上传图片按比例压缩

protected void Button1_Click(object sender, EventArgs e)

{

//定义bool变量

bool Fileisvalid = false;

//判断上传了文件，并判断是否合乎要求

if (this.FileUpload1.HasFile)

{

//获取文件后缀名

string FileExtension = System.IO.Path.GetExtension(this.FileUpload1.FileName).ToLower();

//列出限制格式

string[] RestrictExtension ={ "jpg", "bmp", "gif", "png" };

//检测上传的图片格式

for (int i = 0; i < FileExtension.Length; i++)

{

if (FileExtension == RestrictExtension[i])

{

Fileisvalid = true;

}

}

if (Fileisvalid == true)

{

try

{

//定义最小宽度

int Min_Width = 200;

//显示图片1

this.Image1.ImageUrl = "~/images/" + FileUpload1.FileName;

//获取服务器的路径

string PathServer = Server.MapPath("~/images/" + FileUpload1.FileName);

//略缩的路径

this.FileUpload1.SaveAs(PathServer);

this.Label1.Text = this.FileUpload1.PostedFile.ContentLength + "字节";

//实例化img1

System.Drawing.Image img1 = System.Drawing.Image.FromFile(PathServer);

//按比例缩放高度

int Min_Height = Min_Width * img1.Height / img1.Width;

//生成按参数的图像

System.Drawing.Image img2 = img1.GetThumbnailImage(Min_Width, Min_Height, null, new System.IntPtr());

//新保存路径

string PathServer2 = Server.MapPath("~/images/" + "min_" + FileUpload1.FileName);

//保存到相应的路径

img2.Save(PathServer2, System.Drawing.Imaging.ImageFormat.Png);

Image3.ImageUrl = "~/images/" + "min_" + FileUpload1.FileName;

//释放资源

img1.Dispose();

img2.Dispose();

}

catch

{

Response.Redirect("../Error.aspx");

}

}

else

{

Label1.Text = "确认图片格式为jpg,gif,bmp,png格式.";

}

}



}



*因为技术不高，这个写了相当的久，逃了四节课才完成，呵呵。