可借鉴的C++爬虫范本---来自网络收集

1、C++广度遍历爬某个网站的图片

#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 url，解析出主机名host，资源名resource

bool ParseURL( const string & url, string & host, string & resource)
{
if ( strlen(url.c_str()) > 2000 )
{
return false;
}

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[2000];
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; // 转换成string类型，可以自动释放内存
if( visitedUrl.find( surl ) == visitedUrl.end() ){
visitedUrl.insert( surl );
ofile << surl<<endl;
hrefUrl.push( surl );
}
pos = strstr(pos, tag );
delete [] url; // 释放掉申请的内存
}
}
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);
if(!pos) {
pos0 = strstr(att1, tag );
continue;
} else {
pos = pos + 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)){
if ( strlen(image) ==0 ) {
continue;
}
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;
// 获取网页的相应，放入response中。
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() ){
// 保存该网页的文本内容
ofile << httpResponse << endl;
ofile.close();
}
vector<string> imgurls;
//解析该网页的所有图片链接，放入imgurls里面
HTMLParse( httpResponse, imgurls, url );

//下载所有的图片资源
DownLoadImg( imgurls, url );
}

void main()
{
//初始化socket，用于tcp网络连接
WSADATA wsaData;
if( WSAStartup(MAKEWORD(2,2), &wsaData) != 0 ){
return;
}

// 创建文件夹，保存图片和网页文本文件
CreateDirectory( "./img",0);
CreateDirectory("./html",0);

string urlStart = "http://www.meituba.com/";
//string urlStart = "http://www.mzitu.com/";

// 使用广度遍历
// 提取网页中的超链接放入hrefUrl中，提取图片链接，下载图片。
BFS( urlStart );

// 访问过的网址保存起来
visitedUrl.insert( urlStart );

while( hrefUrl.size()!=0 ){
string url = hrefUrl.front(); // 从队列的最开始取出一个网址
cout << url << endl;
BFS( url ); // 遍历提取出来的那个网页，找它里面的超链接网页放入hrefUrl，下载它里面的文本，图片
hrefUrl.pop(); // 遍历完之后，删除这个网址
}
WSACleanup();
return;
}