DotNET6在Linux环境生成验证码

发表于 2023-12-05 本文字数 14k 字阅读时长 13 分钟

# 众所周知使用 System.Drawing.Imaging 是无法在 Linux 环境生成图片的

# 因为 Linux 环境没有相关组件且会报错

The type initializer for 'Gdip' threw an exception

# 换了一个库 SkiaSharp 还找来一个帮助类

	using SkiaSharp;
	using System.Text;

	namespace Common.Helper
	{
	/// <summary>
	/// 跨平台验证码生成类
	/// https://github.com/mono/SkiaSharp/issues/1341
	/// </summary>
	public class ValidateCodeHelper
	{
	private Random objRandom = new Random();

	#region setting
	/// <summary>
	///// 验证码长度
	/// </summary>
	public int SetLength { get; set; } = 4;

	/// <summary>
	/// 验证码字符串
	/// </summary>
	public string SetVerifyCodeText { get; set; }

	/// <summary>
	/// 是否加入小写字母
	/// </summary>
	public bool SetAddLowerLetter { get; set; } = true;

	/// <summary>
	/// 是否加入大写字母
	/// </summary>
	public bool SetAddUpperLetter { get; set; } = true;

	/// <summary>
	/// 字体大小
	/// </summary>
	public int SetFontSize = 36;

	/// <summary>
	/// // 字体颜色
	/// </summary>
	public SKColor SetFontColor { get; set; } = SKColors.Blue;

	/// <summary>
	/// 字体类型
	/// </summary>
	public string SetFontFamily = "Verdana";

	/// <summary>
	/// 背景色
	/// </summary>
	public SKColor SetBackgroundColor { get; set; } = SKColors.AliceBlue;

	/// <summary>
	/// 是否加入背景线
	/// </summary>
	public bool SetIsBackgroundLine { get; set; }

	/// <summary>
	/// 前景噪点数量
	/// </summary>
	public int SetForeNoisePointCount { get; set; } = 2;

	/// <summary>
	/// 随机码的旋转角度
	/// </summary>
	public int SetRandomAngle { get; set; } = 40;

	/// <summary>
	/// 是否随机字体颜色
	/// </summary>
	public bool SetIsRandomColor { get; set; } = true;

	/// <summary>
	/// 图片宽度
	/// </summary>
	public int SetWith { get; set; } = 200;

	/// <summary>
	/// 图片高度
	/// </summary>
	public int SetHeight { get; set; } = 40;

	/// <summary>
	/// 问题验证码答案，适用于运算符
	/// </summary>
	public string VerifyCodeResult { get; private set; }
	#endregion

	#region Constructor Method
	/// <summary>
	/// ValidateCodeHelper
	/// </summary>
	/// <param name="length"></param>
	/// <param name="isOperation"></param>
	public ValidateCodeHelper(int length = 4, bool isOperation = false)
	{
	if (isOperation)
	{
	var dic = GetQuestion();
	SetVerifyCodeText = dic.Key;
	VerifyCodeResult = dic.Value;
	SetRandomAngle = 0;
	}
	else
	{
	SetLength = length;
	GetVerifyCodeText();
	}
	SetWith = SetVerifyCodeText.Length * SetFontSize;
	SetHeight = Convert.ToInt32((60.0 / 100) * SetFontSize + SetFontSize);

	InitColors();
	}
	#endregion

	#region Private Method

	/// <summary>
	/// 得到验证码字符串
	/// </summary>
	private void GetVerifyCodeText()
	{
	// 没有外部输入验证码时随机生成
	if (string.IsNullOrEmpty(SetVerifyCodeText))
	{
	StringBuilder objStringBuilder = new StringBuilder();

	// 加入数字 1-9
	for (int i = 1; i <= 9; i++)
	{
	objStringBuilder.Append(i.ToString());
	}

	// 加入大写字母 A-Z，不包括 O
	if (SetAddUpperLetter)
	{
	char temp = ' ';

	for (int i = 0; i < 26; i++)
	{
	temp = Convert.ToChar(i + 65);

	// 如果生成的字母不是 'O'
	if (!temp.Equals('O'))
	{
	objStringBuilder.Append(temp);
	}
	}
	}

