网络爬虫C++

来源：互联网发布：女性吸毒后性反应知乎编辑：程序博客网时间：2024/05/23 02:02

写了一个网络爬虫，可以抓取网上的图片。

需要给定初始网站即可。

在vs2010中编译通过。

编译后，运行即可，有惊喜哦！！！

[cpp] view plaincopyprint?

//#include <Windows.h>
#include <string>
#include <iostream>
#include <fstream>
#include <vector>
#include "winsock2.h"
#include <time.h>
#include <queue>
#include <hash_set>
#pragma comment(lib, "ws2_32.lib")
using namespace std;
#define DEFAULT_PAGE_BUF_SIZE 1048576
queue<string> hrefUrl;
hash_set<string> visitedUrl;
hash_set<string> visitedImg;
int depth=0;
int g_ImgCnt=1;
//解析URL，解析出主机名，资源名
bool ParseURL( const string & url, string & host, string & resource){
const char * pos = strstr( url.c_str(), "http://" );
if( pos==NULL ) pos = url.c_str();
else pos += strlen("http://");
if( strstr( pos, "/")==0 )
return false;
char pHost[100];
char pResource[200];
sscanf( pos, "%[^/]%s", pHost, pResource );
host = pHost;
resource = pResource;
return true;
}
//使用Get请求，得到响应
bool GetHttpResponse( const string & url, char * &response, int &bytesRead ){
string host, resource;
if(!ParseURL( url, host, resource )){
cout << "Can not parse the url"<<endl;
return false;
}
//建立socket
struct hostent * hp= gethostbyname( host.c_str() );
if( hp==NULL ){
cout<< "Can not find host address"<<endl;
return false;
}
SOCKET sock = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP);
if( sock == -1 || sock == -2 ){
cout << "Can not create sock."<<endl;
return false;
}
//建立服务器地址
SOCKADDR_IN sa;
sa.sin_family = AF_INET;
sa.sin_port = htons( 80 );
//char addr[5];
//memcpy( addr, hp->h_addr, 4 );
//sa.sin_addr.s_addr = inet_addr(hp->h_addr);
memcpy( &sa.sin_addr, hp->h_addr, 4 );
//建立连接
if( 0!= connect( sock, (SOCKADDR*)&sa, sizeof(sa) ) ){
cout << "Can not connect: "<< url <<endl;
closesocket(sock);
return false;
};
//准备发送数据
string request = "GET " + resource + " HTTP/1.1\r\nHost:" + host + "\r\nConnection:Close\r\n\r\n";
//发送数据
if( SOCKET_ERROR ==send( sock, request.c_str(), request.size(), 0 ) ){
cout << "send error" <<endl;
closesocket( sock );
return false;
}
//接收数据
int m_nContentLength = DEFAULT_PAGE_BUF_SIZE;
char *pageBuf = (char *)malloc(m_nContentLength);
memset(pageBuf, 0, m_nContentLength);
bytesRead = 0;
int ret = 1;
cout <<"Read: ";
while(ret > 0){
ret = recv(sock, pageBuf + bytesRead, m_nContentLength - bytesRead, 0);
if(ret > 0)
{
bytesRead += ret;
}
if( m_nContentLength - bytesRead<100){
cout << "\nRealloc memorry"<<endl;
m_nContentLength *=2;
pageBuf = (char*)realloc( pageBuf, m_nContentLength); //重新分配内存
}
cout << ret <<" ";
}
cout <<endl;
pageBuf[bytesRead] = '\0';
response = pageBuf;
closesocket( sock );
return true;
//cout<< response <<endl;
}
//提取所有的URL以及图片URL
void HTMLParse ( string & htmlResponse, vector<string> & imgurls, const string & host ){
//找所有连接，加入queue中
const char *p= htmlResponse.c_str();
char *tag="href=\"";
const char *pos = strstr( p, tag );
ofstream ofile("url.txt", ios::app);
while( pos ){
pos +=strlen(tag);
const char * nextQ = strstr( pos, "\"" );
if( nextQ ){
char * url = new char[ nextQ-pos+1 ];
//char url[100]; //固定大小的会发生缓冲区溢出的危险
sscanf( pos, "%[^\"]", url);
string surl = url;
if( visitedUrl.find( surl ) == visitedUrl.end() ){
