asp.net上传图片压缩

转自csdn论坛,正确已经测试,非常好用。只不过引用的时候有点问题,图片没有释放,见下面红字部分。
我抄一份代码给你,清清月儿的.  
using System;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;

public class ImageThumbnail
{
   
public Image ResourceImage;
   
private int ImageWidth;
   
private int ImageHeight;
   
public string ErrorMessage;

   
public ImageThumbnail(string ImageFileName)
    {
        ResourceImage
= Image.FromFile(ImageFileName);
        ErrorMessage
= "";
    }

   
public bool ThumbnailCallback()
    {
       
return false;
    }


   
// 方法1,按大小
    public bool ReducedImage(int Width, int Height, string targetFilePath)
    {
       
try
        {
            Image ReducedImage;
            Image.GetThumbnailImageAbort callb
= new Image.GetThumbnailImageAbort(ThumbnailCallback);
            ReducedImage
= ResourceImage.GetThumbnailImage(Width, Height, callb, IntPtr.Zero);
            ReducedImage.Save(@targetFilePath, ImageFormat.Jpeg);
            ReducedImage.Dispose();
           
return true;
        }
       
catch (Exception e)
        {
            ErrorMessage
= e.Message;
           
return false;
        }
    }


   
// 方法2,按百分比  缩小60% Percent为0.6 targetFilePath为目标路径
    public bool ReducedImage(double Percent, string targetFilePath)
    {
       
try
        {
            Image ReducedImage;
            Image.GetThumbnailImageAbort callb
= new Image.GetThumbnailImageAbort(ThumbnailCallback);
            ImageWidth
= Convert.ToInt32(ResourceImage.Width * Percent);
            ImageHeight
= (ResourceImage.Height)*ImageWidth/ ResourceImage.Width;//等比例缩放
            ReducedImage = ResourceImage.GetThumbnailImage(ImageWidth, ImageHeight, callb, IntPtr.Zero);
            ReducedImage.Save(@targetFilePath, ImageFormat.Jpeg);
            ReducedImage.Dispose();
           
return true;
        }
       
catch (Exception e)
        {
            ErrorMessage
= e.Message;
           
return false;
        }
    }


}

后台代码:
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class _Default : System.Web.UI.Page
{

   
protected void Page_Load(object sender, EventArgs e)
    {

    }
   
protected void bt_upload_Click(object sender, EventArgs e)
    {
       
try
        {
           
if (FileUpload1.PostedFile.FileName == "")
            {
               
this.lb_info.Text = "请选择文件!";
            }
           
else
            {
               
string filepath = FileUpload1.PostedFile.FileName;
               
string filename = filepath.Substring(filepath.LastIndexOf("\\") + 1);
               
string serverpath1 = Server.MapPath("images/") + filename;
               
string serverpath2 = Server.MapPath("images/") + System.DateTime.Now.ToString("yyy-MM-dd-hh-mm-ss") + Session.SessionID + filename;
                FileUpload1.PostedFile.SaveAs(serverpath1);
                ImageThumbnail img
= new ImageThumbnail(filepath);
                img.ReducedImage(
0.4, serverpath2);//0.4表示缩小40%
                img.ResourceImage.Dispose(); //这里要释放一下
                this.lb_info.Text = "上传成功!";
            }
        }
       
catch (Exception error)
        {
           
this.lb_info.Text = "上传发生错误!原因:" + error.ToString();
        }
    }


}

原文地址:https://www.cnblogs.com/fogwang/p/2666580.html