	// 加入小写字母 a-z，不包括 o
	if (SetAddLowerLetter)
	{
	char temp = ' ';

	for (int i = 0; i < 26; i++)
	{
	temp = Convert.ToChar(i + 97);

	// 如果生成的字母不是 'o'
	if (!temp.Equals('o'))
	{
	objStringBuilder.Append(temp);
	}
	}
	}

	// 生成验证码字符串
	{
	int index = 0;

	for (int i = 0; i < SetLength; i++)
	{
	index = objRandom.Next(0, objStringBuilder.Length);

	SetVerifyCodeText += objStringBuilder[index];

	objStringBuilder.Remove(index, 1);
	}
	}
	}
	}

	/// <summary>
	/// 获取随机颜色
	/// </summary>
	/// <returns></returns>
	private SKColor GetRandomColor()
	{
	Random RandomNum_First = new Random((int)DateTime.Now.Ticks);

	// 对于 C# 的随机数，没什么好说的
	System.Threading.Thread.Sleep(RandomNum_First.Next(50));
	Random RandomNum_Sencond = new Random((int)DateTime.Now.Ticks)

	// 为了在白色背景上显示，尽量生成深色
	int int_Red = RandomNum_First.Next(256);
	int int_Green = RandomNum_Sencond.Next(256);
	int int_Blue = (int_Red + int_Green > 400) ? 0 : 400 - int_Red - int_Green;
	int_Blue = (int_Blue > 255) ? 255 : int_Blue;
	return SKColor.FromHsv(int_Red, int_Green, int_Blue);
	}
	#endregion

	#region Public Method
	/// <summary>
	/// 获取问题
	/// </summary>
	/// <param name="questionList"> 默认数字加减验证 & lt;/param>
	/// <returns></returns>
	public KeyValuePair<string, string> GetQuestion(Dictionary<string, string> questionList = null)
	{
	if (questionList == null)
	{
	questionList = new Dictionary<string, string>();
	var operArray = new string[] { "+", "*", "-", "/" };
	var left = objRandom.Next(0, 10);
	var right = objRandom.Next(0, 10);
	var oper = operArray[objRandom.Next(0, operArray.Length)];
	string key = string.Empty, val = string.Empty;
	switch (oper)
	{
	case "+":
	key = string.Format("{0}+{1}=?", left, right);
	val = (left + right).ToString();
	questionList.Add(key, val);
	break;
	case "*":
	key = string.Format("{0}×{1}=?", left, right);
	val = (left * right).ToString();
	questionList.Add(key, val);
	break;
	case "-":
	if (left < right)
	{
	var intTemp = left;
	left = right;
	right = intTemp;
	}
	questionList.Add(left + "-" + right + "= ?", (left - right).ToString());
	break;
	case "/":
	right = objRandom.Next(1, 10);
	left = right * objRandom.Next(1, 10);
	questionList.Add(left + "÷" + right + "= ?", (left / right).ToString());
	break;
	}
	}
	return questionList.ToList()[objRandom.Next(0, questionList.Count)];
	}
	#endregion

	#region newCode
	/// <summary>
	/// 干扰线的颜色集合
	/// </summary>
	private List<SKColor> colors { get; set; }

