C#登录界面验证码

登录界面验证码

效果

图中从左到右工具名称：label、textBox、PictureBox

代码

1.新建C#脚本：“ValidCode”（这一段我是在网上找的代码）：

class ValidCode
{
#region Private Fields
private const double PI = 3.1415926535897932384626433832795;
private const double PI2 = 6.283185307179586476925286766559;
//private readonly int _wordsLen = 4;
private int _len;
private CodeType _codetype;
private readonly Single _jianju = (float)18.0;
private readonly Single _height = (float)24.0;
private string _checkCode;
#endregion
#region Public Property
public string CheckCode
{
get
{
return _checkCode;
}
}
#endregion
#region Constructors
public ValidCode(int len, CodeType ctype)
{

this._len = len;

this._codetype = ctype;

}

#endregion

#region Public Field

public enum CodeType { Words, Numbers, Characters, Alphas }

#endregion

#region Private Methods

private string GenerateNumbers()
{

string strOut = "";

System.Random random = new Random();

for (int i = 0; i < _len; i++)
{

string num = Convert.ToString(random.Next(10000) % 10);

strOut += num;

}

return strOut.Trim();

}

private string GenerateCharacters()
{

string strOut = "";

System.Random random = new Random();

for (int i = 0; i < _len; i++)
{

string num = Convert.ToString((char)(65 + random.Next(10000) % 26));

strOut += num;

}

return strOut.Trim();

}

//

private string GenerateAlphas()
{

string strOut = "";

string num = "";

System.Random random = new Random();

for (int i = 0; i < _len; i++)
{

if (random.Next(500) % 2 == 0)
{

num = Convert.ToString(random.Next(10000) % 10);

}

else
{

num = Convert.ToString((char)(65 + random.Next(10000) % 26));

}

strOut += num;

}

return strOut.Trim();

}

private System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
{

System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);

// 将位图背景填充为白色

System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);

graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);

graph.Dispose();

double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;

for (int i = 0; i < destBmp.Width; i++)
{

for (int j = 0; j < destBmp.Height; j++)
{

double dx = 0;

dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;

dx += dPhase;

double dy = Math.Sin(dx);

// 取得当前点的颜色

int nOldX = 0, nOldY = 0;

nOldX = bXDir ? i + (int)(dy * dMultValue) : i;

nOldY = bXDir ? j : j + (int)(dy * dMultValue);

System.Drawing.Color color = srcBmp.GetPixel(i, j);

if (nOldX >= 0 && nOldX < destBmp.Width

&& nOldY >= 0 && nOldY < destBmp.Height)
{

destBmp.SetPixel(nOldX, nOldY, color);

}

}

}

return destBmp;

}

#endregion

#region Public Methods

public Stream CreateCheckCodeImage()
{

string checkCode;

switch (_codetype)
{

case CodeType.Alphas:

checkCode = GenerateAlphas();

break;

case CodeType.Numbers:

checkCode = GenerateNumbers();

break;

case CodeType.Characters:

checkCode = GenerateCharacters();

break;

default:

checkCode = GenerateAlphas();

break;

}

this._checkCode = checkCode;

MemoryStream ms = null;

//

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

return null;

Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * _jianju)), (int)_height);

Graphics g = Graphics.FromImage(image);

try
{

Random random = new Random();

g.Clear(Color.White);

// 画图片的背景噪音线

for (int i = 0; i < 18; 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.FromArgb(random.Next()), 1), x1, y1, x2, y2);

}

Font font = new System.Drawing.Font("Times New Roman", 14, System.Drawing.FontStyle.Bold);

LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

if (_codetype != CodeType.Words)
{

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

g.DrawString(checkCode.Substring(i, 1), font, brush, 2 + i * _jianju, 1);

}

}
else
{

g.DrawString(checkCode, font, brush, 2, 2);

}

// 画图片的前景噪音点

for (int i = 0; i < 150; i++)
{

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

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

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

}

// 画图片的波形滤镜效果

if (_codetype != CodeType.Words)
{

image = TwistImage(image, true, 3, 1);

}

// 画图片的边框线

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

ms = new System.IO.MemoryStream();

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

}

finally
{

g.Dispose();

image.Dispose();

}

return ms;

}

#endregion

}

2.在登录界面中编辑代码：
①实例化对象：

ValidCode validCode = new ValidCode(5, ValidCode.CodeType.Numbers);

②在登录按钮点击事件中编辑，如果验证码输入错误会提示：

if (!this.txtValidCode.Text.Equals(validCode.CheckCode))
{
MessageBox.Show("请输入正确的验证码！", "提示");
this.txtValidCode.Focus();
this.txtValidCode.Text = "";
return;
}

③在登录界面加载事件、PictureBox的点击事件、密码错误事件、用户名不存在事件、登录成功事件中插入代码（验证码图片更换）：

picValidCode.Image = Bitmap.FromStream(validCode.CreateCheckCodeImage());

④在登录成功事件中插入代码（textBox清空）：

textBox.Clear();

3.完成。