将content://URI转换为Android 4.4中的实际路径

Question

我尝试了一个可以正常工作的解决方案（见下文），除了在Android 4.4中调用starActivityForResult（）会带来一个名为“从”打开的活动，其中有“最近”、“图像”、“下载”以及几个应用程序可供选择。当我选择图像并尝试解析返回的内容URI（使用下面的代码）时，调用cursor.getString（）返回null。如果我使用库应用程序选择完全相同的文件，cursor.getString（）返回文件路径。我只在API级别16和19中测试过这个。一切工作在16预期。至于19去，我必须选择画廊或其他应用程序，否则它不起作用。

private String getRealPathFromURI(Context context, Uri contentUri) {
    Cursor cursor = null;
    try { 
        String[] proj = { MediaStore.Images.Media.DATA };
        cursor = context.getContentResolver().query(contentUri,  proj, null, null, null);
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        String path = cursor.getString(column_index);

        return path;
    } finally {
        if (cursor != null) {
            cursor.close();
        }
    }
}

Answer 1

我也一直面临这个问题，但在我的例子中，我想做的是为库指定一个具体的Uri，以便以后使用crop。看起来在KitKat的新文档浏览器中，我们不能再这样做了，除非您在导航抽屉中选择galery，并且，如您所说，直接从那里打开图像或文件。

在Uri的情况下，您仍然可以在从文档浏览器打开时检索路径。

    Intent dataIntent= new Intent(Intent.ACTION_GET_CONTENT);
    dataIntent.setType("image/*"); //Or whatever type you need

然后在onActivityResult中：

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == ACTIVITY_SELECT_IMAGE && resultCode == RESULT_OK) {
        myUri = data.getData();
        String path = myUri.getPath();
        openPath(myUri);

    }
}

如果需要使用该路径打开文件，只需使用内容解析器即可：

public void openPath(Uri uri){
    InputStream is = null;
    try {
        is = getContentResolver().openInputStream(uri);
        //Convert your stream to data here
        is.close();

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

Answer 2

将content://URI转换为Android 4.4中的实际路径

在任何Android版本上都没有可靠的方法可以做到这一点。content://Uri不必表示文件系统上的文件，更不用说您能够访问的文件了。

Android 4.4提供存储框架的更改只是增加了您遇到内容：//Uri值的频率。

如果您获得一个内容：//Uri，请使用内容解析程序和openInputStream（）和openOutputStream（）等方法使用它。

Answer 3

这将从MediaProvider、DownloadsProvider和ExtranalStorageProvider获取文件路径，同时返回到您提到的非官方ContentProvider方法。

   /**
 * 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 getPath(final Context context, final Uri uri) {

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

    // DocumentProvider
    if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
        // ExternalStorageProvider
        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];
            }

            // TODO handle non-primary volumes
        }
        // 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 getDataColumn(context, uri, null, null);
    }
    // File
    else if ("file".equalsIgnoreCase(uri.getScheme())) {
        return uri.getPath();
    }

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

/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is DownloadsProvider.
 */
public static boolean isDownloadsDocument(Uri uri) {
    return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}

/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is MediaProvider.
 */
public static boolean isMediaDocument(Uri uri) {
    return "com.android.providers.media.documents".equals(uri.getAuthority());
}

源aFileChooser