C#-使用Xamarin.Android为Parse.com服务器制作更漂亮的Facebook登录屏幕

概述我正在尝试为Xamarin.Android创建一个登录系统以在解析服务器上使用.我想用Facebook登录该用户,并保存他的真实姓名和小用户照片.我当前显示登录系统的代码是这样的：usingXamarin.Auth;loginFacebookButton.Click+=(sender,e)=>{if(CrossConnecti

我正在尝试为Xamarin.Android创建一个登录系统以在解析服务器上使用.我想用Facebook登录该用户,并保存他的真实姓名和小用户照片.
我当前显示登录系统的代码是这样的：

using Xamarin.Auth;loginFacebookbutton.Click += (sender, e) =>        {            if (CrossConnectivity.Current.IsConnected)                LoginToFacebook();            else            {                displayNoConnectivityMessage();            }        };        loginTwitterbutton.Click += (sender, e) =>        {            LoginToTwitter();        };    }    voID displayNoConnectivityMessage()    {        AlertDialog.Builder alert2 = new AlertDialog.Builder(this);        alert2.Set@R_404_5979@("Network error");        alert2.SetMessage("Connection with the Internet is required. Please check your connectivity and try again.");        alert2.Show();    }    voID displayLoadingMessage(bool dismiss)    {        RunOnUiThread(() =>        {            if (!dismiss)            {                builder = new AlertDialog.Builder(this);                builder.Set@R_404_5979@("Signing in");                builder.SetMessage("Please wait...");                builder.SetCancelable(false);                alert = builder.Create();                alert.Show();            } else {                if (alert != null)                    if (alert.IsShowing)                    {                         alert.dismiss();                        alert.dispose();                    }            }        });    }    async voID LoginToFacebook()    {        var auth = new OAuth2Authenticator(            clIEntID: "809804315805408",            scope: "user_about_me",            authorizeUrl: new Uri("https://m.facebook.com/dialog/oauth/"),            redirectUrl: new Uri("http://www.facebook.com/connect/login_success.HTML")        );        auth.AllowCancel = false;        // If authorization succeeds or is canceled, .Completed will be fired.        auth.Completed += LoginComplete;        var intent = auth.GetUI(this);        StartActivity(intent);    }    public async voID LoginComplete(object sender, AuthenticatorCompletedEventArgs e)    {        string ID = "";        string name = "";        JsonValue obj;        if (!e.IsAuthenticated)        {            var builder = new AlertDialog.Builder(this);            builder.SetMessage("Not Authenticated");            builder.SetPositivebutton("Ok", (o, c) => { });            builder.Create().Show();            return;        }        else {            displayLoadingMessage(false);            AccountStore.Create(this) .Save(e.Account, "Facebook");            // Now that we're logged in, make a OAuth2 request to get the user's info.            var request = new OAuth2Request("GET", new Uri("https://graph.facebook.com/me"), null, e.Account);            await request.GetResponseAsync().ContinueWith(t =>            {                var builder2 = new AlertDialog.Builder(this);                if (t.IsFaulted)                {                    builder2.Set@R_404_5979@("Error");                    builder2.SetMessage(t.Exception.Flatten().InnerException.ToString());                    builder2.Show();                }                else if (t.IsCanceled)                {                    builder2.Set@R_404_5979@("Task Canceled");                    builder2.Show();                }                else {                    obj = JsonValue.Parse(t.Result.GetResponseText());                    ID = obj["ID"];                    name = obj["name"];                }                builder.SetPositivebutton("Ok", (o, c) => { });                builder.Create();            }, UIScheduler);            var accesstoken = e.Account.PropertIEs["access_token"];            var expiresIn = Convert.Todouble(e.Account.PropertIEs["expires_in"]);            var expiryDate = DateTime.Now + TimeSpan.FromSeconds(expiresIn);            var user = await ParseFacebookUtils.LogInAsync(ID, accesstoken, expiryDate);            try            {                user.Add("name", name);            }            catch (Exception ex)            {                Console.Writeline("LoginFragment.cs | LoginComplete() :: user.Add (\"name\",name); :: " + ex.Message);            }            var webClIEnt = new WebClIEnt();            //var httpClIEnt = new httpClIEnt(new NativeMessageHandler());            var url = new Uri("http://graph.facebook.com/" + ID + "/picture?type=small");            application.currentUserImageUrl = url.ToString();            application.currentUsername = name;            byte[] bytes = null;            //bytes = await httpClIEnt.GetByteArrayAsync(url);            bytes = await webClIEnt.DownloadDataTaskAsync(url);            Parsefile saveImagefile = new Parsefile("profileImage.jpg", bytes);            try            {                user.Add("profile_pic", saveImagefile);            }            catch (Exception ex)            {                Console.Writeline("LoginFragment.cs | LoginComplete() :: user.Add (\"profile_pic\",saveImagefile); :: " + ex.Message);            }            application.currentUser = user;            await user.SaveAsync();            displayLoadingMessage(true);            ChangeScreen();        }    }

