.net实现验证码功能 - 飛雪飄寒

　　验证码功能一般是用于防止批量注册的，不少网站为了防止用户利用机器人自动注册、登录、灌水，都采用了验证码技术。所谓验证码，就是将一串随机产生的数字或字母或符号或文字，生成一幅图片，图片里加上一些干扰象素（防止OCR），由用户肉眼识别其中的验证码信息，输入表单提交网站验证，验证成功后才能使用某项功能。

　　一、验证码简介

　　常见的验证码有如下几种：

　　1、纯数字验证码，一般为四位随机数字；

　　2、数字+字母验证码，一般从数字（0~9）和字母(A~Z和a~z)中随机抽出几个字符组成；

　　3、汉字验证码，相对而言，这种验证码比较少见一点，实现起来也相对复杂一些，但在不少网站中还是可以看到的；

　　二、验证码的实现

　　1、纯数字验证码的实现

　　纯数字验证码的实现相对比较简单，可通过以下两种方法来实现

　　（1）使用随机数方式，代码如下：　

private String GetRandomint(int codeCount)

{

Random random = new Random();

string min = "";

string max = "";

for (int i = 0; i < codeCount; i++)

{

min +="1";

max+="9";

}

return (random.Next(Convert.ToInt32(min),Convert.ToInt32(max)).ToString());

}

　　(2)使用随机组合方式，代码如下：

private string CreateRandomCode(int codeCount)

{

string allChar = "0,1,2,3,4,5,6,7,8,9";

string[] allCharArray = allChar.Split(\',\');

string randomCode = "";

int temp = -1;

Random rand = new Random();

for (int i = 0; i < codeCount; i++)

{

if (temp != -1)

{

rand = new Random(i * temp * ((int)DateTime.Now.Ticks));

}

int t = rand.Next(9);

if (temp == t)

{

return CreateRandomCode(codeCount);

}

temp = t;

randomCode += allCharArray[t];

}

return randomCode;

}

　　2、数字+字母验证码的实现，代码如下：

private string CreateRandomCode(int codeCount)

{

string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";

string[] allCharArray = allChar.Split(\',\');

string randomCode = "";

int temp = -1;

Random rand = new Random();

for (int i = 0; i < codeCount; i++)

{

if (temp != -1)

{

rand = new Random(i * temp * ((int)DateTime.Now.Ticks));

}

int t = rand.Next(61);

if (temp == t)

{

return CreateRandomCode(codeCount);

}

temp = t;

randomCode += allCharArray[t];

}

return randomCode;

}

　　3、汉字验证码的实现，代码如下：

/**/

此函数在汉字编码范围内随机创建含两个元素的十六进制字节数组，每个字节数组代表一个汉字，并将

四个字节数组存储在object数组中。

参数：strlength，代表需要产生的汉字个数

public static object[] CreateRegionCode(int strlength)

{

//定义一个字符串数组储存汉字编码的组成元素

string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

Random rnd = new Random();

//定义一个object数组用来

object[] bytes = new object[strlength];

/**/

/*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中

每个汉字有四个区位码组成

区位码第1位和区位码第2位作为字节数组第一个元素

区位码第3位和区位码第4位作为字节数组第二个元素

for (int i = 0; i < strlength; i++)

{

//区位码第1位

int r1 = rnd.Next(11, 14);

string str_r1 = rBase[r1].Trim();

//区位码第2位

rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机数发生器的种子避免产生重复值

int r2;

if (r1 == 13)

{

r2 = rnd.Next(0, 7);

}

else

{

r2 = rnd.Next(0, 16);

}

string str_r2 = rBase[r2].Trim();

//区位码第3位

rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);

int r3 = rnd.Next(10, 16);

string str_r3 = rBase[r3].Trim();

//区位码第4位

rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);

int r4;

if (r3 == 10)

{

r4 = rnd.Next(1, 16);

}

else if (r3 == 15)

{

r4 = rnd.Next(0, 15);

}

else

{

r4 = rnd.Next(0, 16);

}

string str_r4 = rBase[r4].Trim();

//定义两个字节变量存储产生的随机汉字区位码

byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);

byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);

//将两个字节变量存储在字节数组中

byte[] str_r = new byte[] { byte1, byte2 };

//将产生的一个汉字的字节数组放入object数组中

bytes.SetValue(str_r, i);

}

return bytes;

}

　　三、具体实例　

　　(实例1)　

前台代码display.aspx

<body>

<div>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:Image ID="Image1" runat="server" ImageUrl="png.aspx" /><br />

