jaxb - xs :int unmarshalled to null for decimal values

Question

我遇到了一个与基于 JAX-WS 的 WebService 中的解码过程相关的问题。在 WSDL 文件中有一个元素定义为

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

在相关的JAVA类中定义为:

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

当此元素的 XML 值是十进制数 (3.4) 的表示形式时，该元素将被解码为空整数。不会生成 SOAPFault，并且无法区分 WebService 中的十进制值和空值。
可能是 JAXB 实现中的缺陷还是我做错了什么？

Answer 1

Could it be a defect in JAXB implementation or I'm doing something wrong?

这不是 JAXB (JSR-222) 中的缺陷执行。这是 JAX-WS 被配置为使用 JAXB 的结果。下面我将通过一个例子来演示。

根

下面是一个域对象，其字段与您的问题中的字段相匹配。我已经删除了 type=Integer.class来自 @XmlElement注释，因为它是多余的。

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 提供了设置 ValidationEventHandler 的能力。在 Unmarshaller让您可以控制如何处理解码错误。

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很常见，并且每次遇到这种情况时 JAXB 都不应该失败，但是您可以看到 ValidationEvent被提出。

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表明我们不希望继续 unmarshal当 ValidationEvent提出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