Delphi 后端随机生成前端验证码图片程序源代码，开箱即用

Posted 2023-04-07 sensor_WU

 在前端开发的时候，常用的一个需求就是图形验证码，那么如果后端使用Delphi开发，随机生成一个验证码图片，是如何实现呢？

其实如果是VCL，就是调用TBitMap对象来实现，TBitMap有详细的Canvas操作函数，具体的操作参见Delphi的帮助文档。

直接上源代码如下：

*******************************************************
生成验证码图片： 2023-04-07
作者：sensor（老吴）QQ：910731685
将生成的图片转换成png格式，减少传输数据量。
如果是BMP图片，样本：19KB，转换成png后大小为：3KB
*******************************************************
unit uSZHN_VerifyCode;

interface
uses
  System.Classes,
  System.SysUtils,
  VCL.Graphics,
  System.UIConsts,
  System.UITypes,
  Vcl.ExtCtrls,
//  Vcl.Imaging.jpeg,
  Vcl.Imaging.pngimage,
  System.Types;

type
  // 生成验证码组件
  TSZHN_GenerateVerifyCode = class
  private const
    // 定义字典表，不要零（0），因为零和字母O样子太接近
     arrStr: array [0 .. 42] of char = (
      '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','我','爱','中','国','科','技','畅','想');
  private
    FBitmapWidth:   integer;      // 图片宽度
    FBitmapHeight:  integer;      // 图片高度
    FCodeCount:     integer;      // 取验证码字符的个数，默认是4个字符
    FFontName:      string;       // 字体名称
    FMinFontSize:   integer;      // 最小字体大小
    FRandomLineCount: integer;    // 背景随机线条数
    FXRandomLen:    integer;      // X的随机值长度
    FYRandomLen:    integer;      // Y的随机值长度
    // 画出验证码函数
    function VerifyCodeDrawImg(BMP : TBitmap): string;
  public
    constructor Create;
    procedure GetVerifyCodeAndImage(ImageStream: TStream; var VerifyCode: string);
  published
    property Width: integer           read FBitmapWidth     write FBitmapWidth;
    property Height: integer          read FBitmapHeight    write FBitmapHeight;
    property CodeCount: integer       read FCodeCount       write FCodeCount;
    property MinFontSize: integer     read FMinFontSize     write FMinFontSize;
    property RandomLineCount: integer read FRandomLineCount write FRandomLineCount;
    property XRandomLen: integer      read FXRandomLen      write FXRandomLen;
    property YRandomLen: integer      read FYRandomLen      write FYRandomLen;
  end;


//外部调用函数,  ImageStream 参数返回的是生成的验证码图片数据流，结果为验证码字符串
function Create_VerifyCode(ImageStream: TStream): string;


implementation

//外部调用函数,  ImageStream 参数返回的是生成的验证码图片数据流，结果为验证码字符串
function Create_VerifyCode(ImageStream: TStream): string;
var
  SZHN_GenerateVerifyCode : TSZHN_GenerateVerifyCode;
begin
  SZHN_GenerateVerifyCode := TSZHN_GenerateVerifyCode.Create;
  try
    SZHN_GenerateVerifyCode.GetVerifyCodeAndImage(ImageStream, Result);
  finally
    SZHN_GenerateVerifyCode.Free;
  end;

end;


constructor TSZHN_GenerateVerifyCode.Create();
begin
  inherited;
  FBitmapWidth      := 120;
  FBitmapHeight     := 40;
  FCodeCount        := 4;
  FMinFontSize      := 4;
  FRandomLineCount  := 10;
  FXRandomLen       := 5;
  FYRandomLen       := 4;
end;

// 获取验证码和图片的流数据
procedure TSZHN_GenerateVerifyCode.GetVerifyCodeAndImage(ImageStream: TStream;
  var VerifyCode: string);
var
  BMP : TBitmap;
  PNG : TPNGImage;
begin
  BMP := TBitmap.Create;
  PNG := TPNGImage.Create;
  try
    // 默认 宽120，高40
    BMP.Width := FBitmapWidth;
    BMP.Height:= FBitmapHeight;