<br />

<asp:Button ID="Button2" runat="server" OnClick="Button2_Click" Text="Button" />

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">

<asp:ListItem Value="3">默认</asp:ListItem>

<asp:ListItem Value="1">文字</asp:ListItem>

<asp:ListItem Value="2">数字</asp:ListItem>

<asp:ListItem Value="3">混合</asp:ListItem>

</asp:DropDownList></div>

</form>

</body>

后台代码display.cs

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)

{

switch (DropDownList1.SelectedValue)

{

case "1":

Image1.ImageUrl = "png.aspx?aa=1";

break;

case "2":

Image1.ImageUrl = "png.aspx?aa=2";

break;

case "3":

Image1.ImageUrl = "png.aspx?aa=3";

break;

}

protected void Button2_Click(object sender, EventArgs e)

{

if (TextBox1.Text == Session["gif"].ToString())

Response.Write("OK,正确");

else

Response.Write("验证码不符合");

}

后台代码png.cs

public partial class png : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

switch (Request.QueryString["aa"])

{

case "1":

gif = stxt(10);

Session["gif"] = stxt(10);

break;

case "2":

gif = GetRandomint(4);

Session["gif"] = GetRandomint(4);

break;

case "3":

gif = CreateRandomCode(4);

Session["gif"] = CreateRandomCode(4);

break;

default:

gif = CreateRandomCode(4);

Session["gif"] = CreateRandomCode(4);

break;

}

CreateImage(Session["gif"].ToString());

}

private String GetRandomint(int codeCount)

{

Random random = new Random();

string min = "";

string max = "";

for (int i = 0; i < codeCount; i++)

{

min +="1";

max+="9";

}

return (random.Next(Convert.ToInt32(min),Convert.ToInt32(max)).ToString());

}

/**/

此函数在汉字编码范围内随机创建含两个元素的十六进制字节数组，每个字节数组代表一个汉字，并将

四个字节数组存储在object数组中。

参数：strlength，代表需要产生的汉字个数

public static object[] CreateRegionCode(int strlength)

{

//定义一个字符串数组储存汉字编码的组成元素

string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

Random rnd = new Random();

//定义一个object数组用来

object[] bytes = new object[strlength];

/**/

/*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中

每个汉字有四个区位码组成

区位码第1位和区位码第2位作为字节数组第一个元素

区位码第3位和区位码第4位作为字节数组第二个元素

for (int i = 0; i < strlength; i++)

{

//区位码第1位

int r1 = rnd.Next(11, 14);

string str_r1 = rBase[r1].Trim();

//区位码第2位

rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机数发生器的种子避免产生重复值

int r2;

if (r1 == 13)

{

r2 = rnd.Next(0, 7);

}

else

{

r2 = rnd.Next(0, 16);

}

string str_r2 = rBase[r2].Trim();

//区位码第3位

rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);

int r3 = rnd.Next(10, 16);

string str_r3 = rBase[r3].Trim();

//区位码第4位

rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);

int r4;

if (r3 == 10)

{

r4 = rnd.Next(1, 16);

}

else if (r3 == 15)

{

r4 = rnd.Next(0, 15);

}

else

{

r4 = rnd.Next(0, 16);

}

string str_r4 = rBase[r4].Trim();

//定义两个字节变量存储产生的随机汉字区位码

byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);

byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);

//将两个字节变量存储在字节数组中

byte[] str_r = new byte[] { byte1, byte2 };

//将产生的一个汉字的字节数组放入object数组中

bytes.SetValue(str_r, i);

}

return bytes;

}

private string stxt(int num)

{

Encoding gb = Encoding.GetEncoding("gb2312");

//调用函数产生10个随机中文汉字编码

object[] bytes = CreateRegionCode(num);

string strtxt = "";

//根据汉字编码的字节数组解码出中文汉字

for (int i = 0; i < num; i++)

{

strtxt += gb.GetString((byte[])Convert.ChangeType(bytes[i], typeof(byte[])));

}

return strtxt;

}

/// <summary>

/// 这个是使用字母,数字混合

/// </summary>

/// <param name="VcodeNum"></param>

/// <returns></returns>

private string CreateRandomCode(int codeCount)

{

string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";

string[] allCharArray = allChar.Split(\',\');

string randomCode = "";

int temp = -1;

Random rand = new Random();

for (int i = 0; i < codeCount; i++)

{

if (temp != -1)

{

rand = new Random(i * temp * ((int)DateTime.Now.Ticks));

}

int t = rand.Next(61);

if (temp == t)

{

return CreateRandomCode(codeCount);

