android - 如何知道图像是来自相机还是文件系统

Question

此代码用于以前版本的 Android，因为来自 onActivityResult 中的 Intent 的数据如果图像来自相机，将返回 null，如果图像是从文件系统中选择的，它将保存一个 Uri。然而，在 Lollipop 上，相机 Intent 也返回一个 Uri。我如何知道图像是用相机拍摄的还是从文件存储/图库中选择的？

这是我的代码:

private void openImageIntent() {

        // Determine Uri of camera image to save.
        final File root = new File(Environment.getExternalStorageDirectory()
                + File.separator + "Klea" + File.separator);
        root.mkdirs();
        final String fname = getUniqueImageFilename();
        final File sdImageMainDirectory = new File(root, fname);
        outputFileUri = Uri.fromFile(sdImageMainDirectory);

        // Camera.
        final List<Intent> cameraIntents = new ArrayList<Intent>();
        final Intent captureIntent = new Intent(
                android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
        final PackageManager packageManager = getActivity().getPackageManager();
        final List<ResolveInfo> listCam = packageManager.queryIntentActivities(
                captureIntent, 0);
        for (ResolveInfo res : listCam) {
            final String packageName = res.activityInfo.packageName;
            final Intent intent = new Intent(captureIntent);
            intent.setComponent(new ComponentName(res.activityInfo.packageName,
                    res.activityInfo.name));
            intent.setPackage(packageName);
            intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);
            cameraIntents.add(intent);
        }

        // Filesystem.
        final Intent galleryIntent = new Intent();
        galleryIntent.setType("image/*");
        galleryIntent.setAction(Intent.ACTION_GET_CONTENT);

        // Chooser of filesystem options.
        final Intent chooserIntent = Intent.createChooser(galleryIntent,
                getString(R.string.chose_source));

        // Add the camera options.
        chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS,
                cameraIntents.toArray(new Parcelable[] {}));

        startActivityForResult(chooserIntent, REQUEST_IMAGE_CAPTURE);
    }

    private static String getUniqueImageFilename() {
        // TODO Auto-generated method stub
        String fileName = "img_" + System.currentTimeMillis() + ".jpg";
        return fileName;
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        Log.d("reqCode", Integer.toString(requestCode));
        Log.d("resCode", Integer.toString(resultCode));
        Log.d("data", data.toString());
        getActivity();
        if (resultCode == Activity.RESULT_OK) {
            if (requestCode == REQUEST_IMAGE_CAPTURE) {
                final boolean isCamera;
                if (data == null) {
                    isCamera = true;
                } else {
                    final String action = data.getAction();
                    if (action == null) {
                        isCamera = false;
                    } else {
                        isCamera = action
                                .equals(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
                    }
                }

                Uri selectedImageUri;
                if (isCamera) {
                    File file = new File(outputFileUri.toString());
                    Log.d("old file", file.toString());
                    String temp = file.toString().replace("file:", "");
                    Log.d("new file", temp);
                    selectedImageUri = Uri.parse(temp);
                } else {
                    Uri selectedImage = data.getData();
                    String[] filePathColumn = {MediaStore.Images.Media.DATA};

                    Cursor cursor = getActivity().getContentResolver().query(
                            selectedImage, filePathColumn, null, null, null);
                    cursor.moveToFirst();
                    int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
                    selectedImageUri = Uri.parse(cursor.getString(columnIndex));
                    cursor.close();
                }
            }
        }
    }

Answer 1

首先，无法为您提供任何保证。用户可以选择在其 list 中声明 MediaStore.ACTION_IMAGE_CAPTURE Intent 的任何应用，并且该应用可以决定从文件系统中选择图片。

其次，看看新的createChooser()采用 IntentSender 的方法参数返回最终用户的选择供您分析，参见this example (不幸的是，这是 22 岁及以上)。

第三，您提供 outputFileUri 作为 MediaStore.EXTRA_OUTPUT - 该文件有望由相机创建，但会被文件系统选择器忽略；现在，如果您只在调用启动 Intent 之前 进行清理，就可以轻松检查文件是否包含新图片。

我同意你的conclusion基于data.dat (content://media/... -> file, file:/... -> camera) 的选择不是足够可靠。

所以最重要的是，可以像这样进行简单但可靠的区分:

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode == Activity.RESULT_OK) {
        if (requestCode == REQUEST_IMAGE_CAPTURE) {
            final boolean isCamera = new File(outputFileUri.getPath()).length() > 0;
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