高分求！如何将已知的URL图片地址生成缩略图。。。
不是上传图片生成缩略图
如已知图片地址，http://img5.cache.netease.com/photo/0001/2012-07-02/900x600_85D2LU4300AO0001.jpg

按自定义宽高生成图片到本地。


------解决方案--------------------
string url = "http://img5.cache.netease.com/photo/0001/2012-07-02/900x600_85D2LU4300AO0001.jpg";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
//得到数据流
Stream streamReceive = response.GetResponseStream();

Bitmap bt = new Bitmap(System.Drawing.Image.FromStream(streamReceive),new Size(100,100));
bt.Save(@"E:\1.jpg");


楼主可以自己去测试一下。
------解决方案--------------------
public void MakeThumbnail(string imgPath_old, int width, int height)
{
  
System.Drawing.Image img = System.Drawing.Image.FromStream(new System.IO.MemoryStream(System.IO.File.ReadAllBytes(imgPath_old)));
 
int towidth = width; int toheight = height;
int x = 0; int y = 0; int ow = img.Width;
int oh = img.Height;
// 按值较大的进行等比缩放（不变形） 
if ((double)img.Width / (double)towidth < (double)img.Height / (double)toheight)
{
toheight = height;
towidth = img.Width * height / img.Height;
}
else
{
towidth = width;
toheight = img.Height * width / img.Width;
}
//新建一个bmp图片
System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
//新建一个画板
System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
//设置高质量插值法
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//清空画布并以透明背景色填充
g.Clear(System.Drawing.Color.Transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(img, new System.Drawing.Rectangle(0, 0, towidth, toheight),
new System.Drawing.Rectangle(x, y, ow, oh),
System.Drawing.GraphicsUnit.Pixel);

bitmap.Save(imgPath_old, System.Drawing.Imaging.ImageFormat.Jpeg);
bitmap.Dispose();
img.Dispose();
g.Dispose();
}
 
protected void Page_Load(object sender, EventArgs e)
{
String filePath = Server.MapPath("~/xxx.jpg");
new WebClient().DownloadFile("http://img5.cache.netease.com/photo/0001/2012-07-02/900x600_85D2LU4300AO0001.jpg",filePath );
MakeThumbnail(filePath , 100, 100);
}