Xamarin LiteDB UnauthorisedAccessException

Question

我正尝试在Xamarin Forms应用程序中使用LiteDB，但是我似乎无法获得对文件的读写权限。

从我的MainViewModel.cs调用

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我已经给AndroidManifest.xml添加了权限；

<uses-sdk android:minSdkVersion="23" android:targetSdkVersion="25" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
<uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS" />
<uses-permission android:name="android.permission.MANAGE_DOCUMENTS" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_LOGS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.READ_PROFILE" />
<uses-permission android:name="android.permission.READ_USER_DICTIONARY" />
<uses-permission android:name="android.permission.READ_SYNC_SETTINGS" />
<uses-permission android:name="android.permission.READ_SOCIAL_STREAM" />
<uses-permission android:name="android.permission.READ_SYNC_STATS" />
<uses-permission android:name="android.permission.REBOOT" />
<uses-permission android:name="android.permission.RESTART_PACKAGES" />
<uses-permission android:name="android.permission.SET_ORIENTATION" />
<uses-permission android:name="android.permission.SET_DEBUG_APP" />
<uses-permission android:name="android.permission.WRITE_CONTACTS" />
<uses-permission android:name="android.permission.WRITE_PROFILE" />
<uses-permission android:name="android.permission.WRITE_GSERVICES" />
<uses-permission android:name="android.permission.WAKE_LOCK" />

我已经在Android 6.0中为我的应用程序添加了权限；

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更新:我已经检查了路径访问，可以写出文件。

string documentsPath = Android.OS.Environment.ExternalStorageDirectory.AbsolutePath;

var dirPath = documentsPath + "/MyTestFolder";
var exists = Directory.Exists(dirPath);
var filepath = dirPath + "/test.txt";
if (!exists)
{
    Directory.CreateDirectory(dirPath);
    if (!System.IO.File.Exists(filepath))
    {
        var newfile = new Java.IO.File(dirPath, "test.txt");
        using (FileOutputStream outfile = new FileOutputStream(newfile))
        {
            string line = "The very first line!";
            outfile.Write(System.Text.Encoding.ASCII.GetBytes(line));
            outfile.Close();
        }
    }
}

然而，这段代码失败了；

string documentsPath = Android.OS.Environment.ExternalStorageDirectory.AbsolutePath;
var dirPath = documentsPath + "/MyData/MyDB.db";
if (!Directory.Exists(dirPath))
{
    Directory.CreateDirectory(dirPath);
}

using (var db = new LiteDatabase(dirPath))
{
    // Get customer collection
    var collection = db.GetCollection<T>(typeof(T).Name);
    collection.Insert(tobj);
    return true;
}

Answer 1

您需要在Android中使用以下代码来访问、存储/访问您的文件：

var documentsPath = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
var dirPath = Path.Combine(documentsPath, "MyDB.db");

Answer 2

如果我使用存储库模式，一切都很好。

using (var db = new LiteRepository("/storage/emulated/0/MyData/MyDB.db"))
{
    db.Insert(new TestClass {Id = 1});
}

LiteDB存储库模式https://github.com/mbdavid/LiteDB/wiki/LiteRepository