当前我想使用使用Android camera api1创建一个demo.一个画布，底部一个按钮作为拍照键。展示图片并保存到系统相册。右下角在添加一个相册图标用于显示最后一张缩略图。

好的，以下是实现步骤：

1. 在 AndroidManifest.xml 文件中添加相机和存储权限：

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2. 在布局文件中添加一个 SurfaceView 作为相机预览，一个 Button 作为拍照按钮，一个 ImageView 作为展示图片的容器，一个 ImageButton 作为最后一张缩略图的容器：

<SurfaceView
    android:id="@+id/surfaceView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<Button
    android:id="@+id/takePhotoButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Take photo"
    android:layout_gravity="bottom|center_horizontal" />

<ImageView
    android:id="@+id/photoImageView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:visibility="gone" />

<ImageButton
    android:id="@+id/thumbnailImageButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentRight="true"
    android:src="@drawable/ic_photo_library_black_24dp" />

3. 在 Activity 中获取视图控件，并实现拍照逻辑：

public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {

    private Camera camera;
    private SurfaceView surfaceView;
    private SurfaceHolder surfaceHolder;
    private Button takePhotoButton;
    private ImageView photoImageView;
    private ImageButton thumbnailImageButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        surfaceView = findViewById(R.id.surfaceView);
        takePhotoButton = findViewById(R.id.takePhotoButton);
        photoImageView = findViewById(R.id.photoImageView);
        thumbnailImageButton = findViewById(R.id.thumbnailImageButton);

        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);

        takePhotoButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                camera.takePicture(null, null, pictureCallback);
            }
        });

        thumbnailImageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO: 显示最后一张缩略图
            }
        });
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            camera = Camera.open();
            camera.setPreviewDisplay(surfaceHolder);
            camera.startPreview();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // 重新设置相机预览的大小和方向
        Camera.Parameters parameters = camera.getParameters();
        Camera.Size previewSize = getBestPreviewSize(parameters, width, height);
        parameters.setPreviewSize(previewSize.width, previewSize.height);
        camera.setParameters(parameters);
        camera.setDisplayOrientation(90);
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        camera.stopPreview();
        camera.release();
    }

    private Camera.PictureCallback pictureCallback = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            // 将图片保存到系统相册
            File pictureFile = getOutputMediaFile();
            if (pictureFile == null) {
                Log.d("MainActivity", "Error creating media file, check storage permissions");
                return;
            }
            try {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            } catch (FileNotFoundException e) {
                Log.d("MainActivity", "File not found: " + e.getMessage());
            } catch (IOException e) {
                Log.d("MainActivity", "Error accessing file: " + e.getMessage());
            }

            // 显示图片并隐藏相机预览
            photoImageView.setImageBitmap(BitmapFactory.decodeByteArray(data, 0, data.length));
            surfaceView.setVisibility(View.GONE);
            photoImageView.setVisibility(View.VISIBLE);
        }
    };

    private static File getOutputMediaFile() {
        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES), "MyCameraApp");
        if (!mediaStorageDir.exists()) {
            if (!mediaStorageDir.mkdirs()) {
                return null;
            }
        }
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                "IMG_" + timeStamp + ".jpg");
        return mediaFile;
    }

    private static Camera.Size getBestPreviewSize(Camera.Parameters parameters, int width, int height) {
        Camera.Size bestSize = null;
        List<Camera.Size> sizeList = parameters.getSupportedPreviewSizes();
        bestSize = sizeList.get(0);
        for (int i = 1; i < sizeList.size(); i++) {
            if ((sizeList.get(i).width * sizeList.get(i).height) >
                    (bestSize.width * bestSize.height)) {
                bestSize = sizeList.get(i);
            }
        }
        return bestSize;
    }
}

4. 实现显示最后一张缩略图的逻辑，可参考以下代码：

private void showLastThumbnail() {
    String[] projection = {MediaStore.Images.Media.DATA};
    Cursor cursor = getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
            projection, null, null, MediaStore.Images.Media.DATE_ADDED + " DESC LIMIT 1");
    if (cursor != null && cursor.moveToFirst()) {
        String imagePath = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
        Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
        thumbnailImageButton.setImageBitmap(bitmap);
        cursor.close();
    }
}

以上就是使用 Android camera api1 创建一个 demo 的全部步骤，希望可以帮到你。