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 4.0.1

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(0, seekorigin.begin);
                stream.read(data, 0, 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(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

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, 100, 40);
            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, 100, 40);
            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, 100, 40);
            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, 100, 40);
            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, 100, 40);
            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, 100, 40);
            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。