GDI画验证码

 Random r = new Random();
            string str = "";
            for (int i = 0; i < 5; i++)
            {
               int a= r.Next(0, 10);
               str += a;//将数字连接到一块
            }

            Bitmap bm = new Bitmap(150, 90);//创建位图对象
            Graphics g = Graphics.FromImage(bm);//在bm中重新画图

            //创建字体跟颜色数组
            string[] font = { "楷体", "黑体", "宋体", "斜体", "新宋体" };
            Color[] colors = { Color.Red, Color.Blue, Color.Green, Color.Yellow, Color.YellowGreen };

            //开始画图

            for (int i = 0; i < 5; i++)
            {
                Point p=new Point (i*20,0);
                g.DrawString(str[i].ToString(), new Font(font[i], 20, FontStyle.Bold), new SolidBrush(colors[i]), p);
            }
            pictureBox1.Image = bm;//将位图显示到picture上