Question

我想从Uri获取实际路径，当我使用intent选择文件时，它将返回URI，但是下面的代码行不能用于转换URI到字符串路径

打开FilePicker

public static void PickFile(Activity context)
{
    Intent intent = new Intent(Intent.ActionGetContent);
    intent.SetType("*/*");
    context.StartActivityForResult(intent, PICKFILE_RESULT_CODE);
}

获取结果

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
    if(requestCode == PICKFILE_RESULT_CODE)
    {
        string filepath = GetRealPathFromURI(MainActivity.act, data.Data);
    } 
}

public static string GetRealPathFromURI(Activity act, Android.Net.Uri contentURI)
{
    try
    {
        ICursor cursor = act.ContentResolver.Query(contentURI, null, null, null, null);
        cursor.MoveToFirst();
        string documentId = cursor.GetString(0);
        documentId = documentId.Split(':')[1];
        cursor.Close();

        cursor = act.ContentResolver.Query(
        MediaStore.Images.Media.ExternalContentUri,
        null, MediaStore.Images.Media.InterfaceConsts.Id + " = ? ", new[] { documentId }, null);
        cursor.MoveToFirst();
        string path = cursor.GetString(cursor.GetColumnIndex(MediaStore.Images.Media.InterfaceConsts.Data));
        cursor.Close();

        return path;
    }
    catch(Exception e)
    {
        Log.Debug("TAG_DATA",e.ToString());
        return "";
    }
}

错误

System.IndexOutOfRangeException：索引超出了范围阵列。

任何人都可以向我解释，我在这段代码中做错了什么。

Answer 1

如何从Uri xamarin android获取实际路径

我注意到您正在使用MediaStore.Images.Media.ExternalContentUri属性，您想要的是获取Gallery Image的真实路径？

如果您想实现此功能，可以阅读我的回答：Get Path of Gallery Image ?

private string GetRealPathFromURI(Android.Net.Uri uri)
{
    string doc_id = "";
    using (var c1 = ContentResolver.Query(uri, null, null, null, null))
    {
        c1.MoveToFirst();
        string document_id = c1.GetString(0);
        doc_id = document_id.Substring(document_id.LastIndexOf(":") + 1);
    }

    string path = null;

    // The projection contains the columns we want to return in our query.
    string selection = Android.Provider.MediaStore.Images.Media.InterfaceConsts.Id + " =? ";
    using (var cursor = ContentResolver.Query(Android.Provider.MediaStore.Images.Media.ExternalContentUri, null, selection, new string[] { doc_id }, null))
    {
        if (cursor == null) return path;
        var columnIndex = cursor.GetColumnIndexOrThrow(Android.Provider.MediaStore.Images.Media.InterfaceConsts.Data);
        cursor.MoveToFirst();
        path = cursor.GetString(columnIndex);
    }
    return path;
}

更新：

这是一个解决方案：

private string GetActualPathFromFile(Android.Net.Uri uri)
{
    bool isKitKat = Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.Kitkat;

    if (isKitKat && DocumentsContract.IsDocumentUri(this, uri))
    {
        // ExternalStorageProvider
        if (isExternalStorageDocument(uri))
        {
            string docId = DocumentsContract.GetDocumentId(uri);

            char[] chars = { ':' };
            string[] split = docId.Split(chars);
            string type = split[0];

            if ("primary".Equals(type, StringComparison.OrdinalIgnoreCase))
            {
                return Android.OS.Environment.ExternalStorageDirectory + "/" + split[1];
            }
        }
        // DownloadsProvider
        else if (isDownloadsDocument(uri))
        {
            string id = DocumentsContract.GetDocumentId(uri);

            Android.Net.Uri contentUri = ContentUris.WithAppendedId(
                            Android.Net.Uri.Parse("content://downloads/public_downloads"), long.Parse(id));

            //System.Diagnostics.Debug.WriteLine(contentUri.ToString());

            return getDataColumn(this, contentUri, null, null);
        }
        // MediaProvider
        else if (isMediaDocument(uri))
        {
            String docId = DocumentsContract.GetDocumentId(uri);

            char[] chars = { ':' };
            String[] split = docId.Split(chars);

            String type = split[0];

