Asp.NET 上传图片并生成缩略图
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;
using System.Data.SqlClient;
using System.IO; //注意把这个加上
using System.Drawing; //注意把这个加上
public partial class PhotoPage : System.Web.UI.Page
{
SqlConnection sqlCon = new SqlConnection("");
SqlCommand sqlCom = new SqlCommand();
protected void Page_Load(object sender, EventArgs e)
{
}
//生成图片代码
protected void btnOK_Click(object sender, EventArgs e)
{
string P_str_filePath = ""; //定义一个在客户端文件的路径的变量
string P_str_fileExtName = "", P_str_mFileName, P_str_mPath;//文件的扩展名
System.Text.StringBuilder strMsg = new System.Text.StringBuilder("上传图片;<hr color=red>");
if (fileUp .PostedFile.FileName!="") //fileUp是控件fileload控件的名称 这句是取控件的文件名称
{
P_str_filePath = fileUp.PostedFile.FileName; //获取图片路径
P_str_fileExtName = P_str_filePath.Substring(P_str_filePath.LastIndexOf(".")+1); //获取扩展名
try
{
P_str_mPath = Server.MapPath("Images/Pictures/"); //获取服务器端的文件的路径
P_str_mFileName = P_str_filePath.Substring(P_str_filePath.LastIndexOf("\\") + 1); //获取文件的名称
fileUp.PostedFile.SaveAs(P_str_mPath + P_str_mFileName); //保存到制定的路径下
//生成缩略图
string smallFileName = Server.MapPath("Images/SmallPictures/")+P_str_mFileName; //上传缩略图的路径
System.Drawing . Image smallImage = System.Drawing .Image.FromStream(fileUp.PostedFile.InputStream, true); //从文件中取出图片对象
double width = Double.Parse(TextBox1.Text .ToString ()); //设定的高度和宽度
double height = Double.Parse(TextBox2.Text .ToString ());
double NewWidth, NewHeight; //新的高度和宽度
if (smallImage.Width > smallImage.Height)
{
NewWidth = width;
NewHeight = smallImage.Height * (NewWidth / smallImage.Width);
}
else
{
NewHeight = height;
NewWidth=smallImage.Width*(NewHeight/smallImage.Height);
}
if (NewHeight > height)
{
NewHeight = height;
}
if (NewWidth > width)
{
NewWidth = width;
}
Size size= new Size((int)NewWidth, (int)NewHeight); //图片的大小
System.Drawing. Image Bitmap = new System.Drawing. Bitmap(size.Width, size.Height); //新生成一个bitmap对象
Graphics graphics = Graphics.FromImage(Bitmap); //新生成的画板
graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置最高的质量
graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //设置高质量,低速度呈现平滑程度
graphics.Clear(Color.White); //清空画布
//在指定位置画图
graphics.DrawImage(smallImage, new System.Drawing.Rectangle(0, 0, Bitmap.Width, Bitmap.Height),
new System.Drawing.Rectangle(0, 0,smallImage.Width,smallImage.Height),
System.Drawing.GraphicsUnit.Pixel);
//文字水印
System.Drawing.Graphics textGraphics = System.Drawing.Graphics.FromImage(Bitmap);
System.Drawing.Font font = new Font("宋体", 10);
System.Drawing.Brush brush = new SolidBrush(Color.Black);
textGraphics.DrawString(TextBox3.Text.Trim(), font, brush, 10, 10);
textGraphics.Dispose();
///图片水印
//System.Drawing.Image copyImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath("pic/1.gif"));
//Graphics a = Graphics.FromImage(Bitmap);
//a.DrawImage(copyImage, new Rectangle(Bitmap.Width - copyImage.Width, Bitmap.Height - copyImage.Height, copyImage.Width, copyImage.Height),
0, 0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);
//保存缩略图
try
{
Bitmap.Save(smallFileName, System.Drawing.Imaging.ImageFormat.Gif);
}
catch (Exception ex)
{
Response.Write("保存缩略图失败:" + ex.Message);
}
string imageUrl = ""; //定义一个用来存储图片url的变量
Image1.ImageUrl =smallFileName .Substring( smallFileName.IndexOf("));
imageUrl=smallFileName .Substring( smallFileName.IndexOf("));
Image1.ImageUrl ="~"+ imageUrl.Replace("\\", "/");
graphics.Dispose();
smallImage.Dispose();
Bitmap.Dispose();
//copyImage.Dispose();
//a.Dispose();
//copyImage.Dispose();
}
catch
{
}
}
}