标签：
水印：一个fileupload一个button
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.IO;
public partial class 水印 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void shangchuan_Click(object sender, EventArgs e)
{
//一、从上传数据中，转化成图片对象。
Stream s = FileUpload1.FileContent;
System.Drawing.Image img = System.Drawing.Image.FromStream(s);//重点
//二、对图片对象进行画水印
//1.造笔
SolidBrush brush=new SolidBrush (Color.Yellow);
//2.造字体
Font f = new Font("Buxton Sketch", 12);
//3.找到图像绘图区域
Graphics gs = Graphics.FromImage(img);
//4.确定开始画位置
float x = 0, y = 0;
SizeF size = gs.MeasureString("happy new year!", f);//确定书写的水印（即要写的字）的大小
x = img.Width-size.Width;
y = img.Height-size.Height;
//5.开始画
gs.DrawString("happy new year!", f, brush, x, y);
//三、图片对象另存到硬盘上去
string app = FileUpload1.FileName;
string path = Server.MapPath("/upload/")+app;
img.Save(path);
}
}
验证码：
显示页面（出现验证码，cs代码中夹杂验证码的验证）：
aspx页面（script中是点击验证码后改变原来的随机数）：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Denglu.aspx.cs" Inherits="Denglu" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<script language="javascript">
function Bianhua()
{
var img = document.getElementById("Image1");
img.setAttribute("src", "验证码.aspx?id=" + Math.random());
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Image ID="Image1" runat="server" ImageUrl="验证码.aspx" onclick="Bianhua()"/>
<br />
<asp:Button ID="Deng" runat="server" Text="登录" />
</div>
</form>
</body>
</html>
验证码的生成图片页面：
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.Drawing;
using System.IO;
public partial class 验证码 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Bitmap img = new Bitmap(70, 30);//创建一个新的位图
string suijishu = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM1234567890";
//所有随机产生的字符的集合字符串
Random ran = new Random();
string yzm = "";
for (int i = 0; i < 4; i++)
{
int a = ran.Next(suijishu.Length);
yzm += suijishu.Substring(a,1);
}
//以上是产生4个随机的字符组成一个拥有4个字符的字符串
Session["code"] = yzm;
//将随机产生的字符串记录下来，供用户填写时验证
//、、、以下是将产生的字符串水印到产生的位图上，（由于位图默认背景颜色为黑色)
SolidBrush brush = new SolidBrush(Color.Green);//勾勒画笔颜色
Font fo = new Font("SketchFlow Print", 18);//描述字体以及大小
Graphics gs = Graphics.FromImage(img);//描述要水印的图片，即新产生的位图
gs.DrawString(yzm, fo, brush, 0, 0);//勾画水印
//把图片保存到输出流中去
img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
Response.End();
}
}
或者验证码的背景图片为白色：
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)
{
//造一个图片
Bitmap img = new Bitmap(60, 30);
//生成个随机数
string str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
Random rand = new Random();
string code = "";
for (int i = 0; i < 4; i++)
{
int start = rand.Next(str.Length);
code += str.Substring(start, 1);
}
Session["yzm"] = code;
//把随机数画到图片上
SolidBrush brush = new SolidBrush(Color.White);
Font font = new Font("Lucida Sans Unicode", 14);
Graphics g = Graphics.FromImage(img);
//a.把图片背景涂白
g.FillRectangle(brush, 0, 0, 60, 30);
//b.给画笔换个颜色
brush.Color = Color.Red;
g.DrawString(code, font, brush, 0, 0);
//把图片保存到输出流中去
img.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
Response.End();
}
}
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原文地址：http://www.cnblogs.com/xianshui/p/4541977.html