            Android.Net.Uri contentUri = null;
            if ("image".Equals(type))
            {
                contentUri = MediaStore.Images.Media.ExternalContentUri;
            }
            else if ("video".Equals(type))
            {
                contentUri = MediaStore.Video.Media.ExternalContentUri;
            }
            else if ("audio".Equals(type))
            {
                contentUri = MediaStore.Audio.Media.ExternalContentUri;
            }

            String selection = "_id=?";
            String[] selectionArgs = new String[] 
            {
                split[1]
            };

            return getDataColumn(this, contentUri, selection, selectionArgs);
        }
    }
    // MediaStore (and general)
    else if ("content".Equals(uri.Scheme, StringComparison.OrdinalIgnoreCase))
    {

        // Return the remote address
        if (isGooglePhotosUri(uri))
            return uri.LastPathSegment;

        return getDataColumn(this, uri, null, null);
    }
    // File
    else if ("file".Equals(uri.Scheme, StringComparison.OrdinalIgnoreCase))
    {
        return uri.Path;
    }

    return null;
}

public static String getDataColumn(Context context, Android.Net.Uri uri, String selection, String[] selectionArgs)
{
    ICursor cursor = null;
    String column = "_data";
    String[] projection = 
    {
        column
    };

    try
    {
        cursor = context.ContentResolver.Query(uri, projection, selection, selectionArgs, null);
        if (cursor != null && cursor.MoveToFirst())
        {
            int index = cursor.GetColumnIndexOrThrow(column);
            return cursor.GetString(index);
        }
    }
    finally
    {
        if (cursor != null)
            cursor.Close();
    }
    return null;
}

//Whether the Uri authority is ExternalStorageProvider.
public static bool isExternalStorageDocument(Android.Net.Uri uri)
{
    return "com.android.externalstorage.documents".Equals(uri.Authority);
}

//Whether the Uri authority is DownloadsProvider.
public static bool isDownloadsDocument(Android.Net.Uri uri)
{
    return "com.android.providers.downloads.documents".Equals(uri.Authority);
}

//Whether the Uri authority is MediaProvider.
public static bool isMediaDocument(Android.Net.Uri uri)
{
    return "com.android.providers.media.documents".Equals(uri.Authority);
}

//Whether the Uri authority is Google Photos.
public static bool isGooglePhotosUri(Android.Net.Uri uri)
{
    return "com.google.android.apps.photos.content".Equals(uri.Authority);
}

获取OnActivityResult中的实际路径：

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
    base.OnActivityResult(requestCode, resultCode, data);
    if (requestCode == 0)
    {
        var uri = data.Data;
        string path = GetActualPathFromFile(uri);
        System.Diagnostics.Debug.WriteLine("Image path == " + path);

    }
}

Answer 2

阅读本文，您将得到完全简单的答案。

https://commonsware.com/blog/2016/03/15/how-consume-content-uri.html

我的代码如下：

            var targetPath = $"{FileDir}{Path.DirectorySeparatorChar}{FileName}";

            const int bufferSize = 1024;
            using (var inputStream = Activity.ContentResolver.OpenInputStream(audioFileUri))
            {
                using (var outputStream = File.Create(targetPath))
                {
                    var buffer = new byte[bufferSize];
                    while (true)
                    {
                        var count = inputStream.Read(buffer, 0, bufferSize);
                        if (count > 0)
                        {
                            outputStream.Write(buffer, 0, count);
                        }

                        if (count < bufferSize) break;
                    }
                }
            }

Answer 3

以下是Xamarin.Android API 21+的完整解决方案： https://gist.github.com/IlyaLavrov97/a76063a49515764b60d5fba3ebbb2662

其中包括来自专用下载文件夹和Google磁盘的文件更新。

以下解决方案的主要部分：

    /// <summary>
    /// Main feature. Return actual path for file from uri. 
    /// </summary>
    /// <param name="uri">File's uri</param>
    /// <param name="context">Current context</param>
    /// <returns>Actual path</returns>
    private static string GetActualPathForFile(global::Android.Net.Uri uri, Context context)
    {
        bool isKitKat = Build.VERSION.SdkInt >= BuildVersionCodes.Kitkat;

        if (isKitKat && DocumentsContract.IsDocumentUri(context, uri))
        {
            // ExternalStorageProvider
            if (IsExternalStorageDocument(uri))
            {
                string docId = DocumentsContract.GetDocumentId(uri);

                char[] chars = { ':' };
                string[] split = docId.Split(chars);
                string type = split[0];

                if ("primary".Equals(type, StringComparison.OrdinalIgnoreCase))
                    return global::Android.OS.Environment.ExternalStorageDirectory + "/" + split[1];
            }
            // Google Drive
            else if (IsDiskContentUri(uri))
                return GetDriveFileAbsolutePath(context, uri);
            // DownloadsProvider
            else if (IsDownloadsDocument(uri))
            {
                try
                {
                    string id = DocumentsContract.GetDocumentId(uri);

                    if (!TextUtils.IsEmpty(id))
                    {
                        if (id.StartsWith("raw:"))
                            return id.Replace("raw:", "");

