//本地不存在,则下载并保存在本地
var http = new FrameWork.Helper.HttpHelper();//公司封DLL
using (var stream = http.GetFile(url, 1024))
{
stream.Position = 0;//加入这么代码 还原位置就可以了
Image bt = Bitmap.FromStream(stream);
pic_url.Image = bt;
if (!Directory.Exists(dir))
{
Directory.CreateDirectory(dir);
}
bt.Save(localpath, ImageFormat.Jpeg);
参考了这个文章
https://blog.youkuaiyun.com/qq_32250495/article/details/50925592