.NET Core 2.0如何生成图片验证码完整实例

using System;
using System.DrawingCore;
using System.DrawingCore.Drawing2D;
using System.DrawingCore.Imaging;
using System.IO;
 
namespace Common.Helper
{
 public sealed class VerifyCodeHelper
 {
  #region 单例模式
  //创建私有化静态obj锁 
  private static readonly object _ObjLock = new object();
  //创建私有静态字段，接收类的实例化对象 
  private static VerifyCodeHelper _VerifyCodeHelper = null;
  //构造函数私有化 
  private VerifyCodeHelper() { }
  //创建单利对象资源并返回 
  public static VerifyCodeHelper GetSingleObj()
  {
   if (_VerifyCodeHelper == null)
   {
    lock (_ObjLock)
    {
     if (_VerifyCodeHelper == null)
      _VerifyCodeHelper = new VerifyCodeHelper();
    }
   }
   return _VerifyCodeHelper;
  }
  #endregion
 
  #region 生产验证码
  public enum VerifyCodeType { NumberVerifyCode, AbcVerifyCode, MixVerifyCode };
 
  /// <summary>
  /// 1.数字验证码
  /// </summary>
  /// <param name="length"></param>
  /// <returns></returns>
  private string CreateNumberVerifyCode(int length)
  {
   int[] randMembers = new int[length];
   int[] validateNums = new int[length];
   string validateNumberStr = "";
   //生成起始序列值 
   int seekSeek = unchecked((int)DateTime.Now.Ticks);
   Random seekRand = new Random(seekSeek);
   int beginSeek = seekRand.Next(0, Int32.MaxValue - length  10000);
   int[] seeks = new int[length];
   for (int i = 0; i < length; i++)
   {
    beginSeek += 10000;
    seeks[i] = beginSeek;
   }
   //生成随机数字 
   for (int i = 0; i < length; i++)
   {
    Random rand = new Random(seeks[i]);
    int pownum = 1  (int)Math.Pow(10, length);
    randMembers[i] = rand.Next(pownum, Int32.MaxValue);
   }
   //抽取随机数字 
   for (int i = 0; i < length; i++)
   {
    string numStr = randMembers[i].ToString();
    int numLength = numStr.Length;
    Random rand = new Random();
    int numPosition = rand.Next(0, numLength - 1);
    validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
   }
   //生成验证码 
   for (int i = 0; i < length; i++)
   {
    validateNumberStr += validateNums[i].ToString();
   }
   return validateNumberStr;
  }
 
  /// <summary>
  /// 2.字母验证码
  /// </summary>
  /// <param name="length">字符长度</param>
  /// <returns>验证码字符</returns>
  private string CreateAbcVerifyCode(int length)
  {
   char[] verification = new char[length];
   char[] dictionary = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
   };
   Random random = new Random();
   for (int i = 0; i < length; i++)
   {
    verification[i] = dictionary[random.Next(dictionary.Length - 1)];
   }
   return new string(verification);
  }
 
  /// <summary>
  /// 3.混合验证码
  /// </summary>
  /// <param name="length">字符长度</param>
  /// <returns>验证码字符</returns>
  private string CreateMixVerifyCode(int length)
  {
   char[] verification = new char[length];
   char[] dictionary = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
   };
   Random random = new Random();
   for (int i = 0; i < length; i++)
   {
    verification[i] = dictionary[random.Next(dictionary.Length - 1)];
   }
   return new string(verification);
  }
 
  /// <summary>
  /// 产生验证码（随机产生4-6位）
  /// </summary>
  /// <param name="type">验证码类型数字，字符，符合</param>
  /// <returns></returns>
  public string CreateVerifyCode(VerifyCodeType type)
  {
   string verifyCode = string.Empty;
   Random random = new Random();
   int length = random.Next(4, 6);
   switch (type)
   {
    case VerifyCodeType.NumberVerifyCode:
     verifyCode = GetSingleObj().CreateNumberVerifyCode(length);
     break;
    case VerifyCodeType.AbcVerifyCode:
     verifyCode = GetSingleObj().CreateAbcVerifyCode(length);
     break;
    case VerifyCodeType.MixVerifyCode:
     verifyCode = GetSingleObj().CreateMixVerifyCode(length);
     break;
   }
   return verifyCode;
  }
  #endregion
 
