完成接口，生成器，配置等

Falcon.ValidateCode/IValidateCode.cs

@@ -1,6 +1,4 @@
-using System;
+using System.IO;
-using System.Collections.Generic;
-using System.Text;
 
 namespace Falcon.ValidateCode
 {
@@ -9,6 +7,17 @@ namespace Falcon.ValidateCode
     /// </summary>
     public interface IValidateCode
     {
+        /// <summary>
+        /// 生成随机代码
+        /// </summary>
+        /// <returns></returns>
+        string GenerateCode();
 
+        /// <summary>
+        /// 根据代码生成验证图片
+        /// </summary>
+        /// <param name="code"></param>
+        /// <returns></returns>
+        Stream GenerateImgStream(string code);
     }
 }

Falcon.ValidateCode/ValidateCode.cs

@@ -0,0 +1,95 @@
+using System;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.IO;
+using System.Text;
+
+namespace Falcon.ValidateCode
+{
+    /// <summary>
+    /// 图片验证码
+    /// </summary>
+    public class VerificationCodeServices:IValidateCode
+    {
+        /// <summary>
+        /// 生成选项
+        /// </summary>
+        public ValidateCodeOption Options { get; set; }
+        private static Random _ran = new Random(unchecked((int)DateTime.Now.Ticks));
+        /// <summary>
+        /// 实例化验证码生成器
+        /// </summary>
+        public VerificationCodeServices() : this(new ValidateCodeOption()) {
+
+        }
+        /// <summary>
+        /// 通过提供配置实例化验证码生成器
+        /// </summary>
+        /// <param name="option"></param>
+        public VerificationCodeServices(ValidateCodeOption option) {
+            this.Options = option;
+        }
+        /// <summary>
+        /// 生成随机验证码
+        /// </summary>
+        public string GenerateCode() {
+            var charLen = this.Options.CodeChars.Length;
+            StringBuilder code = new StringBuilder(charLen);
+            for(int i = 0;i < this.Options.CodeLength;i++) {
+                var nextC = _ran.Next(charLen);
+                var c = this.Options.CodeChars.Substring(nextC,1);
+                code.Append(c);
+            }
+            return code.ToString();
+        }
+        /// <summary>
+        /// 生成图片数据流
+        /// </summary>
+        /// <param name="code"></param>
+        /// <returns></returns>
+        public Stream GenerateImgStream(string code) {
+            if(string.IsNullOrEmpty(code)) {
+                throw new ArgumentNullException(nameof(code));
+            }
+            Bitmap Img = null;
+            Graphics graphics = null;
+            MemoryStream ms = null;
+            Random random = new Random();
+            //颜色集合  
+            Color[] color = { Color.Black,Color.Red,Color.DarkBlue,Color.Green,Color.Orange,Color.Brown,Color.DarkCyan,Color.Purple };
+            //字体集合
+            string[] fonts = { "Verdana","Microsoft Sans Serif","Comic Sans MS","Arial","宋体" };
+            //定义图像的大小，生成图像的实例  
+            Img = new Bitmap((int)code.Length * 18,32);
+            graphics = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象    
+            graphics.Clear(Color.White);//背景设为白色  
+
+            //在随机位置画背景点  
+
+            for(int i = 0;i < 100;i++) {
+                int x = random.Next(Img.Width);
+                int y = random.Next(Img.Height);
+                graphics.DrawRectangle(new Pen(Color.LightGray,0),x,y,1,1);
+            }
+
+            //验证码绘制在graphics中  
+            for(int i = 0;i < code.Length;i++) {
+                int colorIndex = random.Next(7);//随机颜色索引值  
+                int fontIndex = random.Next(4);//随机字体索引值  
+                Font font = new Font(fonts[fontIndex],15,FontStyle.Bold);//字体  
+                Brush brush = new SolidBrush(color[colorIndex]);//颜色  
+                int y = 4;
+                if((i + 1) % 2 == 0)//控制验证码不在同一高度  
+                {
+                    y = 2;
+                }
+                graphics.DrawString(code.Substring(i,1),font,brush,3 + (i * 12),y);//绘制一个验证字符  
+            }
+            ms = new MemoryStream();//生成内存流对象  
+            Img.Save(ms,ImageFormat.Png);//将此图像以Png图像文件的格式保存到流中  
+            graphics.Dispose();
+            Img.Dispose();
+            return ms;
+        }
+    }
+}

Falcon.ValidateCode/ValidateCodeOption.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Falcon.ValidateCode
+{
+    /// <summary>
+    /// 生成验证码选项
+    /// </summary>
+    public class ValidateCodeOption
+    {
+        /// <summary>
+        /// 验证码使用的字符
+        /// </summary>
+        public string CodeChars { get; set; } = "0123456789ABCDEFGHIJKLMNPQRSTUVWXYZ";
+        /// <summary>
+        /// 生成验证码的长度
+        /// </summary>
+        public int CodeLength { get; set; } = 5;
+    }
+}