net 把指定 URI 的资源下载到本地

 

            directoryinfo dir = new directoryinfo(appcontext.basedirectory);
            var path = dir.fullname + @"tempfile\";
            var filepath = path + guid.newguid() + filename;
            if (!directory.exists(path))
                directory.createdirectory(path);
            using (webclient client = new webclient())
            {
               // address：从中下载数据的 uri，www.xxxx.com/xx.jpg
               // filepath：从中下载数据的 uri，c:\\tempfile\\xx.jpg
                client.downloadfile(address, filepath);
            }