  #region 验证码图片
  /// <summary>
  /// 验证码图片 => Bitmap
  /// </summary>
  /// <param name="verifyCode">验证码</param>
  /// <param name="width">宽</param>
  /// <param name="height">高</param>
  /// <returns>Bitmap</returns>
  public Bitmap CreateBitmapByImgVerifyCode(string verifyCode, int width, int height)
  {
   Font font = new Font("Arial", 14, (FontStyle.Bold | FontStyle.Italic));
   Brush brush;
   Bitmap bitmap = new Bitmap(width, height);
   Graphics g = Graphics.FromImage(bitmap);
   SizeF totalSizeF = g.MeasureString(verifyCode, font);
   SizeF curCharSizeF;
   PointF startPointF = new PointF(0, (height - totalSizeF.Height) / 2);
   Random random = new Random(); //随机数产生器
   g.Clear(Color.White); //清空图片背景色 
   for (int i = 0; i < verifyCode.Length; i++)
   {
    brush = new LinearGradientBrush(new Point(0, 0), new Point(1, 1), Color.FromArgb(random.Next(255), random.Next(255), random.Next(255)), Color.FromArgb(random.Next(255), random.Next(255), random.Next(255)));
    g.DrawString(verifyCode[i].ToString(), font, brush, startPointF);
    curCharSizeF = g.MeasureString(verifyCode[i].ToString(), font);
    startPointF.X += curCharSizeF.Width;
   }
 
   //画图片的干扰线 
   for (int i = 0; i < 10; i++)
   {
    int x1 = random.Next(bitmap.Width);
    int x2 = random.Next(bitmap.Width);
    int y1 = random.Next(bitmap.Height);
    int y2 = random.Next(bitmap.Height);
    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
   }
 
   //画图片的前景干扰点 
   for (int i = 0; i < 100; i++)
   {
    int x = random.Next(bitmap.Width);
    int y = random.Next(bitmap.Height);
    bitmap.SetPixel(x, y, Color.FromArgb(random.Next()));
   }
 
   g.DrawRectangle(new Pen(Color.Silver), 0, 0, bitmap.Width - 1, bitmap.Height - 1); //画图片的边框线 
   g.Dispose();
   return bitmap;
  }
 
  /// <summary>
  /// 验证码图片 => byte[]
  /// </summary>
  /// <param name="verifyCode">验证码</param>
  /// <param name="width">宽</param>
  /// <param name="height">高</param>
  /// <returns>byte[]</returns>
  public byte[] CreateByteByImgVerifyCode(string verifyCode, int width, int height)
  {
   Font font = new Font("Arial", 14, (FontStyle.Bold | FontStyle.Italic));
   Brush brush;
   Bitmap bitmap = new Bitmap(width, height);
   Graphics g = Graphics.FromImage(bitmap);
   SizeF totalSizeF = g.MeasureString(verifyCode, font);
   SizeF curCharSizeF;
   PointF startPointF = new PointF(0, (height - totalSizeF.Height) / 2);
   Random random = new Random(); //随机数产生器
   g.Clear(Color.White); //清空图片背景色 
   for (int i = 0; i < verifyCode.Length; i++)
   {
    brush = new LinearGradientBrush(new Point(0, 0), new Point(1, 1), Color.FromArgb(random.Next(255), random.Next(255), random.Next(255)), Color.FromArgb(random.Next(255), random.Next(255), random.Next(255)));
    g.DrawString(verifyCode[i].ToString(), font, brush, startPointF);
    curCharSizeF = g.MeasureString(verifyCode[i].ToString(), font);
    startPointF.X += curCharSizeF.Width;
   }
 
