import com.sun.xml.internal.ws.api.policy.ModelGenerator; //导入依赖的package包/类
/**
 * Adds a PolicyReference element that points to the policy of the element,
 * if the policy does not have any id or name. Writes policy inside the element otherwise.
 *
 * @param subject
 *      PolicySubject to be referenced or marshalled
 * @param writer
 *      A TXW on to which we shall add the PolicyReference
 */
private void writePolicyOrReferenceIt(final PolicySubject subject, final TypedXmlWriter writer) {
    final Policy policy;
    try {
        policy = subject.getEffectivePolicy(merger);
    } catch (PolicyException e) {
        throw LOGGER.logSevereException(new WebServiceException(PolicyMessages.WSP_1011_FAILED_TO_RETRIEVE_EFFECTIVE_POLICY_FOR_SUBJECT(subject.toString()), e));
    }
    if (policy != null) {
        if (null == policy.getIdOrName()) {
            final PolicyModelGenerator generator = ModelGenerator.getGenerator();
            try {
                final PolicySourceModel policyInfoset = generator.translate(policy);
                marshaller.marshal(policyInfoset, writer);
            } catch (PolicyException pe) {
                throw LOGGER.logSevereException(new WebServiceException(PolicyMessages.WSP_1002_UNABLE_TO_MARSHALL_POLICY_OR_POLICY_REFERENCE(), pe));
            }
        } else {
            final TypedXmlWriter policyReference = writer._element(policy.getNamespaceVersion().asQName(XmlToken.PolicyReference), TypedXmlWriter.class);
            policyReference._attribute(XmlToken.Uri.toString(), '#' + policy.getIdOrName());
        }
    }
}