务必收藏备用：.net core中通过Json或直接获取图形验证码（数字验证码、字母验证码、混合验证码），有源代码全实战demo（开源代码.net core3.0）

很多人写的博客大家看了会一知半解，不知道怎么用，应该引用什么类库或者代码不全，这样很多小白很是头疼，尤其是尝新技术更是如此。我们这边不止告诉你步骤，而且还提供开源demo。随着时间的推移，我们的demo库会日益强大请及时收藏GitHub。

1.首先你需要Nuget引用类库

Install-Package ZKWeb.System.Drawing -Version 4.0.

2.创建公共类VerifyCodeHelper和CommonHelper

（1）CommonHelper中添加图形处理方法

#region 验证码
        public static byte[] Bitmap2Byte(Bitmap bitmap)
        {
            using (MemoryStream stream = new MemoryStream())
            {
                bitmap.Save(stream, ImageFormat.Jpeg);
                byte[] data = new byte[stream.Length];
                stream.Seek(, SeekOrigin.Begin);
                stream.Read(data, , Convert.ToInt32(stream.Length));
                return data;
            }
        }
        #endregion
public static string CodeJson(string code, string msg)
        {
            return "{\"code\":\"" + code + "\",\"msg\":\"" + msg + "\"}";
        }

（2）VerifyCodeHelper添加图形处理方法

public  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(, Int32.MaxValue - length * );
            int[] seeks = new int[length];
            for (int i = ; i < length; i++)
            {
                beginSeek += ;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = ; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum =  * (int)Math.Pow(, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = ; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(, numLength - );
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, ));
            }
            //生成验证码
            for (int i = ; 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 = ; i < length; i++)
            {
                verification[i] = dictionary[random.Next(dictionary.Length - )];
            }
            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',
                '', '', '', '', '', '', '', '', '', '',
                '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 = ; i < length; i++)
            {
                verification[i] = dictionary[random.Next(dictionary.Length - )];
            }
            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(, );
            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", , (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(, (height - totalSizeF.Height) / );
            Random random = new Random(); //随机数产生器
            g.Clear(Color.White); //清空图片背景色
            for (int i = ; i < verifyCode.Length; i++)
            {
                brush = new LinearGradientBrush(new Point(, ), new Point(, ), Color.FromArgb(random.Next(), random.Next(), random.Next()), Color.FromArgb(random.Next(), random.Next(), random.Next()));
                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 = ; i < ; 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 = ; i < ; 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), , , bitmap.Width - , bitmap.Height - ); //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", , (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(, (height - totalSizeF.Height) / );
            Random random = new Random(); //随机数产生器
            g.Clear(Color.White); //清空图片背景色
            for (int i = ; i < verifyCode.Length; i++)
            {
                brush = new LinearGradientBrush(new Point(, ), new Point(, ), Color.FromArgb(random.Next(), random.Next(), random.Next()), Color.FromArgb(random.Next(), random.Next(), random.Next()));
                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 = ; i < ; 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 = ; i < ; 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), , , bitmap.Width - , bitmap.Height - ); //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

3.后台控制器根据请求返回相应图形数据

 #region 验证码

        #region 混合验证码

        [HttpGet]
        public string MixVerifyCodeJson()
        {
            string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.MixVerifyCode);
            var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, , );
            byte[] imgBt = CommonHelper.Bitmap2Byte(bitmap);
            string uuid = Guid.NewGuid().ToString();
            return CommonHelper.CodeJson(uuid, Convert.ToBase64String(imgBt));
        }
        [HttpGet]
        public IActionResult MixVerifyCode()
        {
            string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.MixVerifyCode);
            var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, , );
            MemoryStream stream = new MemoryStream();
            bitmap.Save(stream, ImageFormat.Png);
            return File(stream.ToArray(), "image/png");
        }
        #endregion

        #region 数字验证码
        [HttpGet]
        public string NumberVerifyCodeJson()
        {
            string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.NumberVerifyCode);
            var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, , );
            byte[] imgBt = CommonHelper.Bitmap2Byte(bitmap);
            string uuid = Guid.NewGuid().ToString();
            return CommonHelper.CodeJson(uuid, Convert.ToBase64String(imgBt));
        }
        [HttpGet]
        public IActionResult NumberVerifyCode()
        {
            string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.NumberVerifyCode);
            var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, , );
            MemoryStream stream = new MemoryStream();
            bitmap.Save(stream, ImageFormat.Png);
            return File(stream.ToArray(), "image/png");
        }
        #endregion