   //画图片的干扰线 
   for (int i = 0; i < 10; i++)
   {
    int x1 = random.Next(bitmap.Width);
    int x2 = random.Next(bitmap.Width);
    int y1 = random.Next(bitmap.Height);
    int y2 = random.Next(bitmap.Height);
    g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
   }
 
   //画图片的前景干扰点 
   for (int i = 0; i < 100; i++)
   {
    int x = random.Next(bitmap.Width);
    int y = random.Next(bitmap.Height);
    bitmap.SetPixel(x, y, Color.FromArgb(random.Next()));
   }
 
   g.DrawRectangle(new Pen(Color.Silver), 0, 0, bitmap.Width - 1, bitmap.Height - 1); //画图片的边框线 
   g.Dispose();
 
   //保存图片数据 
   MemoryStream stream = new MemoryStream();
   bitmap.Save(stream, ImageFormat.Jpeg);
   //输出图片流 
   return stream.ToArray();
 
  }
  #endregion
 }
}

using System.DrawingCore.Imaging;
using System.IO;
using Common.Helper;
using Microsoft.AspNetCore.Mvc;
 
namespace WebApplicationApi.Controllers
{
 public class VerifyCodeController : Controller
 {
  public IActionResult Index()
  {
   return View();
  }
 
  /// <summary>
  /// 数字验证码
  /// </summary>
  /// <returns></returns>
  public FileContentResult NumberVerifyCode()
  {
   string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.NumberVerifyCode);
   byte[] codeImage = VerifyCodeHelper.GetSingleObj().CreateByteByImgVerifyCode(code, 100, 40);
   return File(codeImage, @"image/jpeg");
  }
 
  /// <summary>
  /// 字母验证码
  /// </summary>
  /// <returns></returns>
  public FileContentResult AbcVerifyCode()
  {
   string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.AbcVerifyCode);
   var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, 100, 40);
   MemoryStream stream = new MemoryStream();
   bitmap.Save(stream, ImageFormat.Png);
   return File(stream.ToArray(), "image/png");
  }
 
  /// <summary>
  /// 混合验证码
  /// </summary>
  /// <returns></returns>
  public FileContentResult MixVerifyCode()
  {
   string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.MixVerifyCode);
   var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, 100, 40);
   MemoryStream stream = new MemoryStream();
   bitmap.Save(stream, ImageFormat.Gif);
   return File(stream.ToArray(), "image/gif");
  }
 
 }
}

@{
 Layout = null;
}
<!DOCTYPE html>
<html>
<head>
 <meta name="viewport" content="width=device-width" />
 <title>Index</title>
</head>
<body>
 <figure>
  <h3>图片验证码</h3>
  <fieldset>
   <legend>数字验证码</legend>
   <img id="nubImg" title="数字验证码" src="/VerifyCode/NumberVerifyCode?random=" alt="vcode" onclick="refresh()" style="cursor:pointer;" />
  </fieldset>
  <fieldset>
   <legend>数字验证码</legend>
   <img id="abcImg" title="字母验证码" src="/VerifyCode/AbcVerifyCode" alt="vcode" onclick="this.src=this.src+'?'" style="cursor:pointer;" />
  </fieldset>
  <fieldset>
   <legend>混合验证码</legend>
   <img id="mixImg" title="数字字母混合验证码" src="/VerifyCode/MixVerifyCode" alt="vcode" onclick="this.src=this.src+'?'" style="cursor:pointer;" />
  </fieldset>
 </figure>
 
 <script type="text/javascript">
  function refresh() {
   var id = document.getElementById("nubImg");
   var str = "/VerifyCode/NumberVerifyCode?random=" + Math.random();
   id.setAttribute("src", str);
  }
 </script>
 
</body>
</html>