开发基于Web Service的图片验证码服务

最近一直在研究SmartClient ，因工作需要，参考了网友的代码后，写了这个基于Web Service的图片验证码服务 ，和大家共同分享。


具体实现如下：
在VS2003.NET中新建web服务，名称为SmartClientWS，添加代码如下：
　 本帖相关代码

/// <summary>
/// 生成图片验证码
/// </summary>
/// <param name="nLen">验证码的长度</param>
/// <param name="strKey">输出参数，验证码的内容</param>
/// <returns>图片字节流</returns>
[WebMethod]
public byte[] GenerateVerifyImage(int nLen,ref string strKey)
{
int nBmpWidth = 13*nLen+5;
int nBmpHeight = 25;
System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(nBmpWidth,nBmpHeight);

// 1. 生成随机背景颜色
int nRed,nGreen,nBlue; // 背景的三元色
System.Random rd = new Random((int)System.DateTime.Now.Ticks);
nRed = rd.Next(255)%128+128;
nGreen = rd.Next(255)%128+128;
nBlue = rd.Next(255)%128+128;

// 2. 填充位图背景
System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(bmp);
graph.FillRectangle(new SolidBrush(System.Drawing.Color.FromArgb(nRed,nGreen,nBlue))
,0
,0
,nBmpWidth
,nBmpHeight);


// 3. 绘制干扰线条，采用比背景略深一些的颜色
int nLines = 3;
System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.FromArgb(nRed-17,nGreen-17,nBlue-17),2);
for(int a =0;a< nLines;a++)
{
int x1 = rd.Next() % nBmpWidth;
int y1 = rd.Next() % nBmpHeight;
int x2 = rd.Next() % nBmpWidth;
int y2 = rd.Next() % nBmpHeight;
graph.DrawLine(pen,x1,y1,x2,y2);
}

// 采用的字符集，可以随即拓展，并可以控制字符出现的几率
string strCode = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

// 4. 循环取得字符，并绘制
string strResult = "";
for(int i=0;i<nLen;i++)
{
int x = (i*13 + rd.Next(3));
int y = rd.Next(4) + 1;

// 确定字体
System.Drawing.Font font = new System.Drawing.Font("Courier New",
12 + rd.Next()%4,
System.Drawing.FontStyle.Bold);
char c = strCode[rd.Next(strCode.Length)]; // 随机获取字符
strResult += c.ToString();

// 绘制字符
graph.DrawString(c.ToString(),
font,
new SolidBrush(System.Drawing.Color.FromArgb(nRed-60+y*3,nGreen-60+y*3,nBlue-40+y*3)),
x,
y);
}

// 5. 输出字节流
System.IO.MemoryStream bstream = new System.IO.MemoryStream();
bmp.Save(bstream,System.Drawing.Imaging.ImageFormat.Jpeg);
bmp.Dispose();
graph.Dispose();

strKey = strResult;
byte[] byteReturn = bstream.ToArray();
bstream.Close();

return byteReturn;
}

调用Web服务：
　 本帖相关代码

private void ShowImage()
{
GenerateImage.SmartClientService genrate=new officeSystem.ImageGenerate.GenerateImage.SmartClientService();

string strKey="";
s=genrate.GenerateVerifyImage(5,ref strKey);

if (s.Length > 0)
{
MemoryStream stream = new MemoryStream(s, true);

stream.Write(s, 0, s.Length);

DrawToScale(new Bitmap(stream));

stream.Close();
}

this.textBox3.Text=strKey.ToString();

}

以上代码，归属www.smartclient.com.cm