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现在大部分网站登陆时都会要求输入验证码，在网上也看了一些范例，现在总结一下如何实现无刷新页面生成验证码。 效果图：
实现方式： 前台： <div> <span>Identifying Code:</span> <asp:TextBox ID="txtValidationCode" runat="server" Width="130px" MaxLength="4"></asp:TextBox> <img id="imgYZ" class="code" style=" height:23px; width:65px;" src="Img.ashx" onclick="this.src=this.src+'?'"/ /> <img src="../images/btn_change.gif" title="Change" class="btn_change" Style="cursor: hand" onclick="ImgChange()" /> </div> JS：
<script language="javascript" type="text/javascript">
function ImgChange()
{
var img=document.getElementById("imgYZ");
img.click();
}
</script>
ashx:
using System;
using System.Web;
using CLAIMS.BLL;
using System.Data;
using System.Configuration;
using System.Web.SessionState;
using System.Drawing;
public class Img : IHttpHandler, IRequiresSessionState
{
public void ProcessRequest (HttpContext context)
{
context.Response.ContentType = "image/Jpeg";
string s_random = "";
System.IO.MemoryStream ms = new System.IO.MemoryStream();
s_random = RndNum(4);
context.Session["random"] = s_random;
s_random = s_random.Substring(0, 1) + " " + s_random.Substring(1, 1) + " " + s_random.Substring(2, 1) + " " + s_random.Substring(3, 1);
CreateImage(s_random, ref ms);
context.Response.ClearContent();
context.Response.BinaryWrite(ms.ToArray());
context.Response.Flush();
context.Response.End();
}
private void CreateImage(string checkCode,ref System.IO.MemoryStream ms)
{
int iwidth = (int)(checkCode.Length * 18);
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 45);
Graphics g = Graphics.FromImage(image);
g.Clear(Color.White);
//定义颜色
Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
//定义字体
//string[] font = {"Verdana","Microsoft Sans Serif","Comic Sans MS","Arial","宋体"};
Random rand = new Random();
//随机输出噪点
for (int i = 0; i < 50; i++)
{
int x = rand.Next(image.Width);
int y = rand.Next(image.Height);
g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
}
//输出不同字体和颜色的验证码字符
for (int i = 0; i < checkCode.Length; i++)
{
int cindex = rand.Next(7);
int findex = rand.Next(5);
Font font = new System.Drawing.Font("Arial", 24, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));
Brush b = new System.Drawing.SolidBrush(c[cindex]);
int ii = 4;
if ((i + 1) % 2 == 0)
{
ii = 2;
}
g.DrawString(checkCode.Substring(i, 1), font, b, 3 + (i * 12), ii);
}
//画一个边框
g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);
//输出到浏览器
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
g.Dispose();
image.Dispose();
}
public static String RndNum(int VcodeNum)
{
String Vchar = "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";
String[] VcArray = Vchar.Split(',');
String VNum = "";
Random random = new Random();
for (int i = 1; i <= VcodeNum; i++)
{
int iNum = 0;
while ((iNum = Convert.ToInt32(VcArray.Length * random.NextDouble())) == VcArray.Length)
{
iNum = Convert.ToInt32(VcArray.Length * random.NextDouble());
}
VNum += VcArray[iNum];
}
return VNum;
}
public bool IsReusable {
get {
return false;
}
}
}
备注： onclick="this.src=this.src+'?'" 之前一直不明白为什么要加一个？号，于是去网上搜索，参考一下前辈们的见解： 【这是表示当前图片链接，在当前链接值的基础上添加了一个问号 【GET：当客户端要从服务器中读取文档时，使用GET方法。GET方法要求服务器将URL定位的资源放在响应报文的数据部分，回送给客户端。使用GET方法时，请求参数和对应的值附加在URL后面，利用一个问号（“?”）代表URL的结尾与请求参数的开始，传递参数长度受限制。例如，/index.jsp?id=100&op=bind。 以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持极客世界。 |
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