    //画验证码图，返回的是图形字符串
    VerifyCode := VerifyCodeDrawImg(BMP);

    //转换成png格式
    PNG.Assign(BMP);
    PNG.CompressionLevel := 9;          //最高压缩率  0..9
    PNG.SaveToStream(ImageStream);      //保存成 Stream ，以便可以传递给前端(Base64)

  finally
    FreeAndNil(BMP);
    FreeAndNil(PNG);
  end;

end;

// 画出验证码函数
function TSZHN_GenerateVerifyCode.VerifyCodeDrawImg(BMP : TBitmap): string;
var
  I, j, k: integer;
  X, Y, W, H: integer;
  vLeft: integer;
  strResult: string;

  //随机颜色函数
  function RandomColor : TColor;
  begin
    Result := Random($FF) shl 16 + Random($FF) shl 8 + Random($FF);
  end;
  //随机生成字体名字，内置6种字体随机切换
  function Random_FontName: string;
  var
    FontNames : Tarray<string>;
  begin
    SetLength(FontNames,6);
    FontNames[0] := 'Microsoft JhengHei UI';
    FontNames[1] := '宋体';
    FontNames[2] := 'Microsoft YaHei UI';
    FontNames[3] := 'Ink Free';
    FontNames[4] := 'Malgun Gothic';
    FontNames[5] := 'Cascadia Code';
    Randomize;
    Result := FontNames[Random(1000000) mod 6];
  end;

begin
  // 随机获取字符，默认4个字符
  For j := 1 to FCodeCount do
  begin
    Randomize;
    k := Random(1000000) mod 43;
    strResult := strResult + trim(arrStr[k]);
  end;
  vLeft := 5;
  //设置背景颜色
  BMP.Canvas.Brush.Style := bsSolid;
  BMP.Canvas.Brush.Color := RandomColor;
  BMP.Canvas.FillRect(TRect.Create(0, 0, FBitmapWidth, FBitmapHeight));

  // 随机画10条线
  for j := 1 to FRandomLineCount do
  begin
    Randomize;
    BMP.Canvas.Brush.Style := bsCross;
    BMP.Canvas.Pen.Color := RandomColor;
    BMP.Canvas.Pen.Width := 1;
    BMP.Canvas.Pen.Mode  := pmXor;

    BMP.Canvas.MoveTo(Random(FBitmapWidth), Random(FBitmapHeight));
    BMP.Canvas.LineTo(Random(FBitmapWidth), Random(FBitmapHeight));
  end;

  for I := 1 to length(strResult) do
  begin
    Randomize;
    // 随机字体颜色，这里暂时不用每个字符一个随机颜色
    BMP.Canvas.Font.Color := RandomColor;
    //设置字体名字
    BMP.Canvas.Font.Name := Random_FontName;
    // 字体大小
    BMP.Canvas.Font.Size := Random(8) + FMinFontSize;
    if BMP.Canvas.Font.Size < (FMinFontSize + 5) then
      BMP.Canvas.Font.Size := BMP.Canvas.Font.Size + 5;
    if Random(2) = 1 then
      BMP.Canvas.Font.Style := [TFontStyle.fsBold]
    else
      BMP.Canvas.Font.Style := [TFontStyle.fsItalic];
    begin
      X := Random(FXRandomLen) + vLeft;
      Y := Random(FYRandomLen);
      W := BMP.Canvas.TextWidth(strResult[I]);
      H := BMP.Canvas.TextHeight(strResult[I]);

      BMP.Canvas.TextOut(X,Y,strResult[I]);
      vLeft := X + W + 1;
    end;
  end;
  Result := strResult; // 返回值 ，验证码字符串
end;

end.