	/// <summary>
	/// InitColors
	/// </summary>
	public void InitColors()
	{
	colors = new List<SKColor>();
	colors.Add(SKColors.AliceBlue);
	colors.Add(SKColors.PaleGreen);
	colors.Add(SKColors.PaleGoldenrod);
	colors.Add(SKColors.Orchid);
	colors.Add(SKColors.OrangeRed);
	colors.Add(SKColors.Orange);
	colors.Add(SKColors.OliveDrab);
	colors.Add(SKColors.Olive);
	colors.Add(SKColors.OldLace);
	colors.Add(SKColors.Navy);
	colors.Add(SKColors.NavajoWhite);
	colors.Add(SKColors.Moccasin);
	colors.Add(SKColors.MistyRose);
	colors.Add(SKColors.MintCream);
	colors.Add(SKColors.MidnightBlue);
	colors.Add(SKColors.MediumVioletRed);
	colors.Add(SKColors.MediumTurquoise);
	colors.Add(SKColors.MediumSpringGreen);
	colors.Add(SKColors.LightSlateGray);
	colors.Add(SKColors.LightSteelBlue);
	colors.Add(SKColors.LightYellow);
	colors.Add(SKColors.Lime);
	colors.Add(SKColors.LimeGreen);
	colors.Add(SKColors.Linen);
	colors.Add(SKColors.PaleTurquoise);
	colors.Add(SKColors.Magenta);
	colors.Add(SKColors.MediumAquamarine);
	colors.Add(SKColors.MediumBlue);
	colors.Add(SKColors.MediumOrchid);
	colors.Add(SKColors.MediumPurple);
	colors.Add(SKColors.MediumSeaGreen);
	colors.Add(SKColors.MediumSlateBlue);
	colors.Add(SKColors.Maroon);
	colors.Add(SKColors.PaleVioletRed);
	colors.Add(SKColors.PapayaWhip);
	colors.Add(SKColors.PeachPuff);
	colors.Add(SKColors.Snow);
	colors.Add(SKColors.SpringGreen);
	colors.Add(SKColors.SteelBlue);
	colors.Add(SKColors.Tan);
	colors.Add(SKColors.Teal);
	colors.Add(SKColors.Thistle);
	colors.Add(SKColors.SlateGray);
	colors.Add(SKColors.Tomato);
	colors.Add(SKColors.Violet);
	colors.Add(SKColors.Wheat);
	colors.Add(SKColors.White);
	colors.Add(SKColors.WhiteSmoke);
	colors.Add(SKColors.Yellow);
	colors.Add(SKColors.YellowGreen);
	colors.Add(SKColors.Turquoise);
	colors.Add(SKColors.LightSkyBlue);
	colors.Add(SKColors.SlateBlue);
	colors.Add(SKColors.Silver);
	colors.Add(SKColors.Peru);
	colors.Add(SKColors.Pink);
	colors.Add(SKColors.Plum);
	colors.Add(SKColors.PowderBlue);
	colors.Add(SKColors.Purple);
	colors.Add(SKColors.Red);
	colors.Add(SKColors.SkyBlue);
	colors.Add(SKColors.RosyBrown);
	colors.Add(SKColors.SaddleBrown);
	colors.Add(SKColors.Salmon);
	colors.Add(SKColors.SandyBrown);
	colors.Add(SKColors.SeaGreen);
	colors.Add(SKColors.SeaShell);
	colors.Add(SKColors.Sienna);
	colors.Add(SKColors.RoyalBlue);
	colors.Add(SKColors.LightSeaGreen);
	colors.Add(SKColors.LightSalmon);
	colors.Add(SKColors.LightPink);
	colors.Add(SKColors.Crimson);
	colors.Add(SKColors.Cyan);
	colors.Add(SKColors.DarkBlue);
	colors.Add(SKColors.DarkCyan);
	colors.Add(SKColors.DarkGoldenrod);
	colors.Add(SKColors.DarkGray);
	colors.Add(SKColors.Cornsilk);
	colors.Add(SKColors.DarkGreen);
	colors.Add(SKColors.DarkMagenta);
	colors.Add(SKColors.DarkOliveGreen);
	colors.Add(SKColors.DarkOrange);
	colors.Add(SKColors.DarkOrchid);
	colors.Add(SKColors.DarkRed);
	colors.Add(SKColors.DarkSalmon);
	colors.Add(SKColors.DarkKhaki);
	colors.Add(SKColors.DarkSeaGreen);
	colors.Add(SKColors.CornflowerBlue);
	colors.Add(SKColors.Chocolate);
	colors.Add(SKColors.AntiqueWhite);
	colors.Add(SKColors.Aqua);
	colors.Add(SKColors.Aquamarine);
	colors.Add(SKColors.Azure);
	colors.Add(SKColors.Beige);
	colors.Add(SKColors.Bisque);
	colors.Add(SKColors.Coral);
	colors.Add(SKColors.Black);
	colors.Add(SKColors.Blue);
	colors.Add(SKColors.BlueViolet);
	colors.Add(SKColors.Brown);
	colors.Add(SKColors.BurlyWood);
	colors.Add(SKColors.CadetBlue);
	colors.Add(SKColors.Chartreuse);
	colors.Add(SKColors.BlanchedAlmond);
	colors.Add(SKColors.Transparent);
	colors.Add(SKColors.DarkSlateBlue);
	colors.Add(SKColors.DarkTurquoise);
	colors.Add(SKColors.IndianRed);
	colors.Add(SKColors.Indigo);
	colors.Add(SKColors.Ivory);
	colors.Add(SKColors.Khaki);
	colors.Add(SKColors.Lavender);
	colors.Add(SKColors.LavenderBlush);
	colors.Add(SKColors.HotPink);
	colors.Add(SKColors.LawnGreen);
	colors.Add(SKColors.LightBlue);
	colors.Add(SKColors.LightCoral);
	colors.Add(SKColors.LightCyan);
	colors.Add(SKColors.LightGoldenrodYellow);
	colors.Add(SKColors.LightGray);
	colors.Add(SKColors.LightGreen);
	colors.Add(SKColors.LemonChiffon);
	colors.Add(SKColors.DarkSlateGray);
	colors.Add(SKColors.Honeydew);
	colors.Add(SKColors.Green);
	colors.Add(SKColors.DarkViolet);
	colors.Add(SKColors.DeepPink);
	colors.Add(SKColors.DeepSkyBlue);
	colors.Add(SKColors.DimGray);
	colors.Add(SKColors.DodgerBlue);
	colors.Add(SKColors.Firebrick);
	colors.Add(SKColors.GreenYellow);
	colors.Add(SKColors.FloralWhite);
	colors.Add(SKColors.Fuchsia);
	colors.Add(SKColors.Gainsboro);
	colors.Add(SKColors.GhostWhite);
	colors.Add(SKColors.Gold);
	colors.Add(SKColors.Goldenrod);
	colors.Add(SKColors.Gray);
	colors.Add(SKColors.ForestGreen);
	}

