如何用.NET Core 2.0编写生成图片验证码的完整实例代码？

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前言：图片验证码在我们日常开发中是必不可少的功能，最近工作中就遇到了这个需求，下面将实现的方法分享给大家，不多说，直接看详细介绍。

.NET Core 实现图片验证码的方法：

1. 创建一个图片验证码类，包含以下属性： - `Width`：图片宽度 - `Height`：图片高度 - `Code`：验证码字符 - `Image`：生成的图片

2. 创建一个方法用于生成随机字符，可以包含数字、字母等： csharp private static string GenerateRandomCode(int length) { const string chars=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789; var random=new Random(); return new string(Enumerable.Repeat(chars, length) .Select(s=> s[random.Next(s.Length)]) .ToArray()); }

3. 创建一个方法用于生成图片验证码： csharp public static Image GenerateImage(int width, int height, string code) { var bitmap=new Bitmap(width, height); using (var graphics=Graphics.FromImage(bitmap)) { graphics.Clear(Color.White); graphics.DrawString(code, new Font(Arial, 20), Brushes.Black, new PointF(0, 0)); } return bitmap; }

4. 创建一个方法用于生成图片验证码对象： csharp public static ImageCode GenerateImageCode(int width, int height, int length) { var code=GenerateRandomCode(length); var image=GenerateImage(width, height, code); return new ImageCode { Width=width, Height=height, Code=code, Image=image }; }

5. 使用生成的方法： csharp var imageCode=GenerateImageCode(100, 30, 6); // 将 imageCode.Image 保存或输出到浏览器

以上是 .NET Core 实现图片验证码的基本方法，可以根据实际需求进行修改和扩展。

前言

图片验证码在我们日常开发中是必不可少会遇见的一个功能，最近工作中就遇到了这个需求，所以下面将实现的方法分享给大家，话不多说了，来一起看看详细的介绍吧。

.NET Core 2.0生成图片验证码

NuGet包引入：ZKWeb.System.Drawing，如下所示：

代码实例如下：VerifyCodeHelper

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 } }

新建控制器：VerifyCodeController，

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"); } } }

添加页面index.cshtml，如下代码：

@{ 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>

生成验证码如下所示：

总结

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