具体使用代码：

uses
   uSZHN_VerifyCode;
var
   sVerifyCode : string;  //验证码字符串
   TM : TMemoryStream;    //验证码图片数据流信息
begin
   TM := TMemoryStream.Create;
   sVerifyCode := Create_VerifyCode(TM);
   TM.SaveToFile('C:\\Temp\\1.png');   //可以保存成文件
   Image1.Picture.LoadFromFile('C:\\Temp\\1.png');  //可以直接在Image1中显示出来
   TM.Free;
end;

asp.net core配合vue实现后端验证码逻辑

概述

网上的前端验证码逻辑总感觉不安全，验证码建议还是使用后端配合验证。
如果产品确定可以上网的话，就可以使用腾讯，百度等第三方验证，对接方便。但是产品可能内网部署，就必须自己写了。
本文章就是基于这一点来实现的。
前端验证码显示一个图片，后端生成图片。

部分原理

1.前端调用生端获取图片时，传入一个roomID，后端生成一个4位验征码，放入redis中。然后生成一个图片返回。
2.前端显示图片，登录时将roomID和填写的验证码，一并提交，登录接口根据roomId从redis中取出验证码判断是否正确。

这样就相当于后端验证了。

大家觉得有问题什么，可以进行评论。谢谢。

源码

前端部分代码

<template>
  <div class="login-container">
    <vue-particles
      color="#ffffff"
      :particleOpacity="0.7"
      :particlesNumber="50"
      shapeType="circle"
      :particleSize="4"
      linesColor="#dedede"
      :linesWidth="1"
      :lineLinked="true"
      :lineOpacity="0.4"
      :linesDistance="150"
      :moveSpeed="2"
      :hoverEffect="true"
      hoverMode="grab"
      :clickEffect="true"
      clickMode="push"
    ></vue-particles>
    <el-form ref="loginForm" :model="loginForm" :rules="loginRules" class="login-form" autocomplete="on" label-position="left">
      <div class="title-container">
        <h3 class="title">智能综合管理系统</h3>
      </div>

      <el-form-item prop="username">
        <span class="svg-container">
          <svg-icon icon-class="user" />
        </span>
        <el-input ref="username" v-model="loginForm.username" placeholder="用户名" name="username" type="text" tabindex="1" autocomplete="on" />
      </el-form-item>

      <el-tooltip v-model="capsTooltip" content="Caps lock is On" placement="right" manual>
        <el-form-item prop="password">
          <span class="svg-container">
            <svg-icon icon-class="password" />
          </span>
          <el-input
            :key="passwordType"
            ref="password"
            v-model="loginForm.password"
            :type="passwordType"
            placeholder="密码"
            name="password"
            tabindex="2"
            autocomplete="on"
            @keyup.native="checkCapslock"
            @blur="capsTooltip = false"
            @keyup.enter.native="handleLogin"
          />
          <span class="show-pwd" @click="showPwd">
            <svg-icon :icon-class="passwordType === \'password\' ? \'eye\' : \'eye-open\'" />
          </span>
        </el-form-item>
      </el-tooltip>
      <el-form-item prop="yzm">
        <span class="svg-container">
          <svg-icon icon-class="password" />
        </span>
        <el-input type="text" v-model="loginForm.verifyCode" maxlength="4" placeholder="验证码" />
        <div class="identifyCode" @click="refreshCode">
          <el-image :src="verifyImageUrl"></el-image>
        </div>
      </el-form-item>
      <el-button :loading="loading" type="primary" style="width: 100%; margin-bottom: 30px" @click.native.prevent="handleLogin">登录</el-button>
    </el-form>
  </div>
</template>

<script>
import { validUsername } from \'@/utils/validate\'
import Identify from \'./components/Identify\'
import { uuid } from \'vue-uuid\'; // uuid object is also exported to things
// outside Vue instance.


