www.pudn.com > Internet蜘蛛程序.zip > DocumentWorker.cs
using System;
using System.Net;
using System.IO;
using System.Threading;
namespace Spider
{
///
/// Perform all of the work of a single thread for the spider.
/// This involves waiting for a URL to becomve available, download
/// and then processing the page.
///
///
// 完成必须由单个工作线程执行的操作，包括
// 等待可用的URL，下载和处理页面
public class DocumentWorker
{
///
/// The base URI that is to be spidered.
///
// 要扫描的基础URI
private Uri m_uri;
///
/// The spider that this thread "works for"
///
//
private Spider m_spider;
///
/// The thread that is being used.
///
private Thread m_thread;
///
/// The thread number, used to identify this worker.
///
// 线程编号，用来标识当前的工作线程
private int m_number;
///
/// The name for default documents.
///
// 缺省文档的名字
public const string IndexFile = "index.html";
///
/// Constructor.
///
/// The spider that owns this worker.
// 构造函数，参数表示拥有当前工作线程的蜘蛛程序
public DocumentWorker(Spider spider)
{
m_spider = spider;
}
///
/// This method will take a URI name, such ash /images/blank.gif
/// and convert it into the name of a file for local storage.
/// If the directory structure to hold this file does not exist, it
/// will be created by this method.
///
/// The URI of the file about to be stored
///
/// Save a binary file to disk.
///
/// The response used to save the file
// 将二进制文件保存到磁盘
private void SaveBinaryFile(WebResponse response)
{
byte []buffer = new byte[1024];
if( m_spider.OutputPath==null )
return;
string filename = convertFilename( response.ResponseUri );
Stream outStream = File.Create( filename );
Stream inStream = response.GetResponseStream();
int l;
do
{
l = inStream.Read(buffer,0,buffer.Length);
if(l>0)
outStream.Write(buffer,0,l);
}
while(l>0);
outStream.Close();
inStream.Close();
}
///
/// Save a text file.
///
/// The text to save
// 保存文本文件
private void SaveTextFile(string buffer)
{
if( m_spider.OutputPath==null )
return;
string filename = convertFilename( m_uri );
StreamWriter outStream = new StreamWriter( filename );
outStream.Write(buffer);
outStream.Close();
}
///
/// Download a page
///
/// The data downloaded from the page
// 下载一个页面
private string GetPage()
{
WebResponse response = null;
Stream stream = null;
StreamReader reader = null;
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(m_uri);
response = request.GetResponse();
stream = response.GetResponseStream();
if( !response.ContentType.ToLower().StartsWith("text/") )
{
SaveBinaryFile(response);
return null;
}
string buffer = "",line;
reader = new StreamReader(stream);
while( (line = reader.ReadLine())!=null )
{
buffer+=line+"\r\n";
}
SaveTextFile(buffer);
return buffer;
}
catch(WebException e)
{
System.Console.WriteLine("下载失败，错误：" + e);
return null;
}
catch(IOException e)
{
System.Console.WriteLine("下载失败，错误：" + e);
return null;
}
finally
{
if( reader!=null ) reader.Close();
if( stream!=null ) stream.Close();
if( response!=null ) response.Close();
}
}
///
/// Process each link encountered. The link will be recorded
/// for later spidering if it is an http or https docuent,
/// has not been visited before(determined by spider class),
/// and is in the same host as the original base URL.
///
/// The URL to process
private void ProcessLink(string link)
{
Uri url;
// fully expand this URL if it was a relative link
try
{
url = new Uri(m_uri,link,false);
}
catch(UriFormatException e)
{
System.Console.WriteLine( "Invalid URI:" + link +" Error:" + e.Message);
return;
}
if(!url.Scheme.ToLower().Equals("http") &&
!url.Scheme.ToLower().Equals("https") )
return;
// comment out this line if you would like to spider
// the whole Internet (yeah right, but it will try)
if( !url.Host.ToLower().Equals( m_uri.Host.ToLower() ) )
return;
//System.Console.WriteLine( "Queue:"+url );
m_spider.addURI( url );
}
///
/// Process a URL
///
/// the URL to process
private void ProcessPage(string page)
{
ParseHTML parse = new ParseHTML();
parse.Source = page;
while(!parse.Eof())
{
char ch = parse.Parse();
if(ch==0)
{
Attribute a = parse.GetTag()["HREF"];
if( a!=null )
ProcessLink(a.Value);
a = parse.GetTag()["SRC"];
if( a!=null )
ProcessLink(a.Value);
}
}
}
///
/// This method is the main loop for the spider threads.
/// This method will wait for URL's to become available,
/// and then process them.
///
public void Process()
{
while(!m_spider.Quit )
{
m_uri = m_spider.ObtainWork();
m_spider.SpiderDone.WorkerBegin();
System.Console.WriteLine("Download("+this.Number+"):"+m_uri);
string page = GetPage();
if(page!=null)
ProcessPage(page);
m_spider.SpiderDone.WorkerEnd();
}
}
///
/// Start the thread.
///
public void start()
{
ThreadStart ts = new ThreadStart( this.Process );
m_thread = new Thread(ts);
m_thread.Start();
}
///
/// The thread number. Used only to identify this thread.
///
public int Number
{
get
{
return m_number;
}
set
{
m_number = value;
}
}
}
}