Xamarin Android:在strings.xml中保存Facebook Access Token

Question

我在google上搜索了如何动态编辑Resources.Values.strings.xml文件,这样我就可以添加我的Facebook Access Token,这样用户在重用应用程序时就不需要再次登录了.是否可以编辑它,或者我是否必须使用其他方法来存储令牌？

Answer 1

我认为最好的地方就是把它保存到KeyStore.为此,您必须在此处使用DependencyService 更多信息

接口和实现将是:

PCL界面

public interface IAuth
{
    void CreateStore();
    IEnumerable<string> FindAccountsForService(string serviceId);
    void Save(string pin,string serviceId);
    void Delete(string serviceId);
}

Android的

public class IAuthImplementation : IAuth
{
    Context context;
    KeyStore ks;
    KeyStore.PasswordProtection prot;

    static readonly object fileLock = new object();

    const string FileName = "MyProg.Accounts";
    static readonly char[] Password = null;

    public void CreateStore()
    {

        this.context = Android.App.Application.Context;

        ks = KeyStore.GetInstance(KeyStore.DefaultType);

        prot = new KeyStore.PasswordProtection(Password);

        try
        {
            lock (fileLock)
            {
                using (var s = context.OpenFileInput(FileName))
                {
                    ks.Load(s, Password);
                }
            }
        }
        catch (Java.IO.FileNotFoundException)
        {
            //ks.Load (null, Password);
            LoadEmptyKeyStore(Password);
        }
    }

    public IEnumerable<string> FindAccountsForService(string serviceId)
    {
        var r = new List<string>();

        var postfix = "-" + serviceId;

        var aliases = ks.Aliases();
        while (aliases.HasMoreElements)
        {
            var alias = aliases.NextElement().ToString();
            if (alias.EndsWith(postfix))
            {
                var e = ks.GetEntry(alias, prot) as KeyStore.SecretKeyEntry;
                if (e != null)
                {
                    var bytes = e.SecretKey.GetEncoded();
                    var password = System.Text.Encoding.UTF8.GetString(bytes);
                    r.Add(password);
                }
            }
        }
        return r;
    }

    public void Delete(string serviceId)
    {
        var alias = MakeAlias(serviceId);

        ks.DeleteEntry(alias);
        Save();
    }

    public void Save(string pin, string serviceId)
    {
        var alias = MakeAlias(serviceId);

        var secretKey = new SecretAccount(pin);
        var entry = new KeyStore.SecretKeyEntry(secretKey);
        ks.SetEntry(alias, entry, prot);

        Save();
    }

    void Save()
    {
        lock (fileLock)
        {
            using (var s = context.OpenFileOutput(FileName, FileCreationMode.Private))
            {
                ks.Store(s, Password);
            }
        }
    }

    static string MakeAlias(string serviceId)
    {
        return "-" + serviceId;
    }

    class SecretAccount : Java.Lang.Object, ISecretKey
    {
        byte[] bytes;
        public SecretAccount(string password)
        {
            bytes = System.Text.Encoding.UTF8.GetBytes(password);
        }
        public byte[] GetEncoded()
        {
            return bytes;
        }
        public string Algorithm
        {
            get
            {
                return "RAW";
            }
        }
        public string Format
        {
            get
            {
                return "RAW";
            }
        }
    }

    static IntPtr id_load_Ljava_io_InputStream_arrayC;

    void LoadEmptyKeyStore(char[] password)
    {
        if (id_load_Ljava_io_InputStream_arrayC == IntPtr.Zero)
        {
            id_load_Ljava_io_InputStream_arrayC = JNIEnv.GetMethodID(ks.Class.Handle, "load", "(Ljava/io/InputStream;[C)V");
        }
        IntPtr intPtr = IntPtr.Zero;
        IntPtr intPtr2 = JNIEnv.NewArray(password);
        JNIEnv.CallVoidMethod(ks.Handle, id_load_Ljava_io_InputStream_arrayC, new JValue[]
            {
                new JValue (intPtr),
                new JValue (intPtr2)
            });
        JNIEnv.DeleteLocalRef(intPtr);
        if (password != null)
        {
            JNIEnv.CopyArray(intPtr2, password);
            JNIEnv.DeleteLocalRef(intPtr2);
        }
    }

首先在Android应用程序的主要活动中调用Create Store. - 这可以通过检查保存和删除中的ks == null并调用方法(如果为true)来改进并从接口中删除CreateStrore()

然后,这会将访问令牌保存到KeyStore您稍后可以检索的权限