自定义Proxy 来做 rest wcf的客户端 与 WebChannelFactory<>的bug

[ServiceContract(Name="Profile")]
    public interface IProfile
    {
        [OperationContract]
        [WebGet(UriTemplate = "")]
        ProfileInfo Get();

        [OperationContract]
        [WebInvoke(UriTemplate = "", Method = "PUT")]
        ProfileInfo Update(ProfileInfo instance);

    }

    

        var httpRequest = (HttpWebRequest)WebRequest.Create(url);
            Client.AuthorizeRequest(httpRequest, Authorization.AccessToken);

            WebChannelFactory<IProfile> f = new WebChannelFactory<IProfile>(new Uri(url));
       
            IProfile service = f.CreateChannel();
            IClientChannel clientchanel = service as IClientChannel;
           
            try
            {
                var httpDetails = new HttpRequestMessageProperty();
                httpDetails.Headers[HttpRequestHeader.Authorization] = httpRequest.Headers[HttpRequestHeader.Authorization];
                    ProfileInfo info = new ProfileInfo();
                    info.Name="xxx";
                    var info2 = service.Update(info);
                    var test = service.Get();
                    var info3 = service.Update(info);
                    var test2 =  service.Get();
               
            }

我们可以看到的是 一但我用 Get方法来获取一次数据的话。
Update方法就无法把数据post出去了。很神奇的一个bug.

具体的原因就不清楚了。

为了可以解决这个问题。我们必须自己弄一个Proxy
里面的

Response类是出错时的对象，这样你就可以进行出错的处理了，可以自己抛出异常。跟服务端的Response的属性必须一样
比如说 GetUser()的方法 但是可能因为权限不过，所以要抛出一个xml的消息。这个就必须用到了。

 public class WebShopProxy<T> : RealProxy
    {
        public WebShopProxy(string baseUrl)
            : base(typeof(T))
        {
            BaseUrl = baseUrl;
            
        }

        public AuthorizationState Authorization
        {
            get;
            set;
        }


        private string BaseUrl
        {
            get;
            set;
        }

        private static Dictionary<Type, string> TypeNameCache = new Dictionary<Type, string>();
        private string GetServiceName(Type t)
        {
            if (TypeNameCache.ContainsKey(t))
            {
                return TypeNameCache[t];
            }
            object[] objs = t.GetCustomAttributes(typeof(ServiceContractAttribute), false);
            if (objs !=null && objs.Length>0)
            {
                string name = "";
                ServiceContractAttribute attribute = objs[0] as ServiceContractAttribute;
                if (!string.IsNullOrEmpty(attribute.Name))
                {
                    name = attribute.Name;
                    TypeNameCache.Add(t, name);
                    return name;
                }
                else
                {
                    string msg = string.Format("Type:{0} ServiceContract Attribute does not have name property", t.Name);
                    throw new Exception(msg);
                }
            }
            else
            {
                string msg = string.Format("Type:{0} does not have ServiceContract Attribute", t.Name);
                throw new Exception(msg);
            }
        }

        private WebClient WebClient = new WebClient();
        public override IMessage Invoke(IMessage msg)
        {

            IMethodCallMessage methodCall = msg as IMethodCallMessage;
            byte[] buffer = GetResource(methodCall);
            return ReturnMessage(methodCall, buffer);
        }

        private static IMessage ReturnMessage(IMethodCallMessage methodCall, byte[] buffer)
        {
            try
            {
                if (buffer.Length==0)
                {
                    return new ReturnMessage(null, null, 0, null, methodCall);
                }
                MemoryStream stream = new MemoryStream(buffer);
                var returnType = ((System.Reflection.MethodInfo)(methodCall.MethodBase)).ReturnType;
                DataContractSerializer serizlizer = new DataContractSerializer(returnType);
                object o = serizlizer.ReadObject(stream);
                return new ReturnMessage(o, null, 0, null, methodCall);
            }
            catch (SerializationException)
            {
                DataContractSerializer serizlizer2 = new DataContractSerializer(typeof(Response));
                try
                {
                    MemoryStream stream = new MemoryStream(buffer);
                    var response = (Response)serizlizer2.ReadObject(stream);
                    return new ReturnMessage(new WebShopException(response), methodCall);
                }
                catch (Exception e)
                {
                    return new ReturnMessage(e, methodCall);
                }
            }
        }

