/// <summary>    /// 验证消息的有效性    /// </summary>    /// <param name="context"></param>    /// <returns>如果消息有效，返回true；否则返回false。</returns>    private bool Validate(HttpContext context)    {        string username = RequestEx.TryGetQueryString("username");  //在接口配置的URL中加入了username参数，表示哪个微信公众号        AccountInfo account = AccountInfoCollection.GetAccountInfo(username);        if (account == null)            return false;        string token = account.Token;        string signature = RequestEx.TryGetQueryString("signature");        string timestamp = RequestEx.TryGetQueryString("timestamp");        string nonce = RequestEx.TryGetQueryString("nonce");        if (string.IsNullOrWhiteSpace(signature) || string.IsNullOrWhiteSpace(timestamp) || string.IsNullOrWhiteSpace(nonce))            return false;        return xrwang.weixin.PublicAccount.Utility.CheckSignature(signature, token, timestamp, nonce);    }

RequestBaseMessage bm=helper.Message;switch(bm.MsgType){    case RequestMessageTypeEnum.text:  //文本消息        HandleTextMessage((RequestTextMessage)bm);        break;    case RequestMessageTypeEnum.image: //图片消息        HandleImageMessage((RequestImageMessage)bm);        break;    //处理其他消息    case RequestMessageTypeEnum.event:    //事件        RequestEventMessage ev=(RequestEventMessage)bm;        switch(ev.Event)        {            case RequestEventTypeEnum.subscribe:    //订阅                HandleSubscribeMessage((RequestSubscribeMessage)ev);                break;            case RequestEventTypeEnum.unsubscribe:    //取消订阅                HandleUnsubscribeMessage((RequestUnsubscribeMessage)ev);                break;            //处理其他事件        }        break;    default:        break;}

    /// <summary>    /// 处理微信的POST请求    /// </summary>    /// <param name="context"></param>    /// <returns>返回xml响应</returns>    private string HandlePost(HttpContext context)    {        RequestMessageHelper helper = new RequestMessageHelper(context.Request);        if (helper.Message != null)        {            ResponseBaseMessage responseMessage = HandleRequestMessage(helper.Message);            return responseMessage.ToXml(helper.EncryptType);        }        else            return string.Empty;    }    /// <summary>    /// 处理请求消息，返回响应消息    /// </summary>    /// <returns>返回响应消息</returns>    private ResponseBaseMessage HandleRequestMessage(RequestBaseMessage requestMessage)    {        ResponseTextMessage response = new ResponseTextMessage(requestMessage.FromUserName, requestMessage.ToUserName,             DateTime.Now, string.Format("自动回复，请求内容如下：\r\n{0}", requestMessage));        return response;    }