/// <summary>
/// 初始化爬虫
/// </summary>
/// <exception cref="ArgumentNullException">Scheduler is not null</exception>
private void InitSpider()
{
CheckRunning();
if (Scheduler == null)
{
throw new ArgumentNullException($"Scheduler is not null");
}
if (DownLoader == null)
{
throw new ArgumentNullException($"DownLoader is not null");
}
if (PageProcessor == null)
{
throw new ArgumentNullException($"PageProcessormo is not null");
}
if (Site.MinSleepTime < 500)
{
throw new SpiderExceptoin("Sleep time should be large than 500");
}
if (ThreadCount <= 0)
{
throw new ArgumentNullException($"ThreadCount should be more than one!");
}
//http并发请求限制
ServicePointManager.DefaultConnectionLimit = ThreadCount > 1024 ? ThreadCount : 1024;
SpiderListening.ForEach(item => item.AfterInit(this));
}
/// <summary>
/// 运行爬虫
/// </summary>
public void Run()
{
InitSpider();
Status = SpiderStatusEnum.Running;
var parallelOptions = new ParallelOptions {
MaxDegreeOfParallelism = ThreadCount
};
Parallel.For(0, ThreadCount, parallelOptions, i =>
{
while (Status == SpiderStatusEnum.Running)
{
Request requset = null;
try
{
requset = Scheduler.GetRequest();
if (requset == null)
{
break;
}
ProcessRequest(requset, DownLoader);
Thread.Sleep(_random.Next(Site.MinSleepTime, Site.MaxSleepTime));
}
catch (Exception e)
{
SpiderListening.ForEach(item => item.ErrorHandler(requset, e));
}
}
});
}
/// <summary>
/// 页面下载
/// </summary>
private void ProcessRequest(Request request, IDownLoader downLoader)
{
var page = downLoader.DownLoader(request, this);
PageProcessor.Process(page);
Scheduler.AddFinishRequest(request);
SpiderListening.ForEach(item => item.AfterSuccess(request));
if (page.IsSave)
{
Pipelines.ForEach(item => item.Process(page.PageResult));
}
GetPageUrl(page).ForEach(item => Scheduler.AddWaitRequest(new Request(item)));
}
/// <summary>
/// 添加监听事件
/// </summary>
/// <param name="listening">监听事件</param>
public Spider AddListening(ISpiderListening listening)
{
SpiderListening.Add(listening);
return(this);
}
