Question

我有按钮来附加文件

private void ImgAttach_Click(object sender, EventArgs e)
        {
            var _Intent = new Intent();
            _Intent.SetType("*/*");
            _Intent.SetAction(Intent.ActionGetContent);
            StartActivityForResult(Intent.CreateChooser(_Intent, "Select File"), 0);
        }

选择文件后，如果是图像，我可以获得真实路径。如果它不是图像（PDF，DOCX），则不起作用！例如，以下是选择图像后返回的路径：

"/storage/0403-0201/Pictures/beach_huts.jpg"

但选择文件后，会出现此错误

Android.Database.CursorIndexOutOfBoundsException：请求索引0，大小为0

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
            base.OnActivityResult(requestCode, resultCode, data);

            if (resultCode == Result.Ok)
            {
                Android.Net.Uri selectedUri = data.Data;
                ////////////////////////
                string s = GetRealPathFromURI(selectedUri);
            }
}

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

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

            return path;
        }

Answer 1

这是答案

/**
 * Get a file path from a Uri. This will get the the path for Storage Access
 * Framework Documents, as well as the _data field for the MediaStore and
 * other file-based ContentProviders.
 *
 * @param context The context.
 * @param uri The Uri to query.
 * @author paulburke
 */
        public static string GetRealPathFromURI(Context context,Android.Net.Uri uri)
        {

            bool isKitKat = Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.Kitkat;

            // DocumentProvider
            if (isKitKat && Android.Provider.DocumentsContract.IsDocumentUri(context, uri))
            {
                // ExternalStorageProvider
                if (isExternalStorageDocument(uri))
                {
                    string docId = Android.Provider.DocumentsContract.GetDocumentId(uri);
                    string[] split = docId.Split(':');
                    string type = split[0];

                    if ("primary".Equals(type,StringComparison.OrdinalIgnoreCase))
                    {
                        return Android.OS.Environment.ExternalStorageDirectory + "/" + split[1];
                    }

                    // TODO handle non-primary volumes
                }
                // DownloadsProvider
                else if (isDownloadsDocument(uri))
                {

                    string id = Android.Provider.DocumentsContract.GetDocumentId(uri);
                    Android.Net.Uri contentUri = ContentUris.WithAppendedId(Android.Net.Uri.Parse("content://downloads/public_downloads"), Convert.ToInt64(id));

                    return getDataColumn(context, contentUri, null, null);
                }
                // MediaProvider
                else if (isMediaDocument(uri))
                {
                    string docId = Android.Provider.DocumentsContract.GetDocumentId(uri);
                    string[] split = docId.Split(':');
                    string type = split[0];

                    Android.Net.Uri contentUri = null;
                    if ("image".Equals(type))
                    {
                        contentUri = Android.Provider.MediaStore.Images.Media.ExternalContentUri;
                    }
                    else if ("video".Equals(type))
                    {
                        contentUri = Android.Provider.MediaStore.Video.Media.ExternalContentUri;
                    }
                    else if ("audio".Equals(type))
                    {
                        contentUri = Android.Provider.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 getDataColumn(context, uri, null, null);
            }
            // File
            else if ("file".Equals(uri.Scheme,StringComparison.OrdinalIgnoreCase))
            {
                return uri.Path;
            }

            return null;
        }

        /**
         * Get the value of the data column for this Uri. This is useful for
         * MediaStore Uris, and other file-based ContentProviders.
         *
         * @param context The context.
         * @param uri The Uri to query.
         * @param selection (Optional) Filter used in the query.
         * @param selectionArgs (Optional) Selection arguments used in the query.
         * @return The value of the _data column, which is typically a file path.
         */
        public static String getDataColumn(Context context,Android.Net.Uri uri, String selection,
                String[] selectionArgs)
        {

            Android.Database.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 column_index = cursor.GetColumnIndexOrThrow(column);
                    return cursor.GetString(column_index);
                }
            }
            finally
            {
                if (cursor != null)
                    cursor.Close();
            }
            return null;
        }


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

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

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

Answer 2

通常你会想要检查所选项目的mime类型，但这是处理媒体商店中不的项目的快速黑客：

string GetRealPathFromURI(Android.Net.Uri contentURI)
{
    try
    {
        Android.Database.ICursor cursor = ContentResolver.Query(contentURI, null, null, null, null);
        if (cursor != null)
        {
            cursor.MoveToFirst();
            string documentId = cursor.GetString(0);
            documentId = documentId.Split(':')[1];
            cursor.Close();
            cursor = ContentResolver.Query(Android.Provider.MediaStore.Images.Media.ExternalContentUri,
                                           null,
                                           Android.Provider.MediaStore.Images.Media.InterfaceConsts.Id + " = ? ", new[] { documentId },
                                           null);
            cursor.MoveToFirst();
            string path = cursor.GetString(cursor.GetColumnIndex(Android.Provider.MediaStore.Images.ImageColumns.Data));
            cursor.Close();
            return path;
        }
        return contentURI.Path;
    }
    catch (Android.Database.CursorIndexOutOfBoundsException ex)
    {
        return contentURI.Path;
    }
}

Xamarin：GetRealPathFromURI适用于图像，但不适用于其他文件

2 个答案: