根元素和元素参考名称问题的命名空间

2018-06-18 08:00:44

我有几个关于JAXB编组的简单问题。我试图编组包含以下字段的类：

@XmlElementRef(name = "AlternateVerificationKeys", namespace = "http://schemas.microsoft.com/Azure/MediaServices/KeyDelivery/TokenRestrictionTemplate/v1", type = JAXBElement.class, required = false)
protected JAXBElement<ArrayOfTokenVerificationKey> alternateVerificationKeys;

@XmlElement(name = "Audience", required = true, nillable = true)
@XmlSchemaType(name = "anyURI")
protected String audience;

@XmlElement(name = "Issuer", required = true, nillable = true)
@XmlSchemaType(name = "anyURI")
protected String issuer;

@XmlElement(name = "PrimaryVerificationKey", required = true, nillable = true)
protected TokenVerificationKey primaryVerificationKey;

@XmlElementRef(name = "RequiredClaims", namespace = "http://schemas.microsoft.com/Azure/MediaServices/KeyDelivery/TokenRestrictionTemplate/v1", type = JAXBElement.class, required = false)
protected JAXBElement<ArrayOfTokenClaim> requiredClaims;

@XmlElement(name = "TokenType", required = true)
@XmlSchemaType(name = "string")
protected TokenType tokenType;

并简单地使用以下序列化代码：

public static String asString(JAXBContext pContext, Object pObject) throws JAXBException {
    StringWriter sw = new StringWriter();

    Marshaller marshaller = pContext.createMarshaller();
    marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
    marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);
    marshaller.marshal(pObject, sw);

    return sw.toString();
}

我得到的输出是：

<TokenRestrictionTemplate xmlns="http://schemas.microsoft.com/Azure/MediaServices/KeyDelivery/TokenRestrictionTemplate/v1">
    <ArrayOfTokenVerificationKey>
        <TokenVerificationKey
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="SymmetricVerificationKey">
            <KeyValue></KeyValue>
        </TokenVerificationKey>
    </ArrayOfTokenVerificationKey>
    <Audience>urn:test</Audience>
    <Issuer>http://testacs.com/</Issuer>
    <PrimaryVerificationKey
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="SymmetricVerificationKey">
        <KeyValue></KeyValue>
    </PrimaryVerificationKey>
    <ArrayOfTokenClaim>
        <TokenClaim>
            <ClaimType>urn:microsoft:azure:mediaservices:contentkeyidentifier</ClaimType>
            <ClaimValue
                xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true"/>
        </TokenClaim>
    </ArrayOfTokenClaim>
    <TokenType>SWT</TokenType>
</TokenRestrictionTemplate>

现在，这是我面临的问题：

我希望名称空间xmlns：xsi =“http://www.w3.org/2001/XMLSchema-instance”出现在根元素中，即TokenRestrictionTemplate中，而不是单独的子元素。我怎样才能做到这一点？

我有一些元素，例如带有@XmlElementRef（name =“AlternateVerificationKeys”...）的 JAXBElement ，但是当我编组子元素的名称看起来是ArrayOfTokenVerificationKey而不是AlternateVerificationKeys 。我怎样才能解决这个问题？

我希望名称空间xmlns：xsi =“http://www.w3.org/2001/XMLSchema-instance”出现在根元素中，即TokenRestrictionTemplate中，而不是单独的子元素。我怎样才能做到这一点？

这是XML的核心功能。您可以通过使用从第一个继承的抽象类和多个具体类来实现此目的。你也应该使用@XmlTransient和@XmlSeeAlso来注解抽象类，他们接收具体类的列表。下面的例子。

1.用这些注释创建一个名为TokenVerificationKey的抽象类。

@XmlTransient
@XmlSeeAlso({SymmetricVerificationKey.class, X509CertTokenVerificationKey.class})
public abstract class TokenVerificationKey {

}

2. Finnaly，用这些注释来定义具体的类：

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "SymmetricVerificationKey")
public class SymmetricVerificationKey extends TokenVerificationKey {

    @XmlElement(name = "KeyValue")
    private byte[] keyValue;

}

我有一些元素，例如带有@XmlElementRef（name =“AlternateVerificationKeys”...）的JAXBElement，但是当我编组子元素的名称看起来是ArrayOfTokenVerificationKey而不是AlternateVerificationKeys。我怎样才能解决这个问题？

您应该使用@XmlElementWrapper注释TokenRestrictionTemplate.alternateVerificationKeys以创建集合（包装器）元素和@XmlElement以设置子元素名称：

@XmlElementWrapper(name = "AlternateVerificationKeys")
@XmlElement(name = "TokenVerificationKey")
private List<TokenVerificationKey> alternateVerificationKeys;

这个设置与前一个设置相结合，产生如下输出。

有了这个技巧，你会得到这个输出：

<TokenRestrictionTemplate xmlns="http://schemas.microsoft.com/Azure/MediaServices/KeyDelivery/TokenRestrictionTemplate/v1" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
    <AlternateVerificationKeys>
        <TokenVerificationKey i:type="SymmetricVerificationKey">
            <KeyValue>cGVwZXBlZGtkZGllZGpkamRqZGplaWRqZWVpZGplaWRqaWpkZWltZGVpbWRlaWRpZWQ=</KeyValue>
        </TokenVerificationKey>
        <TokenVerificationKey i:type="X509CertTokenVerificationKey">
            <RawBody>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</RawBody>
        </TokenVerificationKey>
    </AlternateVerificationKeys>
    <Audience>http://audience.com</Audience>
    <Issuer>https://issuer.com</Issuer>
    <PrimaryVerificationKey i:type="SymmetricVerificationKey">
        <KeyValue>cGVwZXBlZGtkZGllZGpkamRqZGplaWRqZWVpZGplaWRqaWpkZWltZGVpbWRlaWRpZWQ=</KeyValue>
    </PrimaryVerificationKey>
    <RequiredClaims>
        <TokenClaim>
            <ClaimType>urn:microsoft:azure:mediaservices:contentkeyidentifier</ClaimType>
            <ClaimValue i:nil="true"/>
        </TokenClaim>
    </RequiredClaims>
    <TokenType>SWT</TokenType>
</TokenRestrictionTemplate>

附加信息：

您可能希望在XML的开头定义一次名称空间。你应该定义"com.sun.xml.bind.namespacePrefixMapper" propery。您还可以设置命名空间的首选前缀。

btw：用于.NET的Azure SDK使用“i”作为前缀。

    Marshaller m = context.createMarshaller();
    m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
    m.setProperty("com.sun.xml.bind.namespacePrefixMapper", new    NamespacePrefixMapper() {
        @Override
        public String[] getPreDeclaredNamespaceUris() {
            return new String[] {
                    // "http://www.w3.org/2001/XMLSchema-instance"
                    XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI
                    };
        }

        @Override
        public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
            // "http://www.w3.org/2001/XMLSchema-instance"
            if (namespaceUri.equals(XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI)) {
                return "i";
            }
            return suggestion;
        }
    });

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