把bitmap转成文件存入APP项目目录

 //把bitmap转成file
    public File getFile(Bitmap bitmap) {

        File file = new File(getFilesDir(), "payCode.png");

        try {
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bos);
            bos.flush();
            bos.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return file;
    }