.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);
 //

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="https://www.gxlcms.com/VerifyCode/NumberVerifyCode?random=" 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="https://www.gxlcms.com/VerifyCode/AbcVerifyCode" 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="https://www.gxlcms.com/VerifyCode/MixVerifyCode" 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>