}

temp = t;

randomCode += allCharArray[t];

}

return randomCode;

}

private void CreateImage(string checkCode)

{

int iwidth = (int)(checkCode.Length * 20);

System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 25);

Graphics g = Graphics.FromImage(image);

Font f = new System.Drawing.Font("Arial", 10, System.Drawing.FontStyle.Bold);

Brush b = new System.Drawing.SolidBrush(Color.White);

//g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);

g.Clear(Color.Black);

g.DrawString(checkCode, f, b, 3, 3);

Pen blackPen = new Pen(Color.Black, 0);

Random rand = new Random();

//for (int i=0;i<5;i++)

//{

// int y = rand.Next(image.Height);

// g.DrawLine(blackPen,0,y,image.W

idth,y);

//}

System.IO.MemoryStream ms = new System.IO.MemoryStream();

image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);

Response.ClearContent();

Response.ContentType = "image/Jpeg";

Response.BinaryWrite(ms.ToArray());

g.Dispose();

image.Dispose();

}

　　(实例2):20101018续加

调用页面前台代码

function Regist()

{

var url = "";

url = "/GZPI/Service/Registry/ViewProtocol.aspx";

window.open(url);

return false;

}

function LoginClick()

{

if(document.Login.UserName.value == "")

{

alert("用户名不能为空！");

return false;

}

document.Login.submit();

document.Login.Password.value = "";

return false;

}

function f_refreshtype()

{

var Image1 = document.getElementById("IMGCheckCode");

if (Image1 != null)

{

Image1.src = Image1.src + "?";

}

</script>

<TR>

<TD vAlign="bottom" align="left" width="62%"><input id="Text1" style="BORDER-RIGHT: #43a7e2 1px solid; BORDER-TOP: #43a7e2 1px solid; BACKGROUND: #fcfcfc; BORDER-LEFT: #43a7e2 1px solid; BORDER-BOTTOM: #43a7e2 1px solid"

size="13" name="UserName" width="100px">

</TD>

</TR>

<TR>

<TD vAlign="bottom" align="left" height="23"><input id="Password1" style="BORDER-RIGHT: #43a7e2 1px solid; BORDER-TOP: #43a7e2 1px solid; BACKGROUND: #fcfcfc; BORDER-LEFT: #43a7e2 1px solid; BORDER-BOTTOM: #43a7e2 1px solid"

type="password" size="13" name="Password" width="100px">

</TD>

</TR>

<TR>

<TD valign="top" align="left" height="23"><FONT face="宋体"><INPUT id="CheckCode" style="BORDER-RIGHT: #43a7e2 1px solid; BORDER-TOP: #43a7e2 1px solid; BACKGROUND: #fcfcfc; BORDER-LEFT: #43a7e2 1px solid; BORDER-BOTTOM: #43a7e2 1px solid"

width="100px" size="13" name="CheckCode"> </FONT><a style="CURSOR: hand" onclick="f_refreshtype()" title="看不清楚?点击获取新的校验码!" border="0"><IMG id="IMGCheckCode" src="../GenerateCheckCode.aspx"></a>

</TD>

</TR>

<TD class="dlbuttom" colSpan="2" height="23"><input id="Image1" style="CURSOR: hand" onclick="return LoginClick();" tabIndex="3" type="image"

height="17" width="55" src="images/login.gif" border="0" name="OkButton">   

<input type="image" onClick="return Regist();" border=\'0\' src=\'images/zuce.gif\' width=\'55\'

height=\'17\' ID="Image2" NAME="Image2">

</TD>

</TR>

</TABLE>

调用页面后台代码

private void OK_Click(object sender, System.EventArgs e)

{

if (!CheckCodeSame(CheckCode.Text.Trim()))

{

System.Web.HttpContext.Current.Response.Write("<Script Language=\'JavaScript\'>window.alert(\'校验码错误！请重新输入！\');window.close();</script>");

return;

}

int userType = 1;

try

{

userType = int.Parse(UserType.Text);

}

catch

{

}

GatewayManager gateway = new GatewayManager(corpCode.Text,collegeCode.Text,chargeCode.Text,userName.Text,password.Text,userType);

gateway.Login(this);

}

/// <summary>

/// 判断输入的校验码是否正确

/// </summary>

/// <param name="checkCode"></param>

/// <returns></returns>

public static bool CheckCodeSame(string checkCode)

{

bool bSame = false; ;

if (HttpContext.Current.Session["CheckCode"] != null)

{

if (checkCode.ToUpper() == HttpContext.Current.Session["CheckCode"].ToString().ToUpper())

