在Silverlight开发基于http协议客户端连接器(二)

上一篇中我们能够通过自己的WebClientEx与web应用进行通讯，这样我们就能像js中使用ajax那样异步的通过xml或json等格式进行数据收发了。

不过每次都让人家new 一个WebClientEx对象，手动传URI不说，还要管理一个共享的CookieContainer就显得笨拙了。

好吧，我们提供Message基类和一个连接器的上下文类WebConnectorContext。

Message中包含一个消息号（MessageId），一个Parameters字典。另外一个CurrentParameterUrlPart属性，该属性会自动将当前的baseurl与parameters进行拼接，过滤无效参数然后返回一个完整的url。对于一个自定义消息可以从Message继承过来，设置一下有效参数即可。

WebConnecorContext对外只提供一个AddMessageToSend方法，在该方法中设置Message和回调即可。

下面是Message，WebConnectorContext代码还有自定义消息类LoginMessage的代码

public class Message
    {
        public static readonly string INVALID_MESSAGE_ID = "INVALID_MESSAGE_ID";
        protected static readonly string _messageId = "messageId";
        public static readonly string UrlParamSeparator = "?";
        public static readonly string ParamsSeparator = "&";
        public static readonly string EqualSeparator = "=";
        public Message()
        {
            init();
        }
        private void init()
        {
            MessageId = INVALID_MESSAGE_ID;
            Parameters = new Dictionary<string, string>();
            AvaliableParameterNames = new List<string>();
        }
        protected string MessageId { get; set; }
        public Dictionary<string, string> Parameters
        {
            get;
            private set;
        }
        protected List<string> AvaliableParameterNames;
        public string CurrentParameterUrlPart
        {
            get
            {
                string strBuilder = UrlParamSeparator;
                strBuilder += _messageId + EqualSeparator + MessageId;
                foreach (var pair in Parameters)
                {
                    if (AvaliableParameterNames.Contains(pair.Key))
                    {
                        strBuilder = strBuilder.AppendParameterToUrl(pair.Key, pair.Value);
                    }
                    else
                    {
                        System.Diagnostics.Debug.WriteLine(string.Format("没有相应消息规则{0},将忽略此参数：", pair.Key));
                    }
                }
                return strBuilder;
            }
        }
    }
    public static class StringExtension
    {
        public static string AppendParameterToUrl(this string s, string key, string value)
        {
            return s + Message.ParamsSeparator
                     + key
                     + Message.EqualSeparator
                     + value;
        }
    }

public class LoginMessage : Message
    {
        public  readonly static string Uid = "178_sig_uid";
        public readonly static string Signtime = "178_sig_time";
        public readonly static string Appid = "178_sig_appId";
        public readonly static string Appversion = "178_sig_v";
        public readonly static string Isaddapp = "178_sig_added";
        public readonly static string Sessionkey = "178_sig_sessionId";
        public readonly static string Friendlist = "178_sig_friends";
        public readonly static string Signsumber = "178_sig_key";
        public LoginMessage()
        {
            init();
        }
        public LoginMessage(PageSignEntity dataEntity)
        {
            init();
            base.Parameters[LoginMessage.Uid] = dataEntity.Id;
            base.Parameters[LoginMessage.Appid] = dataEntity.Appid;
            base.Parameters[LoginMessage.Appversion] = dataEntity.Appversion;
            base.Parameters[LoginMessage.Signtime] = dataEntity.Signtime;
            base.Parameters[LoginMessage.Signsumber] = dataEntity.Signsumber;
            base.Parameters[LoginMessage.Sessionkey] = dataEntity.Sessionkey;
            base.Parameters[LoginMessage.Isaddapp] = dataEntity.Isaddapp;
            base.Parameters[LoginMessage.Friendlist] = dataEntity.Friendlist;
        }
        private void init()
        {
            base.MessageId = "10000";
            //可以用反射少些代码，或用code generater的方式
            base.AvaliableParameterNames.Add(Uid);
            base.AvaliableParameterNames.Add(Signtime);
            base.AvaliableParameterNames.Add(Appid);
            base.AvaliableParameterNames.Add(Appversion);
            base.AvaliableParameterNames.Add(Isaddapp);
            base.AvaliableParameterNames.Add(Sessionkey);
            base.AvaliableParameterNames.Add(Friendlist);
            base.AvaliableParameterNames.Add(Signsumber);
        }
    }

public class WebConnectorContext
    {
        private List<WebClientWrapper> _asyncTasks;
        private string baseAddress;
        public WebConnectorContext(string baseAddress)
        {
            this.baseAddress = baseAddress;
            init();
        }
        private CookieContainer _cookie = new CookieContainer();
        private object _cookieDataLocker = new object();
        public CookieContainer AppCookie
        {
            get
            {
                lock (_cookieDataLocker)
                {
                    return _cookie;
                }
            }
            protected set
            {
                lock (_cookieDataLocker)
                {
                    _cookie = value;
                }
            }
        }
        private void init()
        {
            _asyncTasks = new List<WebClientWrapper>();
        }
        public virtual void AddMessageToSend(Message msg, Action<WebClientWrapper, string> action)
        {
            var task = new WebClientWrapper()
                {
                    Message = msg
                };
            task.DownloadStringCompleted += (s) => OnResultReceived(task, s, action);
            _asyncTasks.Add(task);
            task.SendAsync(baseAddress, AppCookie);
        }
        private void onResultReceived(WebClientWrapper task, string e, Action<WebClientWrapper, string> action)
        {
            if(action != null)
                action(task, e);
            _asyncTasks.Remove(task);
        }
    }