序列化自定义主体对象

Question

我有一个自定义主体对象，我希望能够对其进行序列化，以便可以将其存储在 FormsAuthentication cookie 的 Userdata 中。我正在尝试使用 DataContractJsonSerializer 来执行此操作，但是当序列化发生时，我只会得到一个空字符串（没有例外）。

[DataContract]
public class MyPrincipal : IPrincipal
{
    private readonly MyIdentity _identity;

    public MyPrincipal(MyIdentity identity)
    {
        _identity = identity;
    }

    [DataMember]
    public IIdentity Identity
    {
        get { return _identity; }
        set { }
    }

    public bool IsInRole(string role)
    {
        return _identity.AuthGroups.Contains(role, StringComparer.OrdinalIgnoreCase);
    }

    public bool IsInRole(string[] roles)
    {
        return roles.Any(IsInRole);
    }
}

[DataContract]
public class MyIdentity : IIdentity
{
    private readonly MyCustomData _customData;

    public MyIdentity(MyCustomData customData)
    {
        _customData = customData;
    }

    #region IIdentity properties

    [DataMember]
    public string Name
    {
        get { return Username; }
        set {}
    }

    [DataMember]
    public string AuthenticationType
    {
        get { return "Forms"; }
        set {}
    }

    [DataMember]
    public bool IsAuthenticated
    {
        get { return true; }
        set { }
    }

    #endregion

    #region custom properties

    [DataMember]
    public string FirstName
    {
        get { return _customData.FirstName; } 
        set { }
    }
    [DataMember]
    public string LastName
    {
        get { return _customData.LastName; }
        set { }
    }
    [DataMember]
    public string RedwoodID
    {
        get { return _customData.CedarnetRedwoodID; }
        set { }
    }
    [DataMember]
    public string Username
    {
        get { return _customData.NetworkLogin; }
        set { }
    }
    [DataMember]
    public string CuwasTicket
    {
        get { return _customData.CuwasTicket; }
        set { }
    }
    [DataMember]
    public List<string> AuthGroups
    {
        get { return _customData.GroupMembership; }
        set { }
    }

    #endregion
}

这是我尝试运行的代码以将其全部序列化：

var serializer = new DataContractJsonSerializer(typeof(MyPrincipal), new List<Type> {typeof(MyPrincipal), typeof(MyIdentity)});
var responseStream = new MemoryStream();
serializer.WriteObject(responseStream, user);
string serializedValue = new StreamReader(responseStream).ReadToEnd();

Answer 1

你漏掉了一行：

serializer.WriteObject(responseStream, user);
responseStream.Position = 0; // This!!
string serializedValue = new StreamReader(responseStream).ReadToEnd();

记住serializer 写入流，StreamReader 从流结束的当前位置开始。

另外，序列化IPrincipal 和IIdentity 看起来不是一件好事。原因是它们代表了一个不稳定的状态，可以随时更改（例如，在序列化后撤销权限）。