import org.opensaml.saml.saml2.core.NameIDPolicy; //导入依赖的package包/类
@SuppressWarnings("unchecked")
protected final AuthnRequest buildAuthnRequest(final SAML2MessageContext context,
                                               final AssertionConsumerService assertionConsumerService, final SingleSignOnService ssoService) {

    final SAMLObjectBuilder<AuthnRequest> builder = (SAMLObjectBuilder<AuthnRequest>) this.builderFactory
            .getBuilder(AuthnRequest.DEFAULT_ELEMENT_NAME);
    final AuthnRequest request = builder.buildObject();
    if (comparisonType != null) {
        final RequestedAuthnContext authnContext = new RequestedAuthnContextBuilder().buildObject();
        authnContext.setComparison(comparisonType);

        if (authnContextClassRef != null) {
            final AuthnContextClassRef classRef = new AuthnContextClassRefBuilder().buildObject();
            classRef.setAuthnContextClassRef(authnContextClassRef);
            authnContext.getAuthnContextClassRefs().add(classRef);
        }
        request.setRequestedAuthnContext(authnContext);
    }

    final SAMLSelfEntityContext selfContext = context.getSAMLSelfEntityContext();

    request.setID(generateID());
    request.setIssuer(getIssuer(selfContext.getEntityId()));
    request.setIssueInstant(DateTime.now().plusSeconds(this.issueInstantSkewSeconds));
    request.setVersion(SAMLVersion.VERSION_20);
    request.setIsPassive(false);
    request.setForceAuthn(this.forceAuth);
    request.setProviderName("pac4j-saml");

    if (nameIdPolicyFormat != null) {
        final NameIDPolicy nameIdPolicy = new NameIDPolicyBuilder().buildObject();
        nameIdPolicy.setAllowCreate(true);
        nameIdPolicy.setFormat(nameIdPolicyFormat);
        request.setNameIDPolicy(nameIdPolicy);
    }

    request.setDestination(ssoService.getLocation());
    request.setAssertionConsumerServiceURL(assertionConsumerService.getLocation());
    request.setProtocolBinding(assertionConsumerService.getBinding());
    return request;
}