                        string[] contentUriPrefixesToTry = new string[]{
                                "content://downloads/public_downloads",
                                "content://downloads/my_downloads",
                                "content://downloads/all_downloads"
                        };

                        string path = null;

                        foreach (string contentUriPrefix in contentUriPrefixesToTry)
                        {
                            global::Android.Net.Uri contentUri = ContentUris.WithAppendedId(
                                    global::Android.Net.Uri.Parse(contentUriPrefix), long.Parse(id));

                            path = GetDataColumn(context, contentUri, null, null);

                            if (!string.IsNullOrEmpty(path))
                                return path;
                        }

                        // path could not be retrieved using ContentResolver, therefore copy file to accessible cache using streams
                        string fileName = GetFileName(context, uri);
                        Java.IO.File cacheDir = GetDocumentCacheDir(context);
                        Java.IO.File file = GenerateFileName(fileName, cacheDir);

                        if (file != null)
                        {
                            path = file.AbsolutePath;
                            SaveFileFromUri(context, uri, path);
                        }

                        // last try
                        if (string.IsNullOrEmpty(path))
                            return global::Android.OS.Environment.ExternalStorageDirectory.ToString() + "/Download/" + GetFileName(context, uri);

                        return path;
                    }
                }
                catch
                {
                    return global::Android.OS.Environment.ExternalStorageDirectory.ToString() + "/Download/" + GetFileName(context, uri);
                }
            }
            // MediaProvider
            else if (IsMediaDocument(uri))
            {
                string docId = DocumentsContract.GetDocumentId(uri);

                char[] chars = { ':' };
                string[] split = docId.Split(chars);

                string type = split[0];

                global::Android.Net.Uri contentUri = null;
                if ("image".Equals(type))
                    contentUri = MediaStore.Images.Media.ExternalContentUri;
                else if ("video".Equals(type))
                    contentUri = MediaStore.Video.Media.ExternalContentUri;
                else if ("audio".Equals(type))
                    contentUri = MediaStore.Audio.Media.ExternalContentUri;

                string selection = "_id=?";
                string[] selectionArgs = new string[] { split[1] };

                return GetDataColumn(context, contentUri, selection, selectionArgs);
            }

        }
        // MediaStore (and general)
        else if ("content".Equals(uri.Scheme, StringComparison.OrdinalIgnoreCase))
        {
            // Return the remote address
            if (IsGooglePhotosUri(uri))
                return uri.LastPathSegment;

            // Google Disk document .legacy
            if (IsDiskLegacyContentUri(uri))
                return GetDriveFileAbsolutePath(context, uri);
            return GetDataColumn(context, uri, null, null);
        }
        // File
        else if ("file".Equals(uri.Scheme, StringComparison.OrdinalIgnoreCase))
            return uri.Path;

        return null;
    }

Answer 4

简而言之，这只是帮助。

public static string GetRealPathFromURI(Activity act, Android.Net.Uri contentURI)
{
    try
    {
        Android.Database.ICursor cursor = act.ContentResolver.Query(contentURI, null, null, null, null);
        cursor.MoveToFirst();
        string documentId = cursor.GetString(0);
        documentId = documentId.Split(':')[1];
        cursor.Close();

        cursor = act.ContentResolver.Query(
        MediaStore.Images.Media.ExternalContentUri,
        null, MediaStore.Images.Media.InterfaceConsts.Id + " = ? ", new[] { documentId }, null);
        cursor.MoveToFirst();
        string path = cursor.GetString(cursor.GetColumnIndex(MediaStore.Images.Media.InterfaceConsts.Data));
        cursor.Close();

        return path;
    }
    catch (Exception e)
    {
        Console.WriteLine(e.ToString());
        return "";
    }
}

如何从Uri xamarin android获取实际路径

4 个答案: