1、上传图片加水印：

 

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
             
     
    
      
        
               
               
           
      
    
     

 

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Drawing;public partial class _Default : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        Button1.Click += Button1_Click;    }    void Button1_Click(object sender, EventArgs e)    {        //获得要上传的图片        System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.FileContent);        //加上水印        Graphics g = Graphics.FromImage(img);        string s="hello word";        Font f=new Font("微软雅黑",30);        Brush b=new SolidBrush(Color.Red);        PointF pf=new PointF(50,50);        g.DrawString(s,f,b,pf);        //保存下来        string path = "upload/" +DateTime.Now.ToString("yyyyMMddhhmmssms")+ FileUpload1.FileName;        img.Save(Server.MapPath(path));        Image1.ImageUrl = path;    }}

2、验证码制作

 

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
             
     
            
              
              
              
              
              
     

 

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Drawing;public partial class Default2 : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {               Button1.Click += Button1_Click;    }    void Button1_Click(object sender, EventArgs e)    {        Label1.Text = Session["Default2"].ToString();        if (TextBox1.Text == Session["Default2"].ToString())        {            Label2.Text = "正确！！！";        }        else { Label2.Text = "错误！！"; }    }}

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="yzm.aspx.cs" Inherits="yzm" %>
             
     
    
      
        
      
    
     

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Drawing;public partial class yzm : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        List
     
       clist = new List
      
       ();        clist.Add(Color.Red);        clist.Add(Color.Purple);        clist.Add(Color.Pink);        clist.Add(Color.Blue);        clist.Add(Color.Orange);        clist.Add(Color.Black);        clist.Add(Color.White);        clist.Add(Color.Violet);        Random r = new Random();        string s = "";        string all = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";        for (int i = 0; i < 4; i++)        {            s += all.Substring(r.Next(0, all.Length), 1);        }        Session["Default2"] = s;        Bitmap img = new Bitmap(100, 50);        Graphics g = Graphics.FromImage(img);        Brush b = new SolidBrush(clist[r.Next(0, clist.Count)]);        g.FillRectangle(b, 0, 0, 100, 50);        Graphics g2 = Graphics.FromImage(img);        Font f = new Font("微软雅黑", 30);        Brush b2 = new SolidBrush(Color.Red);        PointF pf = new PointF(5, 5);        g2.DrawString(s, f, b2, pf);        for (int i = 0; i < 7; i++)        {            Graphics g3 = Graphics.FromImage(img);            Pen p3 = new Pen(new SolidBrush(clist[r.Next(0, clist.Count)]), r.Next(2, 5));            g3.DrawLine(p3, new Point(r.Next(0, 100), r.Next(0, 50)), new Point(r.Next(0, 100), r.Next(0, 50)));        }        img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Png);    }}