使上传的图片在 layout/Activity 更改后保留

Question

我在 java 和 android 编程方面仍然是个新手，我相信我在过去几周已经取得了很大进展，但现在我有点卡住了，我真的很感激你的帮助。

我正在尝试开发一个可以创建用户个人资料布局的应用程序。到目前为止，我已准备就绪，可以从 Web 服务中提取用户数据。但现在我必须为用户添加一种从画廊或相机上传照片的方式。到目前为止，我已经通过下一个代码实现了这一点：

public void loadimage (View view)
{
    Intent intent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    startActivityForResult(intent, 0);
}

public void onActivityResult(int requestCode, int resultCode, Intent data)
{
    super.onActivityResult(requestCode, resultCode, data);

    if (resultCode ==  RESULT_OK)
    {
        Uri targetUri = data.getData();
        picture_location = targetUri.toString();
        textTargetUri.setText(picture_location);
        Bitmap bitmap;
        try
        {
            bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(targetUri));
            targetImage.setImageBitmap(bitmap);
        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        }
    }
}

这确实适用于从厨房绘制图像并在屏幕上显示路径文件（好吧，这不会成为我的最终版本）但是，当我输入另一个 layout/activity 时，加载的图片消失了，我必须重新上传。我正在尝试下一个保存方法：

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState)
{
    image = savedInstanceState.getParcelable("BitmapImage");
    targetImage.setImageBitmap(image);
    textTargetUri.setText(savedInstanceState.getString("path_to_picture"));
}

@Override
public void onSaveInstanceState (Bundle savedInstanceState)
{
    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putParcelable("BitmapImage", bitmap);
    savedInstanceState.putString("path_to_picture", picture_location);
}

但是，这仅适用于屏幕方向更改，不适用于 layout/activity 更改。有没有办法让上传的图片即使 activity 发生变化也能保留？我的服务器在内存方面非常小，所以上传到它不是一个好的选择，我必须将它保存在本地。请帮助:(

Answer 1

试试这两种方法：

首先，向他们展示 select 选项的对话框：

private void selectImage() {
    final CharSequence[] items = { getString(R.string.take_photo), getString(R.string.choose_from_gallery),
            getString(R.string.cancel) };

    AlertDialog.Builder builder = new AlertDialog.Builder(MyAccountActivity.this);
    builder.setTitle(getString(R.string.upload_photo));
    builder.setItems(items, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int item) {
            if (items[item].equals(getString(R.string.take_photo))) {
                Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                startActivityForResult(intent, REQUEST_CAMERA);
            } else if (items[item].equals(getString(R.string.choose_from_gallery))) {
                Intent intent = new Intent(
                        Intent.ACTION_PICK,
                        android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                intent.setType("image/*");
                startActivityForResult(
                        Intent.createChooser(intent, getString(R.string.select_file)),
                        SELECT_FILE);
            } else if (items[item].equals(getString(R.string.choose_from_gallery))) {
                dialog.dismiss();
            }
        }
    });
    builder.show();
}

当用户拍照或select从图库中编辑时接收实际图像：

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

    if (resultCode == Activity.RESULT_OK) {
        if (requestCode == SELECT_FILE)
            onSelectFromGalleryResult(data);
        else if (requestCode == REQUEST_CAMERA)
            onCaptureImageResult(data);
        else if (requestCode == Crop.REQUEST_CROP) {
            handleCrop(resultCode, data);
        }
    }
}

接下来是根据需要处理裁剪 - 这不是运行此代码所必需的，但您可以使用它；

private void onCaptureImageResult(Intent data) {

    beginCrop(data.getData());
}

@SuppressWarnings("deprecation")
private void onSelectFromGalleryResult(Intent data) {
    Uri selectedImageUri = data.getData();

    beginCrop(selectedImageUri);
}

private void beginCrop(Uri source) {
    Uri destination = Uri.fromFile(new File(getCacheDir(), "cropped"));
    Crop.of(source, destination).asSquare().start(this);
}

private void handleCrop(int resultCode, Intent result) {
    if (resultCode == RESULT_OK) {

        try {
            Bitmap bitmap = handleSamplingAndRotationBitmap(this, Crop.getOutput(result));

            saveToInternalStorage(bitmap);

            mUserProfilePhoto.setImageBitmap(readFromInternalStorage("profile.png"));
        }catch (IOException e){ /* do nothing here */}
    } else if (resultCode == Crop.RESULT_ERROR) {
        Toast.makeText(this, Crop.getError(result).getMessage(), Toast.LENGTH_SHORT).show();
    }
}

