自定义一个叫 ReadOnlyXmlMembershipProvider 的 MembershipProvider，用 XML 作为用户储藏室

1. 配置 web.config

<membership defaultProvider="AspNetReadOnlyXmlMembershipProvider">
  <providers>
    <clear />
    <add name="AspNetReadOnlyXmlMembershipProvider" type="OpenIdWebRingSsoProvider.Code.ReadOnlyXmlMembershipProvider" description="Read-only XML membership provider" xmlFileName="~/App_Data/Users.xml" />
  </providers>
</membership>

2. 

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Configuration.Provider;
using System.Security.Permissions;
using System.Web;
using System.Web.Hosting;
using System.Web.Security;
using System.Xml;

public class ReadOnlyXmlMembershipProvider : MembershipProvider {
    private Dictionary<string, MembershipUser> users;
    private string xmlFileName;

    // MembershipProvider Properties
    public override string ApplicationName {
        get { throw new NotSupportedException(); }
        set { throw new NotSupportedException(); }
    }

    public override bool EnablePasswordRetrieval {
        get { return false; }
    }

    public override bool EnablePasswordReset {
        get { return false; }
    }

    public override int MaxInvalidPasswordAttempts {
        get { throw new NotSupportedException(); }
    }

    public override int MinRequiredNonAlphanumericCharacters {
        get { throw new NotSupportedException(); }
    }

    public override int MinRequiredPasswordLength {
        get { throw new NotSupportedException(); }
    }

    public override int PasswordAttemptWindow {
        get { throw new NotSupportedException(); }
    }

    public override MembershipPasswordFormat PasswordFormat {
        get { throw new NotSupportedException(); }
    }

    public override string PasswordStrengthRegularExpression {
        get { throw new NotSupportedException(); }
    }

    public override bool RequiresQuestionAndAnswer {
        get { throw new NotSupportedException(); }
    }

    public override bool RequiresUniqueEmail {
        get { throw new NotSupportedException(); }
    }

    // MembershipProvider Methods
    public override void Initialize(string name, NameValueCollection config) {
        // Verify that config isn't null
        if (config == null) {
            throw new ArgumentNullException("config");
        }

        // Assign the provider a default name if it doesn't have one
        if (string.IsNullOrEmpty(name)) {
            name = "ReadOnlyXmlMembershipProvider";
        }

        // Add a default "description" attribute to config if the
        // attribute doesn't exist or is empty
        if (string.IsNullOrEmpty(config["description"])) {
            config.Remove("description");
            config.Add("description", "Read-only XML membership provider");
        }

        // Call the base class's Initialize method
        base.Initialize(name, config);

        // Initialize _XmlFileName and make sure the path
        // is app-relative
        string path = config["xmlFileName"];

        if (string.IsNullOrEmpty(path)) {
            path = "~/App_Data/Users.xml";
        }

        if (!VirtualPathUtility.IsAppRelative(path)) {
            throw new ArgumentException("xmlFileName must be app-relative");
        }

        string fullyQualifiedPath = VirtualPathUtility.Combine(
            VirtualPathUtility.AppendTrailingSlash(HttpRuntime.AppDomainAppVirtualPath),
            path);

        this.xmlFileName = HostingEnvironment.MapPath(fullyQualifiedPath);
        config.Remove("xmlFileName");

        // Make sure we have permission to read the XML data source and
        // throw an exception if we don't
        FileIOPermission permission = new FileIOPermission(FileIOPermissionAccess.Read, this.xmlFileName);
        permission.Demand();

        // Throw an exception if unrecognized attributes remain
        if (config.Count > 0) {
            string attr = config.GetKey(0);
            if (!string.IsNullOrEmpty(attr)) {
                throw new ProviderException("Unrecognized attribute: " + attr);
            }
        }
    }

    public override bool ValidateUser(string username, string password) {
        // Validate input parameters
        if (string.IsNullOrEmpty(username) ||
            string.IsNullOrEmpty(password)) {
            return false;
        }

        try {
            // Make sure the data source has been loaded
            this.ReadMembershipDataStore();

