C# 生成好看的验证码

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网站登录总是会用到验证码，生成验证码对于C#来说很简单，我用的是一般处理程序来写的验证码。具体代码如下：

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Web;

namespace UI.ajax
{
/// <summary>
/// code 的摘要说明
/// </summary>
public class code : IHttpHandler
{
/// <summary>
/// 验证码类型(0-字母数字混合,1-数字,2-字母)
/// </summary>
private string validateCodeType = "0";
public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = "text/plain";
context.Response.BufferOutput = true;
context.Response.Cache.SetExpires(DateTime.Now.AddMilliseconds(-1));
context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
context.Response.AppendHeader("Pragma", "No-Cache");
string ValidateCode = GenerateCheckCode();
//context.Session["CheckCode"] = ValidateCode;//将字符串保存到Session中，以便需要时进行验证
CreateCheckCodeImage(context, ValidateCode);
}
public void CreateCheckCodeImage(HttpContext context, string checkCode)
{

int randAngle = 40; //随机转动角度
int mapwidth = (int)(checkCode.Length * 18);
Bitmap map = new Bitmap(mapwidth, 24);//创建图片背景
Graphics graph = Graphics.FromImage(map);
graph.Clear(Color.White);//清除画面，填充背景
graph.DrawRectangle(new Pen(Color.LightGray, 0), 0, 0, map.Width - 1, map.Height - 1);//画一个边框

Random rand = new Random();

//验证码旋转，防止机器识别
char[] chars = checkCode.ToCharArray();//拆散字符串成单字符数组
//文字距中
StringFormat format = new StringFormat(StringFormatFlags.NoClip);
format.Alignment = StringAlignment.Center;
format.LineAlignment = StringAlignment.Center;
//定义颜色
Color[] c = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.DarkBlue };

//画图片的背景噪音线
for (int i = 0; i < 2; i++)
{
int x1 = rand.Next(10);
int x2 = rand.Next(map.Width - 10, map.Width);
int y1 = rand.Next(map.Height);
int y2 = rand.Next(map.Height);

graph.DrawLine(new Pen(c[rand.Next(7)]), x1, y1, x2, y2);
}

for (int i = 0; i < chars.Length; i++)
{
int cindex = rand.Next(7);
int findex = rand.Next(5);
Font f = new System.Drawing.Font("Arial", 18, System.Drawing.FontStyle.Regular);//字体样式(参数2为字体大小)
Brush b = new System.Drawing.SolidBrush(c[cindex]);
Point dot = new Point(12, 16);
float angle = rand.Next(-randAngle, randAngle);//转动的度数
graph.TranslateTransform(dot.X, dot.Y);//移动光标到指定位置
graph.RotateTransform(angle);
graph.DrawString(chars[i].ToString(), f, b, 1, 1, format);
graph.RotateTransform(-angle);//转回去
graph.TranslateTransform(2, -dot.Y);//移动光标到指定位置
}
//生成图片
System.IO.MemoryStream ms = new System.IO.MemoryStream();
map.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
context.Response.ClearContent();
context.Response.ContentType = "image/gif";
context.Response.BinaryWrite(ms.ToArray());
graph.Dispose();
map.Dispose();
}
private string GenerateCheckCode()
{
int number;
char code;
string checkCode = String.Empty;
System.Random random = new Random();
for (int i = 0; i < 4; i++)
{
number = random.Next();
code = (char)(‘0‘ + (char)(number % 10));
if (number % 2 == 0)
code = (char)(‘0‘ + (char)(number % 10));
else
code = (char)(‘A‘ + (char)(number % 26));
//去掉0,O,I,o,i,Z,z
if (code.ToString() == "O" || code.ToString() == "I" || code.ToString() == "o" || code.ToString() == "i" || code.ToString() == "Z" || code.ToString() == "z")
{
i--;
continue;
}
//要求全为数字
if (validateCodeType == "1")
{
if ((int)code < 48 || (int)code > 57)
{
i--;
continue;
}
}
//要求全为字母
if (validateCodeType == "2")
{
if ((int)code > 47 || (int)code < 58)
{
i--;
continue;
}
}
checkCode += code.ToString();
}
return checkCode;
}

public bool IsReusable
{
get
{
return false;
}
}
}
}

具体效果为:

C# 生成好看的验证码

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原文地址：http://www.cnblogs.com/0208wky/p/4738700.html