{

bSame = true;

}

return bSame;

}

生成验证码前台文件

<HTML>

<HEAD>

<title>GenerateCheckCode</title>

</HEAD>

<body>

</div>

</form>

</body>

</HTML>

生成验证码后台文件

using System;

using System.Collections;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Drawing;

using System.Drawing.Drawing2D;

namespace GZPI.Gateway

{

/// <summary>

/// GenerateCheckCode 的摘要说明。

/// </summary>

public class GenerateCheckCode : System.Web.UI.Page

{

private void Page_Load(object sender, System.EventArgs e)

{

// 在此处放置用户代码以初始化页面

this.CreateCheckCodeImage(GenerateCheckCodes(4));

}

#region Web 窗体设计器生成的代码

override protected void OnInit(EventArgs e)

{

// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。

InitializeComponent();

base.OnInit(e);

}

/// <summary>

/// 设计器支持所需的方法 - 不要使用代码编辑器修改

/// 此方法的内容。

/// </summary>

private void InitializeComponent()

{

this.Load += new System.EventHandler(this.Page_Load);

}

#endregion

private string GenerateCheckCodes(int iCount)

{

int number;

string checkCode = String.Empty;

int iSeed = DateTime.Now.Millisecond;

System.Random random = new Random(iSeed);

for (int i = 0; i < iCount; i++)

{

number = random.Next(10);

checkCode += number.ToString();

}

Session["CheckCode"] = checkCode;

return checkCode;

}

private void CreateCheckCodeImage(string checkCode)

{

if (checkCode == null || checkCode.Trim() == String.Empty)

return;

int iWordWidth = 15;

int iImageWidth = checkCode.Length * iWordWidth;

Bitmap image = new Bitmap(iImageWidth, 20);

Graphics g = Graphics.FromImage(image);

try

{

//生成随机生成器

Random random = new Random();

//清空图片背景色

g.Clear(Color.White);

//画图片的背景噪音点

for (int i = 0; i < 20; i++)

{

int x1 = random.Next(image.Width);

int x2 = random.Next(image.Width);

int y1 = random.Next(image.Height);

int y2 = random.Next(image.Height);

g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);

}

//画图片的背景噪音线

for (int i = 0; i < 2; i++)

{

int x1 = 0;

int x2 = image.Width;

int y1 = random.Next(image.Height);

int y2 = random.Next(image.Height);

if (i == 0)

{

g.DrawLine(new Pen(Color.Gray, 2), x1, y1, x2, y2);

}

for (int i = 0; i < checkCode.Length; i++)

{

string Code = checkCode[i].ToString();

int xLeft = iWordWidth * (i);

random = new Random(xLeft);

int iSeed = DateTime.Now.Millisecond;

int iValue = random.Next(iSeed) % 4;

if (iValue == 0)

{

Font font = new Font("Arial", 13, (FontStyle.Bold | System.Drawing.FontStyle.Italic));

Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);

LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Blue, Color.Red, 1.5f, true);

g.DrawString(Code, font, brush, xLeft, 2);

}

else if (iValue == 1)

{

Font font = new System.Drawing.Font("楷体", 13, (FontStyle.Bold));

Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);

LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Blue, Color.DarkRed, 1.3f, true);

g.DrawString(Code, font, brush, xLeft, 2);

}

else if (iValue == 2)

{

Font font = new System.Drawing.Font("宋体", 13, (System.Drawing.FontStyle.Bold));

Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);

LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Green, Color.Blue, 1.2f, true);

g.DrawString(Code, font, brush, xLeft, 2);

}

else if (iValue == 3)

{

Font font = new System.Drawing.Font("黑体", 13, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Bold));

Rectangle rc = new Rectangle(xLeft, 0, iWordWidth, image.Height);

LinearGradientBrush brush = new LinearGradientBrush(rc, Color.Blue, Color.Green, 1.8f, true);

g.DrawString(Code, font, brush, xLeft, 2);

}

//////画图片的前景噪音点

//for (int i = 0; i < 8; i++)

//{

// int x = random.Next(image.Width);

// int y = random.Next(image.Height);

// image.SetPixel(x, y, Color.FromArgb(random.Next()));

//}

//画图片的边框线

g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

System.IO.MemoryStream ms = new System.IO.MemoryStream();

image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);

Response.ClearContent();

Response.BinaryWrite(ms.ToArray());

}

finally

{

g.Dispose();

image.Dispose();

}

　　四、效果图展示

　　验证码数字

.net实现验证码功能 - 飛雪飄寒

　　验证码数字+字母

　　验证码汉字