            // Validate the user name and password
            MembershipUser user;
            if (this.users.TryGetValue(username, out user)) {
                if (user.Comment == password) { // Case-sensitive
                    // NOTE: A read/write membership provider
                    // would update the user's LastLoginDate here.
                    // A fully featured provider would also fire
                    // an AuditMembershipAuthenticationSuccess
                    // Web event
                    return true;
                }
            }

            // NOTE: A fully featured membership provider would
            // fire an AuditMembershipAuthenticationFailure
            // Web event here
            return false;
        } catch (Exception) {
            return false;
        }
    }

    public override MembershipUser GetUser(string username, bool userIsOnline) {
        // Note: This implementation ignores userIsOnline

        // Validate input parameters
        if (string.IsNullOrEmpty(username)) {
            return null;
        }

        // Make sure the data source has been loaded
        this.ReadMembershipDataStore();

        // Retrieve the user from the data source
        MembershipUser user;
        if (this.users.TryGetValue(username, out user)) {
            return user;
        }

        return null;
    }

    public override MembershipUserCollection GetAllUsers(int pageIndex, int pageSize, out int totalRecords) {
        // Note: This implementation ignores pageIndex and pageSize,
        // and it doesn't sort the MembershipUser objects returned

        // Make sure the data source has been loaded
        this.ReadMembershipDataStore();

        MembershipUserCollection users = new MembershipUserCollection();

        foreach (KeyValuePair<string, MembershipUser> pair in this.users) {
            users.Add(pair.Value);
        }

        totalRecords = users.Count;
        return users;
    }

    public override int GetNumberOfUsersOnline() {
        throw new NotSupportedException();
    }

    public override bool ChangePassword(string username, string oldPassword, string newPassword) {
        throw new NotSupportedException();
    }

    public override bool ChangePasswordQuestionAndAnswer(string username, string password, string newPasswordQuestion, string newPasswordAnswer) {
        throw new NotSupportedException();
    }

    public override MembershipUser CreateUser(string username, string password, string email, string passwordQuestion, string passwordAnswer, bool isApproved, object providerUserKey, out MembershipCreateStatus status) {
        throw new NotSupportedException();
    }

    public override bool DeleteUser(string username, bool deleteAllRelatedData) {
        throw new NotSupportedException();
    }

    public override MembershipUserCollection FindUsersByEmail(string emailToMatch, int pageIndex, int pageSize, out int totalRecords) {
        throw new NotSupportedException();
    }

    public override MembershipUserCollection FindUsersByName(string usernameToMatch, int pageIndex, int pageSize, out int totalRecords) {
        throw new NotSupportedException();
    }

    public override string GetPassword(string username, string answer) {
        throw new NotSupportedException();
    }

    public override MembershipUser GetUser(object providerUserKey, bool userIsOnline) {
        throw new NotSupportedException();
    }

    public override string GetUserNameByEmail(string email) {
        throw new NotSupportedException();
    }

    public override string ResetPassword(string username, string answer) {
        throw new NotSupportedException();
    }

    public override bool UnlockUser(string userName) {
        throw new NotSupportedException();
    }

    public override void UpdateUser(MembershipUser user) {
        throw new NotSupportedException();
    }

    // Helper method
    private void ReadMembershipDataStore() {
        lock (this) {
            if (this.users == null) {
                this.users = new Dictionary<string, MembershipUser>(16, StringComparer.InvariantCultureIgnoreCase);
                XmlDocument doc = new XmlDocument();
                doc.Load(this.xmlFileName);
                XmlNodeList nodes = doc.GetElementsByTagName("User");

                foreach (XmlNode node in nodes) {
                    MembershipUser user = new MembershipUser(
                        Name,                       // Provider name
                        node["UserName"].InnerText, // Username
                        null,                       // providerUserKey
                        null,                       // Email
                        string.Empty,               // passwordQuestion
                        node["Password"].InnerText, // Comment
                        true,                       // isApproved
                        false,                      // isLockedOut
                        DateTime.Now,               // creationDate
                        DateTime.Now,               // lastLoginDate
                        DateTime.Now,               // lastActivityDate
                        DateTime.Now, // lastPasswordChangedDate
                        new DateTime(1980, 1, 1));  // lastLockoutDate

                    this.users.Add(user.UserName, user);
                }
            }
        }
    }
}

3. 

谢谢浏览！