I am new to Android development. I created my first app which is a camera with the ability to capture an image, query the user for a Car ID related to the image, preview the captured image, and upload that image to the server.
I am interested in randomly sending out one image from possibly multiple such as from the image directory to the server. I do NOT want to send multiple images to the server--just one random image.
Upon much research on this website as well as on numerous others, I determined the following: I must obtain the image directory to where the captured images are uploaded to, I must randomly select an image from said directory using the random capability in Android, I must set up the image bitmap based on the file uri of the image, and I must convert the bitmap to a blob data type by base64 encoding.
I did the above, but my bitmap returned as null since I receive the message, "Please select image", which was the toast message for that instance.
Here is my code:
public class MainActivity extends Activity {
// Activity request codes.
private static final int CAMERA_CAPTURE_IMAGE_REQUEST_CODE = 100;
public static final int MEDIA_TYPE_IMAGE = 1;
Bitmap bitmap;
ProgressDialog pd;
InputStream is;
//Directory name to store captured images.
private static final String IMAGE_DIRECTORY_NAME = "Hello Camera";
private Uri fileUri; //File url to store captured images.
private ImageView imgPreview;
private Button btnCapturePicture;
private Button upload;
Button mButton;
EditText mEdit;
/* Initializes activity, defines UI layout, and retrieves widgets
* to interact with.
* @param savedInstanceState - data is caught here and saved for
* future app use.
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mButton = (Button)findViewById(R.id.button);
mEdit = (EditText)findViewById(R.id.edittext);
mButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Log.v("EditText", mEdit.getText().toString());
}
});
imgPreview = (ImageView) findViewById(R.id.imgPreview);
btnCapturePicture = (Button) findViewById(R.id.btnCapturePicture);
upload = (Button) findViewById(R.id.upload);
upload.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (bitmap == null) {
Toast.makeText(getApplicationContext(), "Please Select Image", Toast.LENGTH_LONG).show();
} else {
new ImageUpload().execute();
}
}
});
/**
* Captures image button click event in order to capture a photo.
* @param new View.OnClickListener- call to constructor
*/
btnCapturePicture.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//Captures an image.
captureImage();
}
});
//Checks for camera availability.
if (!isDeviceSupportCamera()) {
Toast.makeText(getApplicationContext(),
"Sorry! Your device doesn't support camera", Toast.LENGTH_LONG).show();
//Closes if a camera is not available on the device.
finish();
}
}
/**
* Checks if device has camera hardware.
*
* @return - true or false.
*/
private boolean isDeviceSupportCamera() {
if (getApplicationContext().getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
//Device has a camera.
return true;
} else {
// Device does not have a camera.
return false;
}
}
/*
* Launches camera app request image capture.
*/
private void captureImage() {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri);
//Starts the image capture Intent.
startActivityForResult(intent, CAMERA_CAPTURE_IMAGE_REQUEST_CODE);
}
/**
* Gets and stores the file url. Will be null after returning from camera
* app.
*
* @param outState - Holds per-instance state from activity.
*/
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// Saves the file url in bundle. It will be null on screen orientation changes.
outState.putParcelable("file_uri", fileUri);
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
//Gets the file url.
fileUri = savedInstanceState.getParcelable("file_uri");
}
/**
* Receives activity result method. Will be called after closing the camera.
*
* @param requestCode - Requests to capture an image.
* @param resultCode - Based on success or failure of image capturing, shows
* an image preview or one of two error messages.
* @param data - Carries the result data(successfully captured image).
* @return - An image preview, or one of two error messages.
*/
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
//If the result is the image capturing event,
if (requestCode == CAMERA_CAPTURE_IMAGE_REQUEST_CODE) {
if (resultCode == RESULT_OK) {
//the image was successfully captured
// and will be displayed in the preview.
previewCapturedImage();
} else if (resultCode == RESULT_CANCELED) {
//The user cancelled the image capturing.