	/// <summary>
	/// 创建画笔
	/// </summary>
	/// <param name="color"></param>
	/// <param name="fontSize"></param>
	/// <returns></returns>
	private SKPaint CreatePaint(SKColor color, float fontSize)
	{
	SkiaSharp.SKTypeface font = SKTypeface.FromFamilyName(null, SKFontStyleWeight.SemiBold, SKFontStyleWidth.ExtraCondensed, SKFontStyleSlant.Upright);
	SKPaint paint = new SKPaint();
	paint.IsAntialias = true;
	paint.Color = color;
	paint.Typeface = font;
	paint.TextSize = fontSize;
	return paint;
	}

	/// <summary>
	/// 获取验证码图片
	/// </summary>
	/// <param name="lineNum"> 干扰线数量 & lt;/param>
	/// <param name="lineStrookeWidth"> 干扰线宽度 & lt;/param>
	/// <returns></returns>
	public byte[] GetVerifyCodeImage(int lineNum = 1, int lineStrookeWidth = 1)
	{
	// 创建 bitmap 位图
	using (SKBitmap image2d = new SKBitmap(SetWith, SetHeight, SKColorType.Bgra8888, SKAlphaType.Premul))
	{
	// 创建画笔
	using (SKCanvas canvas = new SKCanvas(image2d))
	{
	// 填充背景颜色为白色
	if (SetIsRandomColor)
	{
	SetFontColor = GetRandomColor();
	}

	// 填充白色背景
	canvas.Clear(SetBackgroundColor);

	AddForeNoisePoint(image2d);
	AddBackgroundNoisePoint(image2d, canvas);

	// 将文字写到画布上
	var drawStyle = new SKPaint();
	drawStyle.IsAntialias = true;
	drawStyle.TextSize = SetFontSize;
	char[] chars = SetVerifyCodeText.ToCharArray();
	for (int i = 0; i < chars.Length; i++)
	{
	var font = SKTypeface.FromFamilyName(SetFontFamily, SKFontStyleWeight.SemiBold, SKFontStyleWidth.ExtraCondensed, SKFontStyleSlant.Upright);

