WebAPI 2.x中如何扩展Identity Store

ASP.NET WebAPI 中引入了新的一套身份验证和授权的机制，官方的叫法是ASP.NET Identity，有关这个概念的细节，感兴趣的同学可以参考 http://www.asp.net/identity

这套新的机制，默认还是使用SQL Server来做身份保存的，但更多的是提供了灵活性，包括与外部验证系统（OAuth）的整合。但在一些较为简单的场合下，我们可能希望简化这个部分，例如我们不需要外部整合，而且我们的用户数也相对有限，不希望用数据库来实现。

本文提供了一个实例，我是使用XML文件的方式来保存用户信息的，该文件的格式大致如下

然后，我编写了一个自定义的类型，实现了一些主要的方法

    public class XmlUserStore : IUserStore<ApplicationUser>,IUserPasswordStore<ApplicationUser>,IRoleStore<IdentityRole>
    {

        private string filePath = HttpContext.Current.Server.MapPath("~/app_data/users.xml");


        public Task CreateAsync(ApplicationUser user)
        {
            throw new System.NotImplementedException();
        }

        public Task DeleteAsync(ApplicationUser user)
        {
            throw new System.NotImplementedException();
        }

        public Task<ApplicationUser> FindByIdAsync(string userId)
        {
            return FindByNameAsync(userId);
        }

        public Task<ApplicationUser> FindByNameAsync(string userName)
        {

            var doc = XDocument.Load(filePath);
            var found = doc.Root.Elements("user").FirstOrDefault(x => x.Attribute("name").Value == userName);
            ApplicationUser user = null;
            if (found != null)
            {
                user = new ApplicationUser()
                {
                    UserName = userName,
                    Id = userName,
                    PasswordHash = found.Attribute("password").Value
                };
            }

            return Task<ApplicationUser>.FromResult(user);
        }

        public Task UpdateAsync(ApplicationUser user)
        {
            return Task.FromResult(0);
        }

        public void Dispose()
        {
        }

        public Task<string> GetPasswordHashAsync(ApplicationUser user)
        {
            var result = string.Empty;
            if (user != null)
                result = user.PasswordHash;

            return Task<string>.FromResult(result);
        }

        public Task<bool> HasPasswordAsync(ApplicationUser user)
        {
            throw new System.NotImplementedException();
        }

        public Task SetPasswordHashAsync(ApplicationUser user, string passwordHash)
        {
            var doc = XDocument.Load(filePath);
            var found = doc.Root.Elements("user").FirstOrDefault(x => x.Attribute("name").Value ==user.UserName);

            if(found!=null)
            {
                found.Attribute("password").Value = passwordHash;
                doc.Save(filePath);

                return Task.FromResult(1);
            }

            return Task.FromResult(0);
        }


        public Task CreateAsync(IdentityRole role)
        {
            throw new System.NotImplementedException();
        }

        public Task DeleteAsync(IdentityRole role)
        {
            throw new System.NotImplementedException();
        }

        Task<IdentityRole> IRoleStore<IdentityRole>.FindByIdAsync(string roleId)
        {
            throw new System.NotImplementedException();
        }

        Task<IdentityRole> IRoleStore<IdentityRole>.FindByNameAsync(string roleName)
        {
            throw new System.NotImplementedException();
        }

        public Task UpdateAsync(IdentityRole role)
        {
            throw new System.NotImplementedException();
        }
    }