C# 验证码的简单生成，登录实现校验验证码

登录实现校验验证码

1、思路：首先写一个生成验证码的接口，接口传出就是验证码的唯一id和验证码图片的base64， 把验证码的id当做缓存的key，再把生成的验证码code当做值存到缓存中。

2、登录：输入用户名、密码、验证码唯一id和用户输入的验证码值。用验证码唯一id获取到缓存中的验证码值，再和用户输入的值相比较。。就简单实现了

3、验证码生成代码

 1  public class VerifyCodeHelper
 2  {
 3      public static string BuildCode(out string code)
 4      {
 5          code = string.Empty;
 6          Random rand = new Random();
 7          Bitmap bitmap = new Bitmap(85, 30);//设置宽高
 8          Graphics graphics = Graphics.FromImage(bitmap);//生成画布
 9          graphics.Clear(Color.White);//清空画布
10 
11          string letters = "023456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ";//去除 1 I l 
12          Random random = new Random();
13          //生成四位验证码
14          for (int i = 0; i < 4; i++)
15          {
16              code += letters[random.Next(0, letters.Length)];
17          }
18 
19          //画5条干扰线
20          for (int i = 0; i < 5; i++)
21          {
22              int x1 = random.Next(bitmap.Width);
23              int y1 = random.Next(bitmap.Height);
24              int x2 = random.Next(bitmap.Width);
25              int y2 = random.Next(bitmap.Height);
26              graphics.DrawLine(new Pen(Color.Coral), x1, y1, x2, y2);
27          }
28          //画150个干扰点
29          for (int i = 0; i < 150; i++)
30          {
31              int x1 = random.Next(bitmap.Width);
32              int y1 = random.Next(bitmap.Height);
33              bitmap.SetPixel(x1, y1, Color.FromArgb(random.Next()));//随机颜色填充
34          }
35          //画个边框
36          graphics.DrawRectangle(new Pen(Color.Black), new Rectangle(0, 0, bitmap.Width - 1, bitmap.Height - 1));
37 
38          int randAngle = 45;//随机转动角度 //验证码旋转，防止机器识别
39          char[] chars = code.ToCharArray();//拆散字符串成单字符数组
40          //文字居中
41          StringFormat format = new StringFormat(StringFormatFlags.NoClip);
42          format.Alignment = StringAlignment.Center;
43          format.LineAlignment = StringAlignment.Center;
44          //定义颜色
45          Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
46          //定义字体
47          string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
48          for (int i = 0; i < chars.Length; i++)
49          {
50              int cindex = rand.Next(7);
51              int findex = rand.Next(5);
52              //字体样式(参数2为字体大小)
53              Font f = new System.Drawing.Font(font[findex], 13, System.Drawing.FontStyle.Bold);
54              Brush b = new System.Drawing.SolidBrush(c[cindex]);
55              Point dot = new Point(16, 16);
56 
57              float angle = rand.Next(-randAngle, randAngle);//转动的度数
58              graphics.TranslateTransform(dot.X, dot.Y);//移动光标到指定位置
59              graphics.RotateTransform(angle);
60              graphics.DrawString(chars[i].ToString(), f, b, 1, 1, format);
61 
62              graphics.RotateTransform(-angle);//转回去
63              graphics.TranslateTransform(2, -dot.Y);//移动光标到指定位置
64          }
65          string strbaser64 = string.Empty;
66          using (System.IO.MemoryStream stream = new System.IO.MemoryStream())
67          {
68              bitmap.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);
69              byte[] arr = new byte[stream.Length];
70              stream.Position = 0;
71              stream.Read(arr, 0, (int)stream.Length);
72              strbaser64 = Convert.ToBase64String(arr);
73          }
74          return strbaser64;
75      }
76  }