C#之ASP.NET简单图片上传+水印+缩略图

水印.jpg

WebFormUpload.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebFormUpload.aspx.cs" Inherits="Study.WebFormUpload" %>






    


    

        
        
        
        
    

WebFormUpload.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Drawing;

namespace Study
{
    public partial class WebFormUpload : System.Web.UI.Page
    {
        //目录
        public string Dir { get; set; }
        //上传文件的完整路径
        public string FullDir { get; set; }
        //获取要添加的水印文字
        public string WaterName  { get; set; }

        protected void Page_Load(object sender, EventArgs e)
        {
            //HttpFileCollection httpFileCollection = Request.Files;
            
            if (!string.IsNullOrEmpty(Request.Form["isPostBack"]))
            {
                this.WaterName = Request.Form["waterName"];
                SaveFile();
                MakeWaterImage(Dir,FullDir,WaterName);
                MakeThumbnailImage(Dir,FullDir,300, 200);
            }
        }

        protected void SaveFile()
        {
            
            HttpPostedFile file = Request.Files[0];
            if (file.ContentLength>0)
            {
                //对上传的文件类型进行校验
                string fileName = Path.GetFileName(file.FileName);//获取上传文件的名称，包含扩展名
                string fileExt = Path.GetExtension(fileName);//获取上传文件扩展名
                List Extension = new List()
                {
                    ".jpg",
                    ".png",
                    ".bmp",
                    ".gif",
                    ".jpeg"
                };
                if (Extension.Contains(fileExt))
                {
                    //1.对上传文件进行重命名
                    string newFileName = Guid.NewGuid().ToString();
                    //2.将上传的文件放在不同目录下
                    this.Dir = "upload/" + DateTime.Now.Year + "/" + DateTime.Now.Month + "/" + DateTime.Now.Day + "/";
                    //创建文件夹
                    if (!Directory.Exists(Request.MapPath(this.Dir)))
                    {
                        Directory.CreateDirectory(Request.MapPath(this.Dir));
                    }
                    this.FullDir = this.Dir + newFileName + fileExt;//文件存放的完整路径
                    file.SaveAs(Request.MapPath(FullDir));//保存原始文件
                }
                else
                {
                    Response.Write("只能上传图片文件");
                }
            }
            else
            {
                Response.Write("请选择上传文件");
            }
        }
        protected void MakeWaterImage(string dir,string fullDir,string waterName)
        {
            //创建图片水印
            using (System.Drawing.Image img = System.Drawing.Image.FromFile(Request.MapPath(fullDir)))
            {
                using (Bitmap map = new Bitmap(img.Width, img.Height)) //根据图片的高度和宽度创建画布
                {
                    using (Graphics g = Graphics.FromImage(map))
                    {
                        //先用画笔在画布上画图，从画布的左上角开始画，画图大小是上传图片的大小
                        g.DrawImage(img, 0, 0, img.Width, img.Height);
                        //再用画笔在画面上画文字水印
                        g.DrawString(WaterName, new Font("微软雅黑", 15.0f, FontStyle.Regular), Brushes.Red, new PointF(img.Width / 2, img.Height / 3));
                        string waterImageName = "WaterMark-" + Guid.NewGuid().ToString();
                        //保存水印图片
                        map.Save(Request.MapPath(dir + waterImageName + ".jpg"), System.Drawing.Imaging.ImageFormat.Jpeg);
                        //展示水印图片
                        Response.Write("![]("+dir + waterImageName + ".jpg)");
                    }
                }
            }
        }
        protected void MakeThumbnailImage(string dir,string fullDir,int width,int height)
        {

            //创建缩略图
            using (System.Drawing.Image img = System.Drawing.Image.FromFile(Request.MapPath(fullDir)))
            {
                using (Bitmap map = new Bitmap(width, height))
                {
                    using (Graphics g = Graphics.FromImage(map))
                    {
                        g.DrawImage(img, 0, 0, map.Width, map.Height);
                        string thumbnailFileName = "Thumbnail-" + Guid.NewGuid().ToString();
                        map.Save(Request.MapPath(dir + thumbnailFileName + ".jpg"), System.Drawing.Imaging.ImageFormat.Jpeg);
                        Response.Write("![](" + dir + thumbnailFileName + ".jpg)");
                    }
                }
            }
        }
    }
}