C# 网络下载器

namespace WebDownLoad
{
    // 一个下载任务类
    public class DownLoadTask
    {
 
        public async Task Start(string url,string targetUrl)
        {
            try
            {
                // 1.先创建一个HttpClient连接
                // 由于HttpClient实现了IDispose接口，所以我们可以回收它的资源
                using HttpClient client = new HttpClient();
                // 1.1.某些网站会反爬，所以我们需要设置一些参数
                client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36 Edg/118.0.2088.61");
 
                // 2.进行异步请求
                HttpResponseMessage  response = await client.GetAsync(url);
                // 3.请求成功
                if (response.IsSuccessStatusCode)
                {
                    // 3.1.读取文件的类型
                    string? type = response.Content.Headers.ContentType?.MediaType;
                    // 3.2.文件的总大小
                    long? totalSize = response.Content.Headers.ContentLength;
 
                    // 3.3.获取文件流
                    // 缓存区的大小为 10 kb
                    // 当前下载的大小
                    long downloadSize = 0;
                    int length = 0;
 
                    using BufferedStream bufferedStream = new BufferedStream(
                        await response.Content.ReadAsStreamAsync());
                    // 缓冲区大小 0.5KB
                    byte[] bufferSize = new byte[1024];
                    IEnumerable<byte> targetBuffer = new List<byte>();
                    string suffix = GetType(type);
                    while ((length = bufferedStream.Read(bufferSize, 0, bufferSize.Length)) != 0)
                    {
                        downloadSize += length;
                        long? progress = downloadSize * 100 / totalSize ;
                        targetBuffer = targetBuffer.Concat(bufferSize.ToList());
                        await Console.Out.WriteAsync($"\r下载中{progress}%");
                    }
                    await Console.Out.WriteLineAsync();
                    File.WriteAllBytes(targetUrl + Random.Shared.Next(10, 10000) + suffix, targetBuffer.ToArray());
                }
                // 4.请求失败
                else
                {
                    Console.WriteLine("请求下载失败");
                }
 
            }catch (HttpRequestException e)
            {
                Console.WriteLine($"请求下载失败：{e.Message}");
            }
        }
 
 // 检测文件的类型
        private string GetType(string type) {
            string suffix = "";
            if (type.Contains("jpeg"))
            {
                suffix = ".jpg";
            }
            else if (type.Contains("application/octet-stream"))
            {
                suffix = ".exe";
            }
            else if (type.Contains("png"))
            {
                suffix = ".png";
            }
            else if (type.Contains("mp4"))
            {
                suffix = ".mp4";
            }
            else if (type.Contains("avi"))
            {
                suffix = ".avi";
            }
            else if (type.Contains("mp3"))
            {
                suffix = ".mp3";
            }
            else if (type.Contains("mpeg"))
            {
                suffix = ".m4a";
            }
            return suffix;
        }
    }
}

using WebDownLoad;
 
namespace WebDownLoad
{
    public class Program
    {
        public async static Task Main(string[] args) {
 
            while (true)
            {
                Console.WriteLine("请输入下载地址(如果输入0退出):");
                string url = Console.ReadLine();
 
                if ("0".Equals(url))
                {
                    break;
                }
                DownLoadTask task = new DownLoadTask();
                task.Start(url, "E:\\网络下载\\");
            }
        }
 
    }
}