此代码的问题是这样的：

>登录后,我会显示一条成功消息(简单
白页上的成功消息)必须来自Facebook和
显然,我不愿意在用户身上显示.
>虽然
LoginCompete代码正在运行,应用程序正在后台运行,并且用户看不到任何提示,就像应用程序关闭后
登录再次打开.我试图显示一个AlertDialog与
函数displayNoConnectivityMessage但未显示
在用户什么我不知道的方式.

解决方法:

在Parse上用Facebook登录的最简单方法是将官方的Parse SDK与官方的AndroID SDK版Facebook结合使用以处理单一登录方案.

仅需一些小步骤,即可达到预期的结果：

>按照此小型指南为Facebook SDK设置应用：https://components.xamarin.com/gettingstarted/facebookandroid
>设置解析SDK

public App(){    // App.xaml initialization    ParseClIEnt.Initialize("Your Application ID", "Your .NET Key");    ParseFacebookUtils.Initialize("Your Facebook App ID");    // Other initialization}

>将FB登录按钮添加到视图中.

<com.facebook.login.Widget.Loginbutton  androID:ID="@+ID/login_button"  androID:layout_wIDth="wrap_content"  androID:layout_height="wrap_content"  androID:layout_gravity="center_horizontal"  androID:layout_margintop="30dp"  androID:layout_marginBottom="30dp" />   

>获取回调,并使用令牌通过Parse登录用户.

public class MainActivity : Activity, IFacebookCallback{    protected overrIDe voID OnCreate(Bundle bundle)    {        base.OnCreate(bundle);        // Set our vIEw from the "main" layout resource        // SetContentVIEw (Resource.Layout.Main);        var callbackManager = CallbackManagerFactory.Create();        var loginbutton = FindVIEwByID<Loginbutton>(Resource.ID.login_button);        loginbutton.RegisterCallback(callbackManager, this);    }    #region IFacebookCallback    public voID OnCancel()    {        // Handle Cancel    }    public voID one rror(FacebookException error)    {        // Handle Error    }    public async voID OnSuccess(Object result)    {        // We kNow that this is a LoginResult        var loginResult = (LoginResult) result;        // Convert Java.Util.Date to DateTime        var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);        var expireDate = epoch.AddMilliseconds(loginResult.Accesstoken.Expires.Time);        // FB User Accesstoken        var accesstoken = loginResult.Accesstoken.Token;        ParseUser user = await ParseFacebookUtils.LogInAsync("Your Facebook App ID", accesstoken, expireDate);    }    #endregion... }

>(可选)与Facebook SDK& ParseUser

// You can simply pass the acquired Accesstoken to the GraphRequestvar parameters = new Bundle();parameters.PutString("fIElds", "ID,email,gender,cover,picture.type(small)");var request = new GraphRequest(loginResult.Accesstoken, "me", parameters, httpMethod.Get);// Execute request and Handle response (See FB AndroID SDK GuIDe)// to get image as byte[] from GraphResponsebyte[] data;// Store the image into the ParseUseruser["image"] = new Parsefile("image.jpg", data);

Instead of using the GraphRequest you can always fallback to the httpClIEnt / WebClIEnt and pass the Accesstoken as URL parameter. 07002

额外

这里是官方文档的链接：http://parseplatform.github.io/docs/dotnet/guide/#facebook-users

从Nuget选择SDK：https://www.nuget.org/packages/Xamarin.Facebook.Android/

Xamarin Facebook AndroID SDK的工作方式类似于Java SDK,因此,该文档也值得一看：https://developers.facebook.com/docs/facebook-login/android#addbutton

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