您可以使用以下代码示例来实现在Android相机中拍摄图片并将其保存为多页PDF文件，然后通过上传到服务器：

1. 添加所需的权限到AndroidManifest.xml文件中：

2. 创建一个用于拍照的Activity，并在布局文件中添加一个按钮和一个ImageView：

public class CameraActivity extends AppCompatActivity {

    private static final int REQUEST_IMAGE_CAPTURE = 1;
    private ImageView imageView;
    private Button captureButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);

        imageView = findViewById(R.id.imageView);
        captureButton = findViewById(R.id.captureButton);

        captureButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dispatchTakePictureIntent();
            }
        });
    }

    private void dispatchTakePictureIntent() {
        Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
            startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
        }
    }

    @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);
            savePdf(imageBitmap);
        }
    }

    private void savePdf(Bitmap bitmap) {
        PdfDocument document = new PdfDocument();
        PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(bitmap.getWidth(), bitmap.getHeight(), 1).create();
        PdfDocument.Page page = document.startPage(pageInfo);
        Canvas canvas = page.getCanvas();
        Paint paint = new Paint();
        paint.setColor(Color.parseColor("#ffffff"));
        canvas.drawPaint(paint);
        canvas.drawBitmap(bitmap, 0, 0, null);
        document.finishPage(page);

        String filePath = Environment.getExternalStorageDirectory() + "/my_pdf.pdf";
        File file = new File(filePath);
        try {
            document.writeTo(new FileOutputStream(file));
            document.close();
            uploadFile(file);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void uploadFile(File file) {
        // 通过上传到服务器的逻辑
        // 在这里实现上传文件到服务器的代码
    }
}

3. 在res/layout文件夹中创建一个名为activity_camera.xml的布局文件：

这样，当用户点击Capture按钮时，将会打开相机进行拍照，并将拍摄的图片保存为多页PDF文件。然后，通过uploadFile方法将PDF文件上传到服务器。您需要根据您的服务器端实现来编写相应的上传代码。