从Android应用内摄像头拍照并上传到服务器的更高效的方法

Question

我正在建立一个应用程序，需要从应用程序内相机拍照的方法，但对于一些安卓设备(旧设备或低内存)，它是相当冻结时，拍照触发。有没有什么代码可以修改或优化，让用户体验更好？

//this function trigger to take picture (or screenshot) from user screen
    private void captureImage() {
        mPreview.setDrawingCacheEnabled(true);
        final Bitmap[] drawingCache = {Bitmap.createBitmap(mPreview.getDrawingCache())};
        mPreview.setDrawingCacheEnabled(false);

     mCameraSource.takePicture(null, bytes -> {
            int orientation = Exif.getOrientation(bytes);
            Bitmap temp = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
            Bitmap picture = rotateImage(temp, orientation);
            assert picture != null;
            Bitmap overlay = Bitmap.createBitmap(mGraphicOverlay.getWidth(), mGraphicOverlay.getHeight(), picture.getConfig());
            Canvas canvas = new Canvas(overlay);

            Matrix matrix = new Matrix();
            matrix.setScale((float) overlay.getWidth() / (float) picture.getWidth(), (float) overlay.getHeight() / (float) picture.getHeight());

            // mirror by inverting scale and translating
            matrix.preScale(-1, 1);
            matrix.postTranslate(canvas.getWidth(), 0);

            Paint paint = new Paint();
            canvas.drawBitmap(picture, matrix, paint);
            canvas.drawBitmap(drawingCache[0], 0, 0, paint);

//this function to save picture taken and put it on app storage cache
            try {
                String mainpath = getApplicationContext().getFilesDir().getPath() + separator + "e-Presensi" + separator;
                File basePath = new File(mainpath);
                if (!basePath.exists())
                    Log.d("CAPTURE_BASE_PATH", basePath.mkdirs() ? "Success" : "Failed");

//this function to get directory path of saved photo
                String path = mainpath + "photo_" + getPhotoTime() + ".jpg";
                String namafotoo = "photo_" + getPhotoTime() + ".jpg";
                filePath = path;

                namafoto = namafotoo;
                SessionManager.createNamaFoto(namafoto);

                File captureFile = new File(path);
                boolean sucess = captureFile.createNewFile();
                if (!captureFile.exists())
                    Log.d("CAPTURE_FILE_PATH", sucess ? "Success" : "Failed");
                FileOutputStream stream = new FileOutputStream(captureFile);
                overlay.compress(Bitmap.CompressFormat.WEBP, 60, stream);
                stream.flush();
                stream.close();
                if (!picture.isRecycled()) {
                    picture.recycle();
                }

                if (drawingCache[0] != null && !drawingCache[0].isRecycled()) {
                    drawingCache[0].recycle();
                    drawingCache[0] = null;
                }
                mPreview.setDrawingCacheEnabled(false);
                uploadPicture();
                finish();

            } catch (IOException e) {
                e.printStackTrace();
            }
        });
    }

谢谢你的帮助。

Answer 1

通常，我建议您单步执行代码并查看在每一行上生成的大量内存资源，如果完成，请考虑在遍历整个方法时积极地将这些资源设置为null。

例如，您有一个名为temp的变量，它的大小为"Y“个字节，您似乎要旋转它，然后再也不使用temp。如果picture是temp的旋转副本，那么您现在已经使用了2Y字节的内存来保存temp和picture。我怀疑，如果你在创建picture后简单地将temp设置为null，你可能会释放一半的内存，而这些内存是你的旧/慢手机非常需要的。

采用相同的概念，并遵循您的方法的其余部分，看看是否可以找到其他优化。基本上，在创建不会使用的图像数据副本的任何地方，都应该立即将其设置为null，以便垃圾收集器可以积极地将其丢弃。

Answer 2

首先，你需要一些变量：

byte[] byteArray_IMG;
String currentPhotoPath;
static final int REQUEST_TAKE_PHOTO = 1;
ImageView imageView; // maybe you need show the photo before send it

然后定义拍摄照片的方法：

  private void dispatchTakePictureIntent() {
    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) {
            Toast.makeText(getApplicationContext(),Error takin the photo",Toast.LENGTH_LONG).show();
        }

