如何实现验证码的功能?

发布网友 发布时间：2022-04-21 14:56

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热心网友 时间：2022-05-18 14:03

两个页面，一个验证码方法的页面，一个是调用的页面。

页面一：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;

public partial class PicValidateCode : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
//4位数字的验证码
string str_ValidateCode = GetRandomNumberString(4);
//用于验证的Session
Session["ValidateCode"] = str_ValidateCode;
CreateImage(str_ValidateCode);
}

}

//生成随机数字字符串
public string GetRandomNumberString(int int_NumberLength)
{
string str_Number = string.Empty;
Random theRandomNumber = new Random();

for (int int_index = 0; int_index < int_NumberLength; int_index++)
{
str_Number += theRandomNumber.Next(10).ToString();
}
return str_Number;
}

public Color GetRandomColor()
{
Random RandomNum_First = new Random((int)DateTime.Now.Ticks);
//随机数
System.Threading.Thread.Sleep(RandomNum_First.Next(50));
Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks);

//为了在白色背景上显示，尽量生成深色
int int_Red = RandomNum_First.Next(256);
int int_Green = RandomNum_Sencond.Next(256);
int int_Blue = (int_Red + int_Green > 400) ? 0 : 400 - int_Red - int_Green;
int_Blue = (int_Blue > 255) ? 255 : int_Blue;

return Color.FromArgb(int_Red, int_Green, int_Blue);
}

public void CreateImage(string str_ValidateCode)
{
int int_ImageWidth = str_ValidateCode.Length * 13;
Random newRandom = new Random();
//图高20px
Bitmap theBitmap = new Bitmap(int_ImageWidth, 20);
Graphics theGraphics = Graphics.FromImage(theBitmap);
//白色背景
theGraphics.Clear(Color.White);
// 灰色边框
theGraphics.DrawRectangle(new Pen(Color.LightGray, 1), 0, 0, int_ImageWidth - 1, 19);

//10pt的字体
Font theFont = new Font("Arial", 10);

for (int int_index = 0; int_index < str_ValidateCode.Length; int_index++)
{
string str_char = str_ValidateCode.Substring(int_index, 1);
Brush newBrush = new SolidBrush(GetRandomColor());
Point thePos = new Point(int_index * 13 + 1 + newRandom.Next(3), 1 + newRandom.Next(3));
theGraphics.DrawString(str_char, theFont, newBrush, thePos);
}

//将生成的图片发回客户端
MemoryStream ms = new MemoryStream();
theBitmap.Save(ms, ImageFormat.Png);
//需要输出图象信息
Response.ClearContent();
Response.ContentType = "image/Png";
Response.BinaryWrite(ms.ToArray());
theGraphics.Dispose();
theBitmap.Dispose();
Response.End();
}
}

页面二：
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void Button1_Click(object sender, EventArgs e)
{
if (this.TextBox1.Text.Equals(Session["ValidateCode"]))
{
Response.Write("<script language=javascript>alert('有效');</script>");
}
else
{
Response.Write("<script language=javascript>alert('无效');</script>");
}
}
}