如何在上传到 Firebase 之前压缩图像？

Question

我正在创建一个社交网络应用程序，用户可以在其中发布图像，因此当用户上传其图像时，它的尺寸非常大，而当我检索该图像时，使用 Picasso 会花费太多时间。 有没有办法在上传之前压缩这些图像而不会造成明显的质量损失，以便可以非常有效和快速地检索它们。 P.S：我使用 Firebase 作为后端服务器。

这是我上传图片的代码。

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

    if(requestCode == Gallery_Pick && resultCode == RESULT_OK && data != null){
        ImageUri = data.getData();
        SelectPostImage.setImageURI(ImageUri);
    }
    super.onActivityResult(requestCode, resultCode, data);
}

final StorageReference filePath = PostImagesRef.child("Post Images").child(ImageUri.getLastPathSegment() + postRandomName + ".jpg");

    final UploadTask uploadTask = filePath.putFile(ImageUri);

    uploadTask.addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception e) {
            String message = e.toString();
            Toast.makeText(PostActivity.this, "Some Error Occured"+message, Toast.LENGTH_SHORT).show();
            loadingBar.dismiss();
        }
    }).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
            Toast.makeText(PostActivity.this, "Image Uploaded Successfully", Toast.LENGTH_SHORT).show();
            Task<Uri> urlTask = uploadTask.continueWithTask(new Continuation<UploadTask.TaskSnapshot, Task<Uri>>() {
                @Override
                public Task<Uri> then(@NonNull Task<UploadTask.TaskSnapshot> task) throws Exception {
                    if(!task.isSuccessful()){
                        throw task.getException();
                    }
                    downloadImageUrl = filePath.getDownloadUrl().toString();

                    return filePath.getDownloadUrl();
                }
            }).addOnCompleteListener(new OnCompleteListener<Uri>() {
                @Override
                public void onComplete(@NonNull Task<Uri> task) {
                    if(task.isSuccessful()){

                        downloadImageUrl = task.getResult().toString();
                        Toast.makeText(PostActivity.this, "Saved To Database Successfully", Toast.LENGTH_SHORT).show();
                        SavingPostInformationToDatabase();

                    }
                }
            });
        }
    });

请帮助我。任何帮助或建议都将是可观的。 提前致谢。！！ :)

Answer 1

您可以简单地使用 Glide 调整图片大小并使用该图片上传到 firebase

Glide.with(requireActivity())
                .asBitmap()
                .override(YOUR_IMAGE_SIZE, YOUR_IMAGE_SIZE)
                .load(uri)
                .into(object : CustomTarget<Bitmap>() {
                    override fun onResourceReady(
                        resource: Bitmap,
                        transition: Transition<in Bitmap>?
                    ) {

                        // using bitmapToByte(resource) -> byte
                        // using filePath.putBytes(data) -> uploadTask
                         val filePath = PostImagesRef.child("Post Images").child(ImageUri.getLastPathSegment() + postRandomName + ".jpg")

                         val uploadTask = filePath.putBytes(bitmapToByte(resource))
                    }

                    override fun onLoadCleared(placeholder: Drawable?) {
                        // this is called when imageView is cleared on lifecycle call or for
                        // some other reason.
                        // if you are referencing the bitmap somewhere else too other than this imageView
                        // clear it here as you can no longer have the bitmap
                    }
                })

bitmapToByte函数

 fun bitmapToByte(bitmap: Bitmap): ByteArray {
    val stream = ByteArrayOutputStream()
    bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream)
    return stream.toByteArray()
}

希望对你有帮助

Answer 2

你可以试试这个方法。更改此 onActivityResult。

if(requestCode == Gallery_Pick && resultCode == RESULT_OK && data != null) {
            try {
                Uri imageUri = imageReturnedIntent.getData();
                InputStream imageStream = getContentResolver().openInputStream(imageUri);
                Bitmap selectedImage = BitmapFactory.decodeStream(imageStream);

                selectedImage = getResizedBitmap(selectedImage, 400,300);// 400 and 300 height and width, replace with desired size

                imageView.setImageBitmap(selectedImage); // your desired image


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

这是您需要的 getResizedBitmap 方法。

    public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) {
    int width = bm.getWidth();
    int height = bm.getHeight();
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;

    // create a matrix for the manipulation
    Matrix matrix = new Matrix();

    // resize the bit map
    matrix.postScale(scaleWidth, scaleHeight);

    // recreate the new Bitmap
    Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);

    return resizedBitmap;
}