OMS.NET/Instructs/GetServerImgInstruct.cs

using System.Globalization;
using WebSocketSharp;

namespace OMS.NET.Instructs
{
    public class GetServerImgInstruct : Instruct
    {
        public GetServerImgInstruct()
        {
            this.Type = "get_serverImg";
        }

        public override Task Handler(string wsid)
        {
            return Task.Run(() =>
            {
                if (this.Time != null)
                {
                    //时间解析
                    string format = "yyyy-MM-dd HH:mm:ss";
                    DateTime clientDateTime = DateTime.ParseExact(this.Time, format, CultureInfo.InvariantCulture);
                    //Console.WriteLine("Converted DateTime: " + clientDateTime);
                    string serverImgPath = GlobalArea.ServerConfig.Img;
                    if (File.Exists(serverImgPath))
                    {
                        DateTime serverImgLastModified = File.GetLastWriteTime(serverImgPath);
                        Instruct res = new SendServerConfigInstruct
                        {
                            IsResponse = true
                        };
                        if (serverImgLastModified > clientDateTime)
                        {
                            byte[] imageBytes = File.ReadAllBytes(serverImgPath);
                            string imageFileType = GetImageFileType(imageBytes);
                            string base64String = $"data:image/{imageFileType};base64," + Convert.ToBase64String(imageBytes);
                            //Console.WriteLine("Base64 Encoded Image: " + base64String);
                            res.Data = new
                            {
                                @string = base64String,
                                time = serverImgLastModified.ToString(format),
                            };
                        }
                        else
                        {
                            res.Data = new
                            {
                                @string = ""
                            };
                        }
                        this.ResponseOrBroadcastInstructs.Add(res);
                    }
                }
            });
        }

        static string GetImageFileType(byte[] imageBytes)
        {
            byte[] fileHeader = imageBytes.SubArray(0, 8);

            // PNG 文件的文件头字节为 89 50 4E 47 0D 0A 1A 0A
            if (fileHeader[0] == 0x89 && fileHeader[1] == 0x50 && fileHeader[2] == 0x4E && fileHeader[3] == 0x47 &&
                fileHeader[4] == 0x0D && fileHeader[5] == 0x0A && fileHeader[6] == 0x1A && fileHeader[7] == 0x0A)
            {
                return "png";
            }

            // JPEG 文件的文件头字节为 FF D8 FF
            if (fileHeader[0] == 0xFF && fileHeader[1] == 0xD8 && fileHeader[2] == 0xFF)
            {
                return "jpeg";
            }

            return "unknown";
        }
    }

    public class SendServerImgInstruct : Instruct
    {
        public SendServerImgInstruct()
        {
            this.Type = "send_serverImg";
        }
    }
}