export default {
  name: \'Login\',
  components: { Identify },
  data() {
    const validateUsername = (rule, value, callback) => {
      if (!validUsername(value)) {
        callback(new Error(\'请输入正确的用户名\'))
      } else {
        callback()
      }
    }
    const validatePassword = (rule, value, callback) => {
      if (value.length < 6) {
        callback(new Error(\'密码最少6位\'))
      } else {
        callback()
      }
    }
    return {
      loginForm: {
        username: \'admin\',
        password: \'111111\',
        roomId: \'\',
        verifyCode: \'\'
      },
      loginRules: {
        username: [{ required: true, trigger: \'blur\', validator: validateUsername }],
        password: [{ required: true, trigger: \'blur\', validator: validatePassword }]
      },
      passwordType: \'password\',
      capsTooltip: false,
      loading: false,
      showDialog: false,
      redirect: undefined,
      otherQuery: {},
      identifyCodes: \'1234567890\',
      identifyCode: \'\',
      // verifyImageRoomId: \'\',
      verifyImageUrl: \'\',
    }
  },
  watch: {
    $route: {
      handler: function (route) {
        const query = route.query
        if (query) {
          this.redirect = query.redirect
          this.otherQuery = this.getOtherQuery(query)
        }
      },
      immediate: true
    }
  },
  created() {
    // window.addEventListener(\'storage\', this.afterQRScan)
    // this.identifyCode = \'\'
    // this.makeCode(this.identifyCodes, 4)
    this.refreshCode()
  },
  mounted() {
    if (this.loginForm.username === \'\') {
      this.$refs.username.focus()
    } else if (this.loginForm.password === \'\') {
      this.$refs.password.focus()
    }
  },
  destroyed() {
    // window.removeEventListener(\'storage\', this.afterQRScan)
  },
  methods: {
    checkCapslock(e) {
      const { key } = e
      this.capsTooltip = key && key.length === 1 && (key >= \'A\' && key <= \'Z\')
    },
    showPwd() {
      if (this.passwordType === \'password\') {
        this.passwordType = \'\'
      } else {
        this.passwordType = \'password\'
      }
      this.$nextTick(() => {
        this.$refs.password.focus()
      })
    },
    createUuid() {
      let uuidV4 = uuid.v4().replace(\'-\', \'\').replace(\'-\', \'\').replace(\'-\', \'\').replace(\'-\', \'\')

      this.verifyImageRoomId = uuidV4
      this.verifyImageUrl = \'/api/Operator/getCaptchaImage/120/40/\' + this.verifyImageRoomId
      console.log(uuidV4)
    },
    handleLogin() {
      this.$refs.loginForm.validate(valid => {
        if (valid) {
          this.loading = true
          this.$store.dispatch(\'user/login\', this.loginForm)
            .then(() => {
              this.$router.push({ path: this.redirect || \'/\', query: this.otherQuery })
              this.loading = false
            })
            .catch(() => {
              this.loading = false
            })
        } else {
          console.log(\'error submit!!\')
          return false
        }
      })
    },
    getOtherQuery(query) {
      return Object.keys(query).reduce((acc, cur) => {
        if (cur !== \'redirect\') {
          acc[cur] = query[cur]
        }
        return acc
      }, {})
    },
    // 生成随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min)
    },
    // 切换验证码
    refreshCode() {
      let uuidV4 = uuid.v4().replace(\'-\', \'\').replace(\'-\', \'\').replace(\'-\', \'\').replace(\'-\', \'\')

      this.loginForm.roomId = uuidV4
      this.verifyImageUrl = \'/api/Operator/getCaptchaImage/120/40/\' + this.loginForm.roomId
      console.log(uuidV4)
    },
    // 生成四位随机验证码
    makeCode(o, l) {
      for (let i = 0; i < l; i++) {
        this.identifyCode += this.identifyCodes[
          this.randomNum(0, this.identifyCodes.length)
        ]
      }
      console.log(this.identifyCode)
    }
  }
}
</script>

<style lang="scss">
/* 修复input 背景不协调 和光标变色 */
/* Detail see https://github.com/PanJiaChen/vue-element-admin/pull/927 */

$bg: #283443;
$light_gray: #fff;
$cursor: #fff;

@supports (-webkit-mask: none) and (not (cater-color: $cursor)) {
  .login-container .el-input input {
    color: $cursor;
  }
}

/* reset element-ui css */
.login-container {
  background: url("~@/assets/background.jpg") no-repeat;
  min-height: 100vh;

  .el-input {
    display: inline-block;
    height: 47px;
    width: 85%;

    input {
      background: transparent;
      border: 0px;
      -webkit-appearance: none;
      border-radius: 0px;
      padding: 12px 5px 12px 15px;
      color: $light_gray;
      height: 47px;
      caret-color: $cursor;

      &:-webkit-autofill {
        box-shadow: 0 0 0px 1000px $bg inset !important;
        -webkit-text-fill-color: $cursor !important;
      }
    }
  }