visitedUrl.insert( surl );
ofile << surl<<endl;
hrefUrl.push( surl );
}
pos = strstr(pos, tag );
delete [] url;
}
}
ofile << endl << endl;
ofile.close();
tag ="<img ";
const char* att1= "src=\"";
const char* att2="lazy-src=\"";
const char *pos0 = strstr( p, tag );
while( pos0 ){
pos0 += strlen( tag );
const char* pos2 = strstr( pos0, att2 );
if( !pos2 || pos2 > strstr( pos0, ">") )
pos = strstr( pos0, att1)+strlen(att1);
else
pos = pos2 + strlen(att2);
const char * nextQ = strstr( pos, "\"");
if( nextQ ){
char * url = new char[nextQ-pos+1];
sscanf( pos, "%[^\"]", url);
cout << url<<endl;
string imgUrl = url;
if( visitedImg.find( imgUrl ) == visitedImg.end() ){
visitedImg.insert( imgUrl );
imgurls.push_back( imgUrl );
}
pos0 = strstr(pos0, tag );
delete [] url;
}
}
cout << "end of Parse this html"<<endl;
}
//把URL转化为文件名
string ToFileName( const string &url ){
string fileName;
fileName.resize( url.size());
int k=0;
for( int i=0; i<(int)url.size(); i++){
char ch = url[i];
if( ch!='\\'&&ch!='/'&&ch!=':'&&ch!='*'&&ch!='?'&&ch!='"'&&ch!='<'&&ch!='>'&&ch!='|')
fileName[k++]=ch;
}
return fileName.substr(0,k) + ".txt";
}
//下载图片到img文件夹
void DownLoadImg( vector<string> & imgurls, const string &url ){
//生成保存该url下图片的文件夹
string foldname = ToFileName( url );
foldname = "./img/"+foldname;
if(!CreateDirectory( foldname.c_str(),NULL ))
cout << "Can not create directory:"<< foldname<<endl;
char *image;
int byteRead;
for( int i=0; i<imgurls.size(); i++){
//判断是否为图片，bmp，jgp，jpeg，gif
string str = imgurls[i];
int pos = str.find_last_of(".");
if( pos == string::npos )
continue;
else{
string ext = str.substr( pos+1, str.size()-pos-1 );
if( ext!="bmp"&& ext!="jpg" && ext!="jpeg"&& ext!="gif"&&ext!="png")
continue;
}
//下载其中的内容
if( GetHttpResponse(imgurls[i], image, byteRead)){
const char *p=image;
const char * pos = strstr(p,"\r\n\r\n")+strlen("\r\n\r\n");
int index = imgurls[i].find_last_of("/");
if( index!=string::npos ){
string imgname = imgurls[i].substr( index , imgurls[i].size() );
ofstream ofile( foldname+imgname, ios::binary );
if( !ofile.is_open() )
continue;
cout <<g_ImgCnt++<< foldname+imgname<<endl;
ofile.write( pos, byteRead- (pos-p) );
ofile.close();
}
free(image);
}
}
}
//广度遍历
void BFS( const string & url ){
char * response;
int bytes;
if( !GetHttpResponse( url, response, bytes ) ){
cout << "The url is wrong! ignore." << endl;
return;
}
string httpResponse=response;
free( response );
string filename = ToFileName( url );
ofstream ofile( "./html/"+filename );
if( ofile.is_open() ){
ofile << httpResponse << endl;
ofile.close();
}
vector<string> imgurls;
HTMLParse( httpResponse, imgurls, url );
//下载图片资源
DownLoadImg( imgurls, url );
}
void main()
{
WSADATA wsaData;
if( WSAStartup(MAKEWORD(2,2), &wsaData) != 0 ){
return;
}
CreateDirectory( "./img",0);
CreateDirectory("./html",0);
//string urlStart = "http://hao.360.cn/meinvdaohang.html";
string urlStart = "http://hao.360.cn/meinvdaohang.html";
BFS( urlStart );
visitedUrl.insert( urlStart );
while( hrefUrl.size()!=0 ){
string url = hrefUrl.front();
cout << url << endl;
BFS( url );
hrefUrl.pop();
}
WSACleanup();
return;
}

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