Question

我正在尝试使用Moxy的XML元数据扩展来映射以下界面。但是当我尝试加载它时，我收到以下错误。我无法将公共构造函数添加到AddressType，因为它是枚举。

我的问题是：即使我没有在xml元数据中指定，为什么Moxy会查看AddressType？

public interface TokenizedUnitedStatesAddress
{
    class AddressType extends Enum
    {
        public static final AddressType STREET = new AddressType("street");    
        public static final AddressType PO_BOX = new AddressType("poBox");    
        public static final AddressType RURAL_ROUTE = new AddressType("ruralRoute");

        public static AddressType getEnum(final String type)
        {
            return (AddressType) getEnum(AddressType.class, type);
        }

        protected AddressType(final String name)
        {
            super(name);
        }
    }

    String getApartmentNumber();

    //removed other getters for brevity
}

<xml-bindings xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.eclipse.org/eclipselink/xsds/persistence/oxm http://www.eclipse.org/eclipselink/xsds/eclipselink_oxm_2_4.xsd"
   version="2.4" package-name="com.abc.ic.domain.country.us">
   <java-types>
      <java-type name="TokenizedUnitedStatesAddress">
         <xml-root-element />
         <xml-type
            prop-order="StreetPreDirection StreetNumber StreetName StreetType StreetPostDirection UnitDesignator UnitNumber AddressLine1 AddressLine2 City State PostalCode CarrierRoute LengthAtAddress OwnershipStatus" />
         <java-attributes>
            <xml-element name="StreetPreDirection" java-attribute="preDirectional" />
            <xml-element name="StreetNumber" java-attribute="houseNumber" />
            <xml-element name="StreetName" java-attribute="streetName" />
            <xml-element name="StreetType" java-attribute="streetType" />
            <xml-element name="StreetPostDirection" java-attribute="postDirection" />
            <xml-element name="UnitNumber" java-attribute="apartmentNumber" />
            <xml-element name="AddressLine1" java-attribute="primaryAddress" />
            <xml-element name="AddressLine2" java-attribute="secondaryAddress" />
            <xml-element name="City" java-attribute="cityName" />
            <xml-element name="State" java-attribute="stateAbbreviation" />
            <xml-element name="PostalCode" java-attribute="zipCode" />
         </java-attributes>
      </java-type>
   </java-types>
</xml-bindings>

javax.xml.bind.JAXBException: 
Exception Description: The class com.abc.ic.domain.country.us.TokenizedUnitedStatesAddress$AddressType requires a zero argument constructor or a specified factory method.  Note that non-static inner classes do not have zero argument constructors and are not supported.
 - with linked exception:
[Exception [EclipseLink-50001] (Eclipse Persistence Services - 2.4.0.v20120608-r11652): org.eclipse.persistence.exceptions.JAXBException
Exception Description: The class com.abc.ic.domain.country.us.TokenizedUnitedStatesAddress$AddressType requires a zero argument constructor or a specified factory method.  Note that non-static inner classes do not have zero argument constructors and are not supported.]
    at org.eclipse.persistence.jaxb.JAXBContext$TypeMappingInfoInput.createContextState(JAXBContext.java:908)
    at org.eclipse.persistence.jaxb.JAXBContext.<init>(JAXBContext.java:157)
    at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:170)
    at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:157)
    at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:117)
    at org.eclipse.persistence.jaxb.JAXBContextFactory.createContext(JAXBContextFactory.java:107)

Answer 1

即使使用XML来提供元数据，Mxoy impl仍会对该类进行内省。这是因为，根据设计，外部映射文件用于增加注释提供的元数据。

然而问题是，commons-land Enum抽象要求我们为枚举设置一个非公共的单个参数构造函数。我通过添加一个初始化默认枚举的公共no-arg构造函数来修复此问题。这对我的申请来说已经足够了。然而，我创建了一个可以遵循here的错误。

注意：我还查看了foctory-method option of Moxy，但它需要一个空的arg方法作为工厂方法，而不是Enum的情况。

Answer 2

我是EclipseLink MOXy团队的开发人员，我一直在研究这个问题。你是否正确地考虑了AddressType类的原因是正确的，我发现你有一个解决方法。

另一种解决方案是创建一个可以在Apache Enum类及其XML（字符串）表示形式之间进行转换的XmlAdapter，如下所示：

import javax.xml.bind.annotation.adapters.XmlAdapter;

import org.apache.commons.lang.enums.Enum;

import enumbindings.TokenizedUnitedStatesAddress.AddressType;

public class ApacheEnumAdapter extends XmlAdapter<String, Enum> {

    public ApacheEnumAdapter() {
    }

    @Override
    public Enum unmarshal(String s) throws Exception {
        return AddressType.getEnum(s);
    }

    @Override
    public String marshal(Enum e) throws Exception {
        if (null == e) {
            return null;
        }
        return e.getName();
    }

}

然后在你的绑定文件中连接适配器，如下所示：

...
<xml-element name="StreetType" java-attribute="streetType">
    <xml-java-type-adapter value="enumbindings.ApacheEnumAdapter" />
</xml-element>
...

就您输入的错误而言，EclipseLink实际上在这种情况下表现正常，我们不对Apache Commons类进行任何特殊处理，因此仍然需要默认的无参数构造函数（或其他一些处理机制）。但是，我会更新您的错误并将其更改为增强请求以支持开箱即用的Apache Enums，我们将对其进行评估。

谢谢，

瑞克

JAXB（Moxy）XML元数据映射问题

2 个答案: