Question

我正在按照Google的官方文档编写相机和图库应用。问题在于，它主要侧重于如何拍照以及如何将其保存在内存中。我通过getExternalFilesDir（）将它们保存在应用程序的外部存储器中。

我现在想要做的是通过MediaStore来简单地查询保存了照片的目录，以便在回收者视图中显示其中的所有照片。但是我似乎找不到任何有关如何进行检索的解释。 Uri出了点问题，我可能不太了解，也不知道如何解决。即使在https://developer.android.com/training/data-storage/files#PrivateFiles中，该文章也只讨论将文件保存在各种存储选项中，而不是检索它们。

这是我保存文件的代码：

private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";

    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
            imageFileName,  /* prefix */
            ".jpg",   /* suffix */
            storageDir     /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    currentPhotoPath = image.getAbsolutePath();
    return image;
}

这是实际发送意图的函数（然后onActivityResult处理返回的数据）：

private void dispatchTakePictureIntent() {
    final String TAG = "dispatchTakePic: ";
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {

        // Create the File where the photo should go
        File photoFile = null;
        try {
            photoFile = createImageFile();
        } catch (IOException ex) {
            // Error occurred while creating the File
            Log.e(TAG, "Error while creating a file");
            ex.printStackTrace();
        }

        // Continue only if the File was successfully created
        // Authority has to be exactly like in manifest
        if (photoFile != null) {
            Uri photoURI = FileProvider.getUriForFile(
                    this,
                    "com.example.android.fileprovider",
                    photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
        }
    }
}

这是我尝试获取有关所拍摄照片的信息的代码：

private void populatePhotoArray() {
    final String TAG = "popPhotoArray: ";
    ContentResolver contentResolver = getContentResolver();
    String photo_id, photo_title, photo_path = "";

    final String[] PHOTOGRAPHS_PROJECTION = {
            MediaStore.Images.Media._ID,
            MediaStore.Images.Media.TITLE,
            MediaStore.Images.Media.DATA};

    File photographsDirectory = getExternalFilesDir(Environment.DIRECTORY_MOVIES);
    Uri photographsUri = Uri.fromFile(photographsDirectory);
    //Uri photographsUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
    //Uri photographsUri = MediaStore.Images.Media.INTERNAL_CONTENT_URI;
    String sortOrder = MediaStore.Images.Media.DATE_ADDED + " DESC";
    final Cursor cursor = contentResolver.query(
            photographsUri,
            PHOTOGRAPHS_PROJECTION,
            null,
            null,
            sortOrder);

    Log.d(TAG, "created the projection");

    if (cursor != null && cursor.getCount() > 0) {
        while (cursor.moveToNext()) {
            photo_id = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media._ID));
            photo_title = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.TITLE));
            photo_path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));

            // save to photo list
            applicationPhotosList.add(new Photographs(photo_id, photo_title, photo_path));
            Log.d(TAG, "new photo added");
        }
        cursor.close();
        Log.d(TAG, "Photo array filled up");
    }
    else if (cursor == null){
        Log.d(TAG, "No photos present, cursor is null");
        Toast.makeText(this, "No photos present", Toast.LENGTH_SHORT).show();
    }

似乎试图将getExternalFileDir（）的路径转换为Uri无效。光标为空。但是MediaStore仅具有MediaStore.Images.Media.EXTERNAL_CONTENT_URI，这不适合查询整个设备的内存，而我只需要该应用程序在其中保存所拍摄图片的特定目录。我想念什么？不会那么难，对吧？

Answer 1

还有另一种方法可以不使用光标从特定文件夹中检索图像，我认为它更快。

    private fun getAllShownImagesPath(): ArrayList<String> {

    var filePath: ArrayList<String> = ArrayList<String>()
    val path = File(getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).path, "BacFo Camera")
    if (path.exists()) {

        for (i in path.list().iterator()) {

            filePath?.add("" + path.toString() + "/" + i)
        }
    }

    return filePath!!
    }

` 在“文件名”中，您将拥有所有图像或视频的路径，无论保存在特定文件夹中的是什么

如何通过MediaStore从getExternalFilesDir路径查询所有图像

1 个答案: