我今天一直在尝试使用WP7应用程序并且已经打了一针墙.
我喜欢在用户界面和主应用程序代码之间进行分离,但我已经碰壁了.
我喜欢在用户界面和主应用程序代码之间进行分离,但我已经碰壁了.
我已经成功实现了webclient请求并获得了结果,但由于调用是异步的,我不知道如何将此备份传递到UI级别.我似乎无法等待对完成或任何事情的回应.
我一定做错了什么.
(这是我在我的网站上下载的xBox360Voice库：http://www.jamesstuddart.co.uk/Projects/ASP.Net/Xbox_Feeds/,我将其作为测试移植到WP7)
这是后端代码片段：
internal const string BaseUrlFormat = "http://www.360voice.com/api/gamertag-profile.asp?tag={0}";
internal static string ResponseXml { get; set; }
internal static WebClient Client = new WebClient();
public static XBoxGamer? GetGamer(string gamerTag)
{
var url = string.Format(BaseUrlFormat,gamerTag);
var response = GetResponse(url,null,null);
return SerializeResponse(response);
}
internal static XBoxGamer? SerializeResponse(string response)
{
if (string.IsNullOrEmpty(response))
{
return null;
}
var tempGamer = new XBoxGamer();
var gamer = (XBoxGamer)SerializationMethods.Deserialize(tempGamer,response);
return gamer;
}
internal static string GetResponse(string url,string userName,string password)
{
if (!string.IsNullOrEmpty(userName) && !string.IsNullOrEmpty(password))
{
Client.Credentials = new NetworkCredential(userName,password);
}
try
{
Client.DownloadStringCompleted += ClientDownloadStringCompleted;
Client.DownloadStringAsync(new Uri(url));
return ResponseXml;
}
catch (Exception ex)
{
return null;
}
}
internal static void ClientDownloadStringCompleted(object sender,DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
ResponseXml = e.Result;
}
}
这是前端代码：
public void GetGamerDetails()
{
var xBoxManager = XBoxFactory.GetXBoxManager("DarkV1p3r");
var xBoxGamer = xBoxManager.GetGamer();
if (xBoxGamer.HasValue)
{
var profile = xBoxGamer.Value.Profile[0];
imgAvatar.source = new BitmapImage(new Uri(profile.ProfilePictureMiniUrl));
txtUserName.Text = profile.GamerTag;
txtGamerscore.Text = int.Parse(profile.Gamerscore).ToString("G 0,000");
txtZone.Text = profile.PlayerZone;
}
else
{
txtUserName.Text = "Failed to load data";
}
}
现在我明白我需要在ClientDownloadStringCompleted中放置一些内容,但我不确定是什么.
您遇到的问题是,只要在代码路径中引入异步操作,整个代码路径就需要变为异步.
>因为GetResponse调用DownloadStringAsync它必须变为异步,它不能返回一个字符串,它只能在回调时执行
>因为GetGamer调用现在异步的GetResponse,它不能返回XBoxGamer,它只能在回调时执行此操作
>因为GetGamerDetails调用现在异步的GetGamer,它不能在调用后继续使用它的代码,它只能在收到GetGamer的回调后才能继续执行.
>因为GetGamerDetails现在是异步的任何调用它也必须承认这种行为.
> ….这一直持续到用户事件发生的链顶部.
这里有一些空气代码可以解释代码中的某些异步性.
public static void GetGamer(string gamerTag,Action<XBoxGamer?> completed)
{
var url = string.Format(BaseUrlFormat,gamerTag);
var response = GetResponse(url,(response) =>
{
completed(SerializeResponse(response));
});
}
internal static string GetResponse(string url,string password,Action<string> completed)
{
WebClient client = new WebClient();
if (!string.IsNullOrEmpty(userName) && !string.IsNullOrEmpty(password))
{
client.Credentials = new NetworkCredential(userName,password);
}
try
{
client.DownloadStringCompleted += (s,args) =>
{
// Messy error handling needed here,out of scope
completed(args.Result);
};
client.DownloadStringAsync(new Uri(url));
}
catch
{
completed(null);
}
}
public void GetGamerDetails()
{
var xBoxManager = XBoxFactory.GetXBoxManager("DarkV1p3r");
xBoxManager.GetGamer( (xBoxGamer) =>
{
// Need to move to the main UI thread.
dispatcher.BeginInvoke(new Action<XBoxGamer?>(displayGamerDetails),xBoxGamer);
});
}
void displayGamerDetails(XBoxGamer? xBoxGamer)
{
if (xBoxGamer.HasValue)
{
var profile = xBoxGamer.Value.Profile[0];
imgAvatar.source = new BitmapImage(new Uri(profile.ProfilePictureMiniUrl));
txtUserName.Text = profile.GamerTag;
txtGamerscore.Text = int.Parse(profile.Gamerscore).ToString("G 0,000");
txtZone.Text = profile.PlayerZone;
}
else
{
txtUserName.Text = "Failed to load data";
}
}
正如您所看到的,异步编程可能会变得非常混乱.