        // Continue only if the File was successfully created
        if (photoFile != null) {
            path_img = photoFile.toString();
            Uri photoURI = FileProvider.getUriForFile(this,"com.app.yournmamepackage.fileprovider" , photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
        }
    }
}

创建创建文件镜像的方法

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;
}

覆盖活动结果以：

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

    if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {

 /*            Bundle extras =  data.getExtras();
        Bitmap imageBitmap = (Bitmap)  extras.get("data");

        imageView.setImageBitmap(imageBitmap);

        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        imageBitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);

        byteArray_IMG = stream.toByteArray();*/

        MediaScannerConnection.scanFile(this, new String[]{path_img}, null,
                new MediaScannerConnection.OnScanCompletedListener() {
                    @Override
                    public void onScanCompleted(String path, Uri uri) {
                        Log.i("path",""+path);
                    }
                });

        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        Bitmap imageBitmap = BitmapFactory.decodeFile(path_img);
        imageBitmap.compress(Bitmap.CompressFormat.JPEG, 14, stream);
        imageView.setImageBitmap(imageBitmap);
        byteArray_IMG = stream.toByteArray();
    }
}

记住这一点非常重要

imageBitmap.compress(Bitmap.CompressFormat.JPEG, 25, stream)

 // 25 is photo quality  0-100

然后，您可以在异步过程中上传图片

Answer 3

首先，在您的活动/片段中的onCreate()方法上初始化这些变量

val FILE_NAME:String="photo.jpg"     //give any name with.jpg extension
private var imageuri: Uri?=null
val REQUEST_IMAGE=111

现在打开摄像头

val intent: Intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)

        photofile = getphotofile(FILE_NAME)
        imageuri = activity?.let { it1 -> FileProvider.getUriForFile(it1, "//your package name here//.fileprovider", photofile) }     //put your package name
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageuri)
        startActivityForResult(int, REQUEST_IMAGE)

onActivityResult()方法

if(requestCode==REQUEST_IMAGE && resultCode == Activity.RESULT_OK){
        val progressdialog: ProgressDialog = ProgressDialog(activity)
        progressdialog.setTitle("Sending Image....")         
        progressdialog.show()                   //start your progressdialog

        val ref= FirebaseDatabase.getInstance().reference
        val messagekey=ref.push().key          //create a key to store image in firebase

        var bmp: Bitmap?=null
        try {
            bmp=MediaStore.Images.Media.getBitmap(activity?.contentResolver,imageuri)   //get image in bitmap
        } catch (e: IOException) {
            e.printStackTrace();
        }
        val baos= ByteArrayOutputStream()
        bmp!!.compress(Bitmap.CompressFormat.JPEG,50,baos)   //compress the quality of image to 50 from 100
        val fileinBytes: ByteArray =baos.toByteArray()

        val store: StorageReference = FirebaseStorage.getInstance().reference.child("Chat Images/")    //create a child reference in firebase
        val path=store.child("$messagekey.jpg")    //store a message in above reference with the unique key created above with .jpg extension
        val uploadTask: StorageTask<*>
        uploadTask=path.putBytes(fileinBytes)    //it will upload the image to firebase at given path

        uploadTask.continueWithTask(Continuation<UploadTask.TaskSnapshot, Task<Uri>> { task ->
            if (!task.isSuccessful) {
                task.exception?.let {
                    throw it
                }
                Toast.makeText(activity, "Upload Failed", Toast.LENGTH_SHORT).show()
            }
            return@Continuation path.downloadUrl
        }).addOnCompleteListener { task->
            if(task.isSuccessful){

                url=task.result.toString()   //get the url of uploaded image
                
                //Do what you want with the url of your image                     

                progressdialog.dismiss()
                Toast.makeText(activity, "Image Uploaded", Toast.LENGTH_SHORT).show()
            }
        }.addOnFailureListener { e->
            progressdialog.dismiss()
            Toast.makeText(activity, "Failed " + e.message, Toast.LENGTH_SHORT)
                    .show();
        }
        uploadTask.addOnProgressListener { task->
            var progress:Double=(100.0*task.bytesTransferred)/task.totalByteCount
            progressdialog.setMessage("Sending ${progress.toInt()}%")   //this will show the progress in progress bar 0-100%
        }

    }