C# 判断以rar、zip、7z为扩展名的压缩文件是否损坏，不使用引用包System.IO.Compression

可以使用以下代码判断以rar、zip、7z为扩展名的压缩文件是否损坏：

using System;
using System.IO;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string filePath = "example.rar"; // 压缩文件路径

            string extension = Path.GetExtension(filePath)?.ToLower(); // 获取文件扩展名并转换为小写

            bool isCorrupted = false; // 是否损坏

            switch (extension)
            {
                case ".rar":
                    isCorrupted = IsRarCorrupted(filePath);
                    break;
                case ".zip":
                    isCorrupted = IsZipCorrupted(filePath);
                    break;
                case ".7z":
                    isCorrupted = Is7zCorrupted(filePath);
                    break;
                default:
                    Console.WriteLine("不支持的文件格式");
                    break;
            }

            if (isCorrupted)
            {
                Console.WriteLine("文件损坏");
            }
            else
            {
                Console.WriteLine("文件正常");
            }

            Console.ReadKey();
        }

        // 判断rar文件是否损坏
        static bool IsRarCorrupted(string filePath)
        {
            using (var stream = new FileStream(filePath, FileMode.Open))
            {
                var header = new byte[7];
                while (stream.Read(header, 0, 7) > 0)
                {
                    if (header[0] == 0x52 && header[1] == 0x61 && header[2] == 0x72 && header[3] == 0x21 &&
                        header[4] == 0x1a && header[5] == 0x07 && (header[6] == 0x00 || header[6] == 0x01))
                    {
                        return false;
                    }
                    else
                    {
                        var size = BitConverter.ToInt16(header, 5);
                        stream.Seek(size, SeekOrigin.Current);
                    }
                }
            }

            return true;
        }

        // 判断zip文件是否损坏
        static bool IsZipCorrupted(string filePath)
        {
            using (var stream = new FileStream(filePath, FileMode.Open))
            {
                var buffer = new byte[22];
                if (stream.Read(buffer, 0, 22) < 22)
                {
                    return true;
                }

                if (BitConverter.ToUInt32(buffer, 0) != 0x04034b50)
                {
                    return true;
                }

                var fileNameLength = BitConverter.ToUInt16(buffer, 26);
                var extraFieldLength = BitConverter.ToUInt16(buffer, 28);
                stream.Seek(fileNameLength + extraFieldLength, SeekOrigin.Current);

                return false;
            }
        }

        // 判断7z文件是否损坏
        static bool Is7zCorrupted(string filePath)
        {
            using (var stream = new FileStream(filePath, FileMode.Open))
            {
                var buffer = new byte[6];
                if (stream.Read(buffer, 0, 6) < 6)
                {
                    return true;
                }

                var signature = BitConverter.ToUInt64(buffer, 0);
                if (signature != 0x377abcaf271c)
                {
                    return true;
                }

                var headerSize = BitConverter.ToUInt16(buffer, 4);
                stream.Seek(headerSize, SeekOrigin.Current);

                return false;
            }
        }
    }
}

注意：以上代码只能判断是否损坏，无法确定文件是否能够正常解压缩。