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图片登陆验证功能的实现

2013-05-02 15:02 766 查看

首先HTML端代码：

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>教师教学经验共享平台</title>
<link href="css/css.css" rel="stylesheet" type="text/css" />
<script language="javascript" type="text/javascript">
function ChangeCode() {

var date = new Date();
var myImg = document.getElementById("ImageCheck");
var GUID = document.getElementById("lblGUID");

if (GUID != null) {
if (GUID.innerHTML != "" && GUID.innerHTML != null) {
myImg.src = "admin/VdCode.aspx?GUID=" + GUID.innerHTML + "&flag=" + date.getMilliseconds()

}
}
return false;
}
</script>
</head>
<body>
<form runat="server" id="from1">
<div class="zhong">
<ucl:head1 runat="server" ID="top" />
<div class="main">
<div style="border: 1px solid #ccc; height: 300px;">
<div style="background: url(images/bg_12.png); text-align: left; height: 30px; line-height: 30px">
用户登录</div>
<table width="50%" border="0" cellspacing="5" align="left" cellpadding="0">
<tr>
<td>
</td>
</tr>
<tr>
<td width="32%" height="37" align="right" valign="middle">
登录账号：
</td>
<td width="68%" valign="middle" align="left">
<input type="text" name="textfield" id="txtName" style="width: 200px" runat="server" />
</td>
</tr>
<tr>
<td height="37" valign="middle" align="right">
登录密码：
</td>
<td valign="middle" align="left">
<input type="password" name="textfield2" id="txtPwd" style="width: 200px" runat="server" />
</td>
</tr>
<tr>
<td height="37" valign="middle" align="right">
验 证 码：<asp:Label ID="lblGUID" runat="server" Style="display: none"></asp:Label>
</td>
<td valign="middle" align="left">
<input type="text" name="textfield3" id="CheckCode" runat="server" style="float: left" />
<a id="A2" href="" onclick="ChangeCode();return false;">
<asp:Image ID="ImageCheck" runat="server" ImageUrl="admin/VdCode.aspx?GUID=GUID"
ImageAlign="AbsMiddle" ToolTip="看不清，换一个"></asp:Image>
</a>
</td>
</tr>
<tr>
<td align="right">
</td>
<td align="left">
<asp:ImageButton ImageUrl="images/login.png" runat="server" ID="ibLogin" OnClick="ibLogin_Click" />
</td>
</tr>
</table>
<table width="50%" border="0" cellspacing="5" align="right" cellpadding="0">
<tr>
<td style="height: 200px; width: 1px; background: #ccc;">
</td>
<td align="center">
现在还没有账号<a href="reg.aspx">立即注册</a>
</td>
</tr>
</table>
</div>
</div>
<div class="bottom">
教师教学经验共享平台
</div>
</div>
</form>
</body>
</html>

后台代码实现：

public partial class VdCode : System.Web.UI.Page
{
private void Page_Load(object sender, System.EventArgs e)
{
string checkCode = GetRandomCode(4);
Session["CheckCode"] = checkCode;
SetPageNoCache();
CreateImage(checkCode);
}

/// <summary>
/// 设置页面不被缓存
/// </summary>
private void SetPageNoCache()
{
Response.Buffer = true;
Response.ExpiresAbsolute = System.DateTime.Now.AddSeconds(-1);
Response.Expires = 0;
Response.CacheControl = "no-cache";
Response.AppendHeader("Pragma", "No-Cache");
}

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,M,N,P,Q,R,S,T,U,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(35);
if (temp == t)
{
return CreateRandomCode(codeCount);//性能问题
}
temp = t;
randomCode += allCharArray[t];
}
return randomCode;
}
private string GetRandomCode(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,M,N,P,Q,R,S,T,U,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(temp * i * ((int)DateTime.Now.Ticks));
}

int t = rand.Next(33);

while (temp == t)
{
t = rand.Next(33);
}

temp = t;
RandomCode += allCharArray[t];
}

return RandomCode;
}
private void CreateImage(string checkCode)
{
int iwidth = (int)(checkCode.Length * 14);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
Graphics g = Graphics.FromImage(image);
Font f = new System.Drawing.Font("Arial ", 10);//, System.Drawing.FontStyle.Bold);
Brush b = new System.Drawing.SolidBrush(Color.Black);
Brush r = new System.Drawing.SolidBrush(Color.FromArgb(166, 8, 8));

//g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);
//			g.Clear(Color.AliceBlue);//背景色
g.Clear(System.Drawing.ColorTranslator.FromHtml("#99C1CB"));//背景色

char[] ch = checkCode.ToCharArray();
for (int i = 0; i < ch.Length; i++)
{
if (ch[i] >= '0' && ch[i] <= '9')
{
//数字用红色显示
g.DrawString(ch[i].ToString(), f, r, 3 + (i * 12), 3);
}
else
{   //字母用黑色显示
g.DrawString(ch[i].ToString(), f, b, 3 + (i * 12), 3);
}
}

//for循环用来生成一些随机的水平线
//			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.Width,y);
//			}

System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
//history back 不重复
Response.Cache.SetNoStore();//这一句
Response.ClearContent();
Response.ContentType = "image/Jpeg";
Response.BinaryWrite(ms.ToArray());
g.Dispose();
image.Dispose();
}
}
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