        private byte[] GetResource(IMethodCallMessage methodCall)
        {
            WebClient.Headers.Add("Content-Type", "application/xml; charset=utf-8");
            if (Authorization!=null)
            {
                WebClient.Headers["Authorization"] = "oauth token="+Authorization.AccessToken;
            }

            string serviceName = GetServiceName(typeof(T));
            string uritemplate = "";
            string url ="";
            byte[] buffer;
            object[] webGetObjs = methodCall.MethodBase.GetCustomAttributes(typeof(WebGetAttribute), false);
            object[] webInvokeObjs = methodCall.MethodBase.GetCustomAttributes(typeof(WebInvokeAttribute), false);
            if (webGetObjs !=null && webGetObjs.Length>0)
            {
                WebGetAttribute attribute = webGetObjs[0] as WebGetAttribute;
                uritemplate = attribute.UriTemplate.ToLower();
                for (int i=0; i<methodCall.ArgCount; i++)
                {
                    object o = methodCall.GetArg(i);
                    string name =  methodCall.GetArgName(i).ToLower();
                    string replaceName = "{"+name+"}";
                    if (uritemplate.IndexOf(name)!=-1)
                    {
                        if (CheckType(o))
                        {
                            uritemplate = uritemplate.Replace(replaceName, HttpUtility.UrlEncode(o.ToString()));
                        }
                        else
                        {
                            throw new Exception(string.Format("parameter {0} should be int or string type", name));
                        }
                    }
                    else
                    {
                        throw new Exception(string.Format("WebGet Attribute can not support parameter {0}.", name));
                    }
                }
                url = MakeUrl(serviceName, uritemplate, url);
                buffer =  WebClient.DownloadData(url);
            }
            else if (webInvokeObjs !=null && webInvokeObjs.Length>0)
            {
                WebInvokeAttribute attribute =  webInvokeObjs[0] as WebInvokeAttribute;
                uritemplate = attribute.UriTemplate.ToLower();
                StringBuilder postData = new StringBuilder();
                int warper =0;
                for (int i=0; i<methodCall.ArgCount; i++)
                {
                    object o = methodCall.GetArg(i);
                    string name =  methodCall.GetArgName(i).ToLower();
                    string replaceName = "{"+name+"}";
                    if (uritemplate.IndexOf(name)!=-1)
                    {
                        if (CheckType(o))
                        {
                           uritemplate = uritemplate.Replace(replaceName, HttpUtility.UrlEncode(o.ToString()));
                        }
                        else
                        {
                            throw new Exception(string.Format("Parameter {0} should be int or string type.", name));
                        }
                    }
                    else
                    {
                        if (warper>0)
                        {
                            throw new Exception("At most one body parameter can be serialized.");
                        }

                        XmlWriterSettings settings = new XmlWriterSettings();
                        settings.Indent = true;
                        settings.OmitXmlDeclaration = true;
                        settings.NewLineOnAttributes = true;
                      
                        XmlWriter writer = XmlWriter.Create(postData,settings);
                        DataContractSerializer serizlizer = new DataContractSerializer(o.GetType());
                        serizlizer.WriteObject(writer, o);
                        writer.Flush();
                        warper++;
                    }
                }
                url = MakeUrl(serviceName, uritemplate, url);
                byte[] data = Encoding.UTF8.GetBytes(postData.ToString());
                buffer =  WebClient.UploadData(url, attribute.Method, data);
            }
            else
            {
                throw new Exception("You should add webget or webinvoke attribute on this method.");
            }
            return buffer;
        }

        private static bool CheckType(object o)
        {
            return o is int || o is string || o is bool;
        }

        private string MakeUrl(string serviceName, string uritemplate, string url)
        {
            if (uritemplate.StartsWith("/"))
            {
                url = BaseUrl+serviceName+uritemplate;
            }
            else
            {
                url = BaseUrl+serviceName+"/"+ uritemplate;
            }
            return url;
        }
    }

完整的客户端在这边可以下到http://dev.starteenwinkel.nl/doc/DotNetSDK