        #region 字母验证码
        [HttpGet]
        public IActionResult AbcVerifyCode()
        {
            string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.AbcVerifyCode);
            var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, , );
            MemoryStream stream = new MemoryStream();
            bitmap.Save(stream, ImageFormat.Png);
            return File(stream.ToArray(), "image/png");
        }
        [HttpGet]
        public string AbcVerifyCodeJson()
        {
            string code = VerifyCodeHelper.GetSingleObj().CreateVerifyCode(VerifyCodeHelper.VerifyCodeType.AbcVerifyCode);
            var bitmap = VerifyCodeHelper.GetSingleObj().CreateBitmapByImgVerifyCode(code, , );
            byte[] imgBt = CommonHelper.Bitmap2Byte(bitmap);
            string uuid = Guid.NewGuid().ToString();
            return CommonHelper.CodeJson(uuid, Convert.ToBase64String(imgBt));
        }
        #endregion

        #endregion

4.前端请求分为直接请求文件或json图形数据并渲染至Img标签

<script type="text/javascript">
    $(function () {
        refreshNumJson();
        refreshMixJson();
        refreshAbcJson();
    });
    function refreshNum() {
        var id = document.getElementById("numImg");
        var str = "/Verify/NumberVerifyCode?random=" + Math.random();
        id.setAttribute("src", str);
    }
    function refreshNumJson() {
        $.ajax({
            type: "get",
            contentType: 'application/json',
            url: '/Verify/NumberVerifyCodeJson?' + Math.random(),
            dataType: 'json',
            async: false,
            success: function (data) {
                $("#numImgJson").attr("src", "data:image/png;base64," + data.msg);
                console.log(data.code);
            },
            error: function (xhr) {
                console.log(xhr.responseText);
            }
        });
    }

    function refreshMix() {
        var id = document.getElementById("mixImg");
        var str = "/Verify/MixVerifyCode?random=" + Math.random();
        id.setAttribute("src", str);
    }
    function refreshMixJson() {
        $.ajax({
            type: "get",
            contentType: 'application/json',
            url: '/Verify/MixVerifyCodeJson?' + Math.random(),
            dataType: 'json',
            async: false,
            success: function (data) {
                $("#mixImgJson").attr("src", "data:image/png;base64," + data.msg);
                console.log(data.code);
            },
            error: function (xhr) {
                console.log(xhr.responseText);
            }
        });
    }

    function refreshAbc() {
        var id = document.getElementById("abcImg");
        var str = "/Verify/AbcVerifyCode?random=" + Math.random();
        id.setAttribute("src", str);
    }
    function refreshAbcJson() {
        $.ajax({
            type: "get",
            contentType: 'application/json',
            url: '/Verify/AbcVerifyCodeJson?' + Math.random(),
            dataType: 'json',
            async: false,
            success: function (data) {
                $("#abcImgJson").attr("src", "data:image/png;base64," + data.msg);
                console.log(data.code);
            },
            error: function (xhr) {
                console.log(xhr.responseText);
            }
        });
    }
</script>

<h2>图形数字验证码</h2>
<img id="numImgJson" title="数字验证码Json获取"
     alt="vcode" style="cursor:pointer;" onclick="refreshNumJson()" />
<a href="javascript:void(0);" onclick="refreshNumJson()">看不清，换一张</a>
<img id="numImg" title="数字验证码" src="/Verify/NumberVerifyCode?random=1994"
     alt="vcode" style="cursor:pointer;" onclick="refreshNum()" />
<a href="javascript:void(0);" onclick="refreshNum()">看不清，换一张</a>
<h2>图形字母验证码</h2>
<img id="abcImgJson" title="图形字母验证码Json获取"
     alt="vcode" style="cursor:pointer;" onclick="refreshAbcJson()" />
<a href="javascript:void(0);" onclick="refreshAbcJson()">看不清，换一张</a>
<img id="abcImg" title="图形字母验证码" src="/Verify/AbcVerifyCode?random=1994"
     alt="vcode" style="cursor:pointer;" onclick="refreshAbc()" />
<a href="javascript:void(0);" onclick="refreshAbc()">看不清，换一张</a>
<h2>图形混合验证码</h2>
<img id="mixImgJson" title="图形混合验证码Json获取"
     alt="vcode" style="cursor:pointer;" onclick="refreshMixJson()" />
<a href="javascript:void(0);" onclick="refreshMixJson()">看不清，换一张</a>
<img id="mixImg" title="图形混合验证码" src="/Verify/MixVerifyCode?random=1994"
     alt="vcode" style="cursor:pointer;" onclick="refreshMix()" />
<a href="javascript:void(0);" onclick="refreshMix()">看不清，换一张</a>

5.效果如图

开源地址 动动小手，点个推荐吧！

注意：我们机遇屋该项目将长期为大家提供asp.net core各种好用demo，旨在帮助.net开发者提升竞争力和开发速度，建议尽早收藏该模板集合项目。