  .el-form-item {
    border: 1px solid rgba(255, 255, 255, 0.1);
    background: rgba(0, 0, 0, 0.1);
    border-radius: 5px;
    color: #454545;

    .el-form-item__error {
      color: rgb(223, 223, 176);
    }
  }
}
</style>

<style lang="scss" scoped>
$bg: #2d3a4b;
$dark_gray: #889aa4;
$light_gray: #eee;

.login-container {
  min-height: 100%;
  width: 100%;
  background-color: $bg;
  overflow: hidden;

  .login-form {
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    margin: auto;
    width: 520px;
    max-width: 100%;
    padding: 160px 35px 0;
    margin: 0 auto;
    overflow: hidden;
  }

  .tips {
    font-size: 14px;
    color: #fff;
    margin-bottom: 10px;

    span {
      &:first-of-type {
        margin-right: 16px;
      }
    }
  }

  .svg-container {
    padding: 6px 5px 6px 15px;
    color: $dark_gray;
    vertical-align: middle;
    width: 30px;
    display: inline-block;
  }

  .title-container {
    position: relative;

    .title {
      font-size: 42px;
      color: $light_gray;
      margin: 0px auto 40px auto;
      text-align: center;
      font-weight: bold;
    }
  }

  .show-pwd {
    position: absolute;
    right: 10px;
    top: 7px;
    font-size: 16px;
    color: $dark_gray;
    cursor: pointer;
    user-select: none;
  }
  .identifyCode {
    position: absolute;
    right: 10px;
    top: 5px;
  }

  .thirdparty-button {
    position: absolute;
    right: 0;
    bottom: 6px;
  }

  @media only screen and (max-width: 470px) {
    .thirdparty-button {
      display: none;
    }
  }
}
</style>

后端接口

        /// <summary>
        /// 获取验证码
        /// </summary>
        /// <returns></returns>
        [HttpGet("getCaptchaImage/{width:int}/{height:int}/{roomId}")]
        public IActionResult GetCaptchaImage(int width, int height, string roomId)
        {
            Console.WriteLine(roomId);
            //int width = 100;
            //int height = 36;
            var captchaCode = Captcha.GenerateCaptchaCode();
            var result = Captcha.GenerateCaptchaImage(width, height, captchaCode);
            string redisKey = "VerifyCode_" + roomId;
            Startup.redisDb.StringSet(redisKey, captchaCode, new TimeSpan(0, 5, 0));
            Stream s = new MemoryStream(result.CaptchaByteData);
            return new FileStreamResult(s, "image/png");
        }

        /// <summary>
        /// 登录
        /// </summary>
        /// <returns></returns>
        [HttpPost("login")]
        public ApiResponseData Login(LoginDto loginInfo)
        {
            if (string.IsNullOrWhiteSpace(loginInfo.username))
                return ApiResponse.Error("用户名不能为空");
            if (string.IsNullOrWhiteSpace(loginInfo.password))
                return ApiResponse.Error("密码不能为空");

            Entity.BaseOperator operInfo = Db
                .Select<BaseOperator>()
                .Where(a => a.OperatorCode == loginInfo.username && a.Password == loginInfo.password.ToLower() && a.Status == 1 && a.IsDel == false).ToOne();
            if (operInfo == null)
                return ApiResponse.Error("用户名或者密码不正确");

            bool verifyResult = Captcha.ValidateCaptchaCode(loginInfo.RoomId, loginInfo.VerifyCode);
            if(verifyResult == false)
                return ApiResponse.Error("验证码不正确");

            //登录时重新生成token，一个用户只能在一个地方登录
            string token = System.Guid.NewGuid().ToString().Replace("-", "");
            Db.Update<BaseOperator>(operInfo.OperatorId)
                .Set(a => a.Token, token)
                .ExecuteAffrows();

            dynamic outJson = new ExpandoObject();//初始化一个不包含任何成员的ExpandoObject
            outJson.token = token;

            //存入redis
            string redisKey = "UserInfo_" + token;
            Startup.redisDb.StringSet(redisKey, operInfo.OperatorId, new TimeSpan(24, 0, 0));

            return ApiResponse.Succ(outJson);
        }