Toast.makeText(getApplicationContext(),
"User cancelled image capture", Toast.LENGTH_SHORT).show();
} else {
//Image capturing failed, but the user did not actually cancel it.
Toast.makeText(getApplicationContext(),
"Sorry! Failed to capture image", Toast.LENGTH_SHORT).show();
}
}
}
/**
* Displays the image from a path to ImageView.
* Downsizes an image if necessary and throws exception
* if the image is too large.
*/
private void previewCapturedImage() {
try {
imgPreview.setVisibility(View.VISIBLE);
upload.setVisibility(View.VISIBLE);
File mediaStorageDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
File[] listFiles = mediaStorageDir.listFiles();
Random r = new Random ();
File randomPicture = listFiles[r.nextInt(listFiles.length)];
Uri pictureUri = Uri.fromFile(randomPicture);
BitmapFactory.Options options = new BitmapFactory.Options();
// Downsizes images. Will throw OutOfMemory Exception for larger images.
options.inSampleSize = 8;
bitmap = BitmapFactory.decodeFile(pictureUri.getPath(), options);
ImageView imgView = (ImageView) findViewById(R.id.imgPreview);
imgView.setImageBitmap(bitmap);
} catch (NullPointerException e) {
e.printStackTrace();
}
}
/**
* Creates the file uri to store an image.
*
* @param type - Refers to the captured image.
* @return Uri.fromFile - The file uri to store an image.
*/
public Uri getOutputMediaFileUri(int type) {
return Uri.fromFile(getOutputMediaFile(type));
}
/**
* Returns the captured image.
*
* @param type - Refers to the captured image.
* @return null or mediaFile - mediaFile: Captured
* image inside of timestamped file.
*/
private static File getOutputMediaFile(int type) {
// External sdcard location.
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
IMAGE_DIRECTORY_NAME);
// Create the storage directory if it does not exists
if (!mediaStorageDir.exists()) {
if (!mediaStorageDir.mkdirs()) {
Log.d(IMAGE_DIRECTORY_NAME, "Oops! Failed create " + IMAGE_DIRECTORY_NAME + " directory");
return null;
}
}
// Creates a media file name corresponding to a timestamp.
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator + "IMG_" + timeStamp + ".jpg");
} else {
return null;
}
return mediaFile;
}
/*
* Uploads the saved and captured image to the server.
*/
public class ImageUpload extends AsyncTask<String, String,String> {
String postUrl = "";
public void postURL(String url) {
postUrl = url;
}
/**
* Compresses the selected gallery image and encodes
* compressed image to a base64 string.
*
* @param params
*/
@Override
protected String doInBackground(String... params) {
String result = null;
try {
HttpClient client = new DefaultHttpClient();
String postURL = "";
HttpPost post = new HttpPost("http://ift.tt/1J0913I");
ArrayList<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();
String msg = mEdit.getText().toString();
nameValuePair.add(new BasicNameValuePair("carid",msg));
//Converts image file uri to blob base64
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 90, stream);
byte[] byte_arr = stream.toByteArray();
String image_str = new String(Base64.encode(byte_arr, Base64.DEFAULT));
nameValuePair.add(new BasicNameValuePair("carimage", image_str));
UrlEncodedFormEntity ent = new UrlEncodedFormEntity(nameValuePair, HTTP.UTF_8);
post.setEntity(ent);
HttpResponse responsePOST = client.execute(post);
HttpEntity resEntity = responsePOST.getEntity();
result = EntityUtils.toString(resEntity);
if (resEntity != null) {
Log.i("RESPONSE", EntityUtils.toString(resEntity));
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
@Override
protected void onPostExecute(String result) {
if (result != null) {
Toast.makeText(getApplicationContext(),
"Successfully uploaded", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getApplicationContext(),
"Sorry! Failed to upload", Toast.LENGTH_SHORT).show();
}
}
}
}
I am confused as to why the bitmap is returning null. I appreciate any insight as to why as well as any suggestions of how to improve my current code for my interested goal. Thank you greatly.
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