C# 生成簡單驗證碼的代碼

pb44 9年前發布 | 3K 次閱讀 C#

C#生成簡單驗證碼的代碼

html頁面

<!--
    Document   : ASP.NET用一般處理程序生成驗證碼
    Created on : 2008-10-13 17：04
    Author     : 牛腩
-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title></title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <script type="text/javascript">
        function change() {
            var imgNode = document.getElementById("vimg");
            imgNode.src = "WaterMark.ashx?t=" + (new Date()).valueOf();  // 這里加個時間的參數是為了防止瀏覽器緩存的問題
        }
    </script>
  </head>
  <body>
    <img src="WaterMark.ashx" id="vimg" alt="" /><input type="button" value="換一張圖片" onclick="change()" />
  </body>
</html>

C#代碼

//一般處理程序WaterMark.ashx的代碼
<%@ WebHandler Language="C#" Class="WaterMark" %>


using System;
using System.Web;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Web.SessionState;


public class WaterMark : IHttpHandler, IRequiresSessionState  // 要使用session必須實現該接口,記得要導入System.Web.SessionState命名空間
{



public void ProcessRequest(HttpContext context)
{
    string checkCode = GenCode(5);  // 產生5位隨機字符
    context.Session["Code"] = checkCode; //將字符串保存到Session中，以便需要時進行驗證
    System.Drawing.Bitmap image = new System.Drawing.Bitmap(70, 22);
    Graphics g = Graphics.FromImage(image);
    try
    {
        //生成隨機生成器
        Random random = new Random();

        //清空圖片背景色
        g.Clear(Color.White);

        // 畫圖片的背景噪音線
        int i;
        for (i = 0; i < 25; 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);
        }

        Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));
        System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, true);
        g.DrawString(checkCode, font, brush, 2, 2);

        //畫圖片的前景噪音點
        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);
        context.Response.ClearContent();
        context.Response.ContentType = "image/Gif";
        context.Response.BinaryWrite(ms.ToArray());
    }
    finally
    {
        g.Dispose();
        image.Dispose();
    }
}

/// <summary>
/// 產生隨機字符串
/// </summary>
/// <param name="num">隨機出幾個字符</param>
/// <returns>隨機出的字符串</returns>
private string GenCode(int num)
{
    string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    char[] chastr = str.ToCharArray();
    // string[] source ={ "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", "V", "W", "X", "Y", "Z", "#", "$", "%", "&", "@" };
    string code = "";
    Random rd = new Random();
    int i;
    for (i = 0; i < num; i++)
    {
        //code += source[rd.Next(0, source.Length)];
        code += str.Substring(rd.Next(0, str.Length), 1);
    }
    return code;

}

public bool IsReusable
{
    get
    {
        return false;
    }
}




}</pre>
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