//下载时发出的事件
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace DownloadHandler
{
public delegate void DownloadStartHandler(object sender, DownloadStartEventArgs e); //声明委托
public delegate void DownloadEndHandler(object sender, DownloadEndEventArgs e);
public delegate void DownloadingHandler(object sender, DownloadingEventArgs e);
public class DownloadStartEventArgs
{
public string Url { get { return _url; } set { _url = value; } }
private string _url;
public DownloadStartEventArgs(string url) { this._url = url; }
}
public class DownloadEndEventArgs
{
public string Url { get { return _url; } set { _url = value; } }
private string _url;
public long ByteCount { get { return _byteCount; } set { _byteCount = value; } }
private long _byteCount;
public DownloadEndEventArgs(string url, long size) { this._url = url; this._byteCount = size; }
}
public class DownloadingEventArgs
{
public string Url { get { return _url; } set { _url = value; } }
private string _url;
public double Percent { get { return _percent; } set { _percent = value; } }
private double _percent;
public DownloadingEventArgs(string url, double percent) { this._url = url; this._percent = percent; }
}
public class Crawler
{
public event DownloadStartHandler DownloadStart; // 声明事件
public event DownloadEndHandler DownloadEnd; // 声明事件
public event DownloadingHandler Downloading; // 声明事件
public string Name { get { return name; } set { name = value; } }
private string name;
private string site;
public Crawler(string name, string site)
{
this.name = name;
this.site = site;
}
public void Craw()
{
while (true)
{
string url = GetNextUrl();
if (url == null) break;
long size = GetSizeOfUrl(url);
if (DownloadStart != null) //下载开始的事件发生
{
DownloadStart(this, new DownloadStartEventArgs(url));
}
for (long i = 0; i < size + 1024; i += 1024)
{
//下载数据。。。
System.Threading.Thread.Sleep(100);
double percent = (int)(i * 100.0 / size);
if (percent > 100) percent = 100;
if (Downloading != null) //下载数据的事件发生
{
Downloading(this, new DownloadingEventArgs(url, percent));
}
}
if (DownloadEnd != null) //下载结束的事件发生
{
DownloadEnd(this, new DownloadEndEventArgs(url, size));
}
}
}
private string GetNextUrl()
{
int a = rnd.Next(10);
if (a == 0) return null;
return site + "/Page" + a + ".htm";
}
private long GetSizeOfUrl(string url)
{
return rnd.Next(3000 * url.Length);
}
private Random rnd = new Random();
}
//Main
class Program
{
static void Main(string[] args)
{
Crawler crawler = new Crawler("Crawer101", "http://www.pku.edu.cn");
crawler.DownloadStart += new DownloadStartHandler(ShowStart); //注册事件
crawler.DownloadEnd += new DownloadEndHandler(ShowEnd);
crawler.Downloading += new DownloadingHandler(ShowPercent);
crawler.Craw();
}
static void ShowStart(object sender, DownloadStartEventArgs e)
{
Console.WriteLine((sender as Crawler).Name + "开始下载" + e.Url);
}
static void ShowEnd(object sender, DownloadEndEventArgs e)
{
Console.WriteLine("\n\r下载" + e.Url + "结束,其下载" + e.ByteCount + "字节");
}
static void ShowPercent(object sender, DownloadingEventArgs e)
{
Console.Write("\r下载" + e.Url + "......." + e.Percent + "%");
}
}
}