	// 转动的度数
	float angle = objRandom.Next(-30, 30);

	canvas.Translate(12, 12);

	float px = ((i) * SetFontSize);
	float py = (SetHeight) / 2;

	canvas.RotateDegrees(angle, px, py);

	drawStyle.Typeface = font;
	drawStyle.Color = SetFontColor;
	// 写字 (i + 1) * 16, 28
	canvas.DrawText(chars[i].ToString(), px, py, drawStyle);
	canvas.RotateDegrees(-angle, px, py);
	canvas.Translate(-12, -12);
	}
	// 画随机干扰线
	using (SKPaint disturbStyle = new SKPaint())
	{
	Random random = new Random();
	for (int i = 0; i < lineNum; i++)
	{
	disturbStyle.Color = colors[random.Next(colors.Count)];
	disturbStyle.StrokeWidth = lineStrookeWidth;
	canvas.DrawLine(random.Next(0, SetWith), random.Next(0, SetHeight), random.Next(0, SetWith), random.Next(0, SetHeight), disturbStyle);
	}
	}
	// 返回图片 byte
	using (SKImage img = SKImage.FromBitmap(image2d))
	{
	using (SKData p = img.Encode(SKEncodedImageFormat.Png, 100))
	{
	return p.ToArray();
	}
	}
	}
	}
	}

	/// <summary>
	/// AddForeNoisePoint
	/// </summary>
	/// <param name="objBitmap"></param>
	private void AddForeNoisePoint(SKBitmap objBitmap)
	{
	for (int i = 0; i < objBitmap.Width * SetForeNoisePointCount; i++)
	{
	objBitmap.SetPixel(objRandom.Next(objBitmap.Width), objRandom.Next(objBitmap.Height), SetFontColor);
	}
	}

	/// <summary>
	/// AddBackgroundNoisePoint
	/// </summary>
	/// <param name="objBitmap"></param>
	/// <param name="objGraphics"></param>
	private void AddBackgroundNoisePoint(SKBitmap objBitmap, SKCanvas objGraphics)
	{
	using (SKPaint objPen = CreatePaint(SKColors.Azure, 0))
	{
	for (int i = 0; i < objBitmap.Width * 2; i++)
	{
	objGraphics.DrawRect(objRandom.Next(objBitmap.Width), objRandom.Next(objBitmap.Height), 1, 1, objPen);
	}
	}
	if (SetIsBackgroundLine)
	{
	// 画图片的背景噪音线
	for (var i = 0; i < 12; i++)
	{
	var x1 = objRandom.Next(objBitmap.Width);
	var x2 = objRandom.Next(objBitmap.Width);
	var y1 = objRandom.Next(objBitmap.Height);
	var y2 = objRandom.Next(objBitmap.Height);

	objGraphics.DrawLine(x1, y1, x2, y2, CreatePaint(SKColors.Silver, 0));
	}
	}
	}
	#endregion
	}
	}

# 根据 GitHub 文档装了这三个包但也还是在报错

<PackageReference Include="SkiaSharp" Version="2.88.6" />

<PackageReference Include="SkiaSharp.NativeAssets.Linux" Version="2.88.6" />

<PackageReference Include="SkiaSharp.NativeAssets.Linux.NoDependencies" Version="2.88.6" />

# 报错信息如下

The type initializer for 'SkiaSharp.SKFontManager' threw an exception.

# 最后在 GitHub 上找到了一个解决方案

GitHub

# 再添加以下两个包

	<PackageReference Include="Microsoft.Maui.Graphics" Version="8.0.3" />
	<PackageReference Include="Microsoft.Maui.Graphics.Skia" Version="8.0.3" />

# 另外 Linux 还是需要安装 libgdiplus 组件

	apt-get update
	apt-get install vim
	apt-get install -y libgdiplus && apt-get clean && ln -s /usr/lib/libgdiplus.so /usr/lib/gdiplus.dll

# 如果是 Dockerfile 的话则加最后

FROM base AS final
WORKDIR /app
RUN apt-get update -y && apt-get install -y libgdiplus && apt-get clean && ln -s /usr/lib/libgdiplus.so /usr/lib/gdiplus.dll
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "project.dll"]

# 最后大功告成并附上调用代码

验证码

	/// <summary>
	/// 获取验证码图片
	/// </summary>
	/// <param name="fileName"> 默认为空或者传值例如 1.png</param>
	/// <returns></returns>
	[HttpGet]
	public IActionResult GetVerifyCodeImage(string? fileName)
	{
	ValidateCodeHelper helper = new ValidateCodeHelper();
	var verifyCodeImage = helper.GetVerifyCodeImage(1, 1);
	return File(new MemoryStream(verifyCodeImage), "image/png", fileName);
	}

技术