有时，如果图像不是直立的，您可能想要旋转它：

private static Bitmap handleSamplingAndRotationBitmap(Context context, Uri selectedImage) throws IOException {
    int MAX_HEIGHT = 1024;
    int MAX_WIDTH = 1024;

    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    InputStream imageStream = context.getContentResolver().openInputStream(selectedImage);
    BitmapFactory.decodeStream(imageStream, null, options);
    imageStream.close();

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, MAX_WIDTH, MAX_HEIGHT);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    imageStream = context.getContentResolver().openInputStream(selectedImage);
    Bitmap img = BitmapFactory.decodeStream(imageStream, null, options);

    img = rotateImageIfRequired(img, selectedImage);
    return img;
}

private static int calculateInSampleSize(BitmapFactory.Options options,
                                         int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        // Calculate ratios of height and width to requested height and width
        final int heightRatio = Math.round((float) height / (float) reqHeight);
        final int widthRatio = Math.round((float) width / (float) reqWidth);

        // Choose the smallest ratio as inSampleSize value, this will guarantee a final image
        // with both dimensions larger than or equal to the requested height and width.
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;

        // This offers some additional logic in case the image has a strange
        // aspect ratio. For example, a panorama may have a much larger
        // width than height. In these cases the total pixels might still
        // end up being too large to fit comfortably in memory, so we should
        // be more aggressive with sample down the image (=larger inSampleSize).

        final float totalPixels = width * height;

        // Anything more than 2x the requested pixels we'll sample down further
        final float totalReqPixelsCap = reqWidth * reqHeight * 2;

        while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
            inSampleSize++;
        }
    }
    return inSampleSize;
}

private static Bitmap rotateImageIfRequired(Bitmap img, Uri selectedImage) throws IOException {

    ExifInterface ei = new ExifInterface(selectedImage.getPath());
    int orientation = ei.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);

    switch (orientation) {
        case ExifInterface.ORIENTATION_ROTATE_90:
            return rotateImage(img, 90);
        case ExifInterface.ORIENTATION_ROTATE_180:
            return rotateImage(img, 180);
        case ExifInterface.ORIENTATION_ROTATE_270:
            return rotateImage(img, 270);
        default:
            return img;
    }
}

private static Bitmap rotateImage(Bitmap img, int degree) {
    Matrix matrix = new Matrix();
    matrix.postRotate(degree);
    Bitmap rotatedImg = Bitmap.createBitmap(img, 0, 0, img.getWidth(), img.getHeight(), matrix, true);
    img.recycle();
    return rotatedImg;
}

用于在用户从图库中选择或从相机拍摄时立即存储：

private boolean saveToInternalStorage(Bitmap image) {

    try {
        FileOutputStream fos = this.openFileOutput("profile.png", Context.MODE_PRIVATE);

        image.compress(Bitmap.CompressFormat.PNG, 100, fos);
        fos.close();

        return true;
    } catch (Exception e) {
        return false;
    }
}

现在从存储中读取：

private Bitmap readFromInternalStorage(String filename){
    try {
        File filePath = this.getFileStreamPath(filename);
        FileInputStream fi = new FileInputStream(filePath);
        return BitmapFactory.decodeStream(fi);
    } catch (Exception ex) { /* do nothing here */}

    return null;
}

在 onResume 中，我有这段代码可以将图像设置为 imageview：

@Override
public void onResume(){
    super.onResume();

    Bitmap savedProfilePhoto = readFromInternalStorage("profile.png");

    if (savedProfilePhoto != null){
        mUserProfilePhoto.setImageBitmap(savedProfilePhoto);
    }
}

这里差不多完成了：

将此添加到您的依赖项中 (build.gradle)

dependencies{
     compile 'com.soundcloud.android:android-crop:1.0.1@aar'
 }

最后，在您的 android 清单文件中，要使裁剪库起作用，请添加：

<activity android:name="com.soundcloud.android.crop.CropImageActivity"/>

这就是您在应用程序中启用select从图库中获取图像或使用相机拍照所需要的全部内容！

希望这对您和其他有需要的人有所帮助，祝您好运！

使上传的图片在 layout/Activity 更改后保留

Make uploaded image remain after layout/Activity change

java

android

imageview

onactivityresult

android-savedstate