Can't get camera code from Android docs to wor

问题:

I am using code from http://developer.android.com/training/camera/photobasics.html

Code:

    private void dispatchTakePictureIntent() {
        Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        if (takePictureIntent.resolveActivity(getActivity().getPackageManager()) != null) {
            File photoFile = null;
            try {
                photoFile = FileUtilities.createImageFile();
            } catch (IOException ex) {
                // Error occurred while creating the File
                Toast.makeText(getActivity(),"Error!",Toast.LENGTH_SHORT).show();
            }
            if (photoFile != null) {
                takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT,
                        Uri.fromFile(photoFile));
                startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
            }
        }
    }


    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == Activity.RESULT_OK) {
            Bundle extras = data.getExtras(); //error
            //code after this doesn't get executed
        }
    }

I'm trying to get access to the thumbnail and the picture being stored on the device. But for some reason when I try the code, I get a null pointer exception on the data.getExtras(); part.

What am I missing here?

回答1:

That's one of notorious Android development experience.

Android Intent does not guarantee to give captured image in data.getExtras(), especially user utilize 3rd party camera/imaging app. You can find many trials and suggestions in here and anywhere googled with "android camera intent null".

Some common of them are as below.

1. data.getExtras().get("data");
2. data.getExtras() with different key (i.e "photo")
3. data.getData()
4. Uri.fromFile(f) for EXTRA_OUTPUT predefined path.
5. Uri.fromFile(f) with some random filename (datetime format or IMG-xxx) without maintaining EXTRA_OUTPUT definition.

I recommend you to find it using breakpoint which route of the variable that the intent given. It would be good to check all of them in if-else if-else approach.

In addition, check out crash report carefully after releasing the app. You may get the error out of the above trials.

回答2:

To get the ThumbNail, you don't need to create a file etc. please try this code below.

   Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            // Ensure that there's a camera activity to handle the intent
            if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
                    startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
                }

and to get the results.

 @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

            if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
                Bundle extras = data.getExtras();
                Bitmap imageBitmap = (Bitmap) extras.get("data");
                imgView.setImageBitmap(imageBitmap);
            }

    }

imgView is the ImageView you want to set the ThumbNail to.

In case if you want to create a file and then try this, [ which is not needed for a Thumbnail], you may want to try adding the following permission to manifest as you are trying to read and write to storage.

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

All the best.