使用WebRequest类下载文件

小鱼儿 2022-08-19 14:28 134阅读 0赞

using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Net;
    using System.IO;
    
    
    namespace WebRequestDownload
    {
    
        public delegate void MyDelegate(Object data);
    
        class Program
        {
            static void Main(string[] args)
            {
                string url = "http://avatar.csdn.net/E/5/A/1_u014568921.jpg";
                MyDelegate mydelegate = new MyDelegate(download);
                DateTime dateBegin=DateTime.Now;
    
                IAsyncResult result = mydelegate.BeginInvoke(url, TestCallback, dateBegin);
    
                //异步执行完成
                 mydelegate.EndInvoke(result);
    
                Console.ReadKey();
                return;
            }
    
            //异步回调函数
            public static void TestCallback(IAsyncResult data)
            {
                DateTime dateEnd = DateTime.Now;
                TimeSpan ts1 = new TimeSpan(((DateTime)data.AsyncState).Ticks);
                TimeSpan ts2 = new TimeSpan(dateEnd.Ticks);
                TimeSpan ts3 = ts1.Subtract(ts2).Duration();
                //你想转的格式
    
                Console.WriteLine("下载完成,用时{0}毫秒", ts3.TotalMilliseconds.ToString());
            }
    
    
            public static void download(Object url)
            {
                WebRequest request = WebRequest.Create(url as string);
                WebResponse response = request.GetResponse();
                Stream resStream = response.GetResponseStream();
                int bytelength = (int)response.ContentLength;
                Byte[] bytevalue = new Byte[bytelength];
                int num = 0;
                int m;
                  
                while (1 > 0)
                {
                    m = resStream.Read(bytevalue, num, bytelength);
                    if (m == 0) break;
                    num += m;           //当前已下载的字节数  
                    bytelength -= m;    //剩余字节数   总字节数：(int)response.ContentLength                              
                }
                resStream.Close();
    
                //写入文件
                string path = "Sanchez.jpg";
                FileStream fs = new FileStream(path, FileMode.Create);
    
                //将byte数组写入文件中
                fs.Write(bytevalue, 0, bytevalue.Length);
                fs.Close();
            }
        }
    }