嘗試從字符串路徑解析 Uri 時為空

Question

我正在使用這個FileUtils類來處理Uri ：

public class FileUtils {
private FileUtils() {
}

private static final String TAG = "FileUtils";
private static final boolean DEBUG = false;

private static boolean isExternalStorageDocument(Uri uri) {
    return "com.android.externalstorage.documents".equals(uri.getAuthority());
}

private static boolean isDownloadsDocument(Uri uri) {
    return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}

private static boolean isMediaDocument(Uri uri) {
    return "com.android.providers.media.documents".equals(uri.getAuthority());
}


private static boolean isGooglePhotosUri(Uri uri) {
    return "com.google.android.apps.photos.content".equals(uri.getAuthority());
}

private static String getDataColumn(Context context, Uri uri, String selection,
                                    String[] selectionArgs) {

    Cursor cursor = null;
    final String column = "_data";
    final String[] projection = {
            column
    };

    try {
        cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
                null);
        if (cursor != null && cursor.moveToFirst()) {
            if (DEBUG)
                DatabaseUtils.dumpCursor(cursor);

            final int column_index = cursor.getColumnIndexOrThrow(column);
            return cursor.getString(column_index);
        }
    } finally {
        if (cursor != null)
            cursor.close();
    }
    return null;
}

@RequiresApi(api = Build.VERSION_CODES.KITKAT)
public static String getPath(final Context context, final Uri uri) {

    if (DEBUG)
        Log.d(TAG + " File -",
                "Authority: " + uri.getAuthority() +
                        ", Fragment: " + uri.getFragment() +
                        ", Port: " + uri.getPort() +
                        ", Query: " + uri.getQuery() +
                        ", Scheme: " + uri.getScheme() +
                        ", Host: " + uri.getHost() +
                        ", Segments: " + uri.getPathSegments().toString()
        );

    final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

    // DocumentProvider
    if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
        if (isExternalStorageDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            if ("primary".equalsIgnoreCase(type)) {
                return Environment.getExternalStorageDirectory() + "/" + split[1];
            }

        }
        // DownloadsProvider
        else if (isDownloadsDocument(uri)) {

            final String id = DocumentsContract.getDocumentId(uri);
            final Uri contentUri = ContentUris.withAppendedId(
                    Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

            return getDataColumn(context, contentUri, null, null);
        }
        // MediaProvider
        else if (isMediaDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            Uri contentUri = null;
            if ("image".equals(type)) {
                contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
            } else if ("video".equals(type)) {
                contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
            } else if ("audio".equals(type)) {
                contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
            }

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

            return getDataColumn(context, contentUri, selection, selectionArgs);
        }
    }
    // MediaStore (and general)
    else if ("content".equalsIgnoreCase(uri.getScheme())) {

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

        return getDataColumn(context, uri, null, null);
    }
    // File
    else if ("file".equalsIgnoreCase(uri.getScheme())) {
        return uri.getPath();
    }

    return null;
}

從設備中選擇視頻后，我在我的MainActivity調用它，在onActivityResult ：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == SELECT_VIDEO_REQUEST && resultCode == RESULT_OK) {

        if (Build.VERSION.SDK_INT >= 19) {
            
            //Calling FileUtils class
            String sourcePath = FileUtils.getPath(getApplicationContext(), data.getData());
          
            Intent intent = new Intent();
            intent.setClass(MainActivity.this, PlayerActivity.class);
            intent.putExtra("videoUri", sourcePath);
            startActivity(intent);

        } else {
            //Not relevant to the question
            .......

        }
    }
    if (requestCode == SELECT_VIDEO_REQUEST && resultCode != RESULT_OK) {
        Toast.makeText(getApplicationContext(), "Failed to select video", Toast.LENGTH_LONG).show();
    } else {
        super.onActivityResult(requestCode, resultCode, data);
    }


}

在我的PlayerActivity我得到String並嘗試解析Uri ，如下所示：

//Getting String from Intent
mStringFilePath = getIntent().getStringExtra("videoUri");
//Parse Uri from String
mVideoUri = Uri.parse(mStringFilePath);

在我的設備上測試時，我沒有問題。 我得到了正確的路徑並且Uri.parse工作正常。 但是我在我的 Crashlytics 上看到很多崩潰說 - nullpointerexception at line 59 ，指的是mVideoUri = Uri.parse(mStringFilePath);

我究竟做錯了什么？ 為什么它在我的設備上工作並在其他一些設備上返回 null？

編輯 1

我忘了在我的清單中添加<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /> 。 我至少沒有得到nullpointerexception ，但我得到以下信息 -

java.io.FileNotFoundException: Not found (No such file or directory)

當我從 SD 卡中選擇文件時，不知何故Uri不正確，有什么原因嗎？

Answer 1

崩潰可能是由於mStringFilePath = getIntent().getStringExtra("videoUri");上的空字符串而發生的mStringFilePath = getIntent().getStringExtra("videoUri"); 由於getIntent().getStringExtras()不會拋出 nullpointerexception 如果請求的 Extras 沒有值，但也不會向分配的變量提供數據，因此mStringFilePath的最終結果將為 null 以解決此問題確保 uri 解析的給定字符串包含在：

if(mStringFilePath != null){ mVideoUri = Uri.parse(mStringFilePath); }