
Exception in thread "main" javax.xml.bind.UnmarshalException: Not a number: 3.4
 - with linked exception:
[java.lang.NumberFormatException: Not a number: 3.4]
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleEvent(UnmarshallingContext.java:647)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleError(UnmarshallingContext.java:676)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleError(UnmarshallingContext.java:672)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.Loader.handleParseConversionException(Loader.java:256)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.LeafPropertyLoader.text(LeafPropertyLoader.java:54)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.text(UnmarshallingContext.java:499)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.SAXConnector.processText(SAXConnector.java:166)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.SAXConnector.endElement(SAXConnector.java:139)
    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:606)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1742)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2900)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:607)
    at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:116)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:489)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:835)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:764)
    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:123)
    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1210)
    at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:568)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:203)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:175)
    at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:157)
    at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:214)
    at forum14741140.Demo.main(Demo.java:22)
Caused by: java.lang.NumberFormatException: Not a number: 3.4
    at com.sun.xml.internal.bind.DatatypeConverterImpl._parseInt(DatatypeConverterImpl.java:101)
    at com.sun.xml.internal.bind.v2.model.impl.RuntimeBuiltinLeafInfoImpl$17.parse(RuntimeBuiltinLeafInfoImpl.java:713)
    at com.sun.xml.internal.bind.v2.model.impl.RuntimeBuiltinLeafInfoImpl$17.parse(RuntimeBuiltinLeafInfoImpl.java:711)
    at com.sun.xml.internal.bind.v2.runtime.reflect.TransducedAccessor$CompositeTransducedAccessorImpl.parse(TransducedAccessor.java:232)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.LeafPropertyLoader.text(LeafPropertyLoader.java:50)
    ... 19 more