先来说一下主要的技术点：
1.输入起始网址，使用
2.使用
3.下载图片至创建的文件夹中，，同时其他的urlpush进队列。
4.为了使爬虫能够连续的工作，这里使用了
下面附上技术点的学习资料供参考：
ssanf函数的用法：
C++11正则表达式
http协议：
Socket编程：
另外，这个小爬虫结构简陋，还存在很多不足，例如队列中的
/*下载图片 C++ Winsock 网络编程*/#define _CRT_SECURE_NO_WARNINGS //vs 2013用于忽略c语言安全性警告#include <cstdio>#include <iostream>#include <fstream>#include <string>#include <cstring>#include <regex>#include <vector>#include <queue>#include <algorithm>#include <winsock2.h>#include <map>using namespace std;#pragma comment(lib, "ws2_32.lib")char host[500];int num = 1;char othPath[800];string allHtml;vector <string> photoUrl;vector <string> comUrl;map <string, int> mp; //防止相同网址重复遍历SOCKET sock;bool analyUrl(char *url) //仅支持http协议,解析出主机和IP地址{char *pos = strstr(url, "");if (pos == NULL)return false;elsepos += 7;sscanf(pos, "%[^/]%s", host, othPath); //http:// 后一直到/之前的是主机名cout << "host: " << host << " repath:" << othPath << endl;return true;}void regexGetimage(string &allHtml) //C++11 正则表达式提取图片url{smatch mat;regex pattern("src=\&;(.*?\.jpg)\&;");string::const_iterator start = allHtml.begin();string::const_iterator end = allHtml.end();while (regex_search(start, end, mat, pattern)){string msg(mat[1].first, mat[1].second);photoUrl.push_back(msg);start = mat[0].second;}}void regexGetcom(string &allHtml) //提取网页中的的url{smatch mat;//regex pattern("href=\&;(.*?\.html)\&;");regex pattern("href=\&;([^\s'\&;]+)\&;");string::const_iterator start = allHtml.begin();string::const_iterator end = allHtml.end();while (regex_search(start, end, mat, pattern)){string msg(mat[1].first, mat[1].second);comUrl.push_back(msg);start = mat[0].second;}}void preConnect() //socket进行网络连接{WSADATA wd;WSAStartup(MAKEWORD(2, 2), &wd);sock = socket(AF_INET, SOCK_STREAM, 0);if (sock == INVALID_SOCKET){cout << "建立socket失败！ 错误码： " << WSAGetLastError() << endl;return;}sockaddr_in sa = { AF_INET };int n = bind(sock, (sockaddr*)&sa, sizeof(sa));if (n == SOCKET_ERROR){cout << "bind函数失败！ 错误码： " << WSAGetLastError() << endl;return;}struct hostent *p = gethostbyname(host);if (p == NULL){cout << "主机无法解析出ip! 错误吗： " << WSAGetLastError() << endl;return;}sa.sin_port = htons(80);memcpy(&sa.sin_addr, p->h_addr, 4);// with some problems ???//sa.sin_addr.S_un.S_addr = inet_addr(*(p->h_addr_list));//cout << *(p->h_addr_list) << endl;n = connect(sock, (sockaddr*)&sa, sizeof(sa));if (n == SOCKET_ERROR){cout << "connect函数失败！ 错误码： " << WSAGetLastError() << endl;return;}//像服务器发送GET请求，下载图片string reqInfo = "GET " +(string)othPath+ " HTTP/1.1\r\nHost: " + (string)host + "\r\nConnection:Close\r\n\r\n";if (SOCKET_ERROR == send(sock, reqInfo.c_str(), reqInfo.size(), 0)){cout << "send error! 错误码： " << WSAGetLastError() << endl;closesocket(sock);return;}//PutImagtoSet();}void OutIamge(string imageUrl) //将图片命名，保存在目录下{int n;char temp[800];strcpy(temp, imageUrl.c_str());analyUrl(temp);preConnect();string photoname;photoname.resize(imageUrl.size());int k = 0;for (int i = 0; i<imageUrl.length(); i++){char ch = imageUrl[i];if (ch != '\\'&&ch != '/'&&ch != ':'&&ch != '*'&&ch != '?'&&ch != '"'&&ch != '<'&&ch != '>'&&ch != '|')photoname[k++] = ch;}photoname = "./img/"+photoname.substr(0, k) + ".jpg";fstream file;file.open(photoname, ios::out | ios::binary);char buf[1024];memset(buf, 0, sizeof(buf));n = recv(sock, buf, sizeof(buf)-1, 0);char *cpos = strstr(buf, "\r\n\r\n");//allHtml = "";//allHtml += string(cpos);file.write(cpos + strlen("\r\n\r\n"), n – (cpos – buf) – strlen("\r\n\r\n"));while ((n = recv(sock, buf, sizeof(buf)-1, 0)) > 0){file.write(buf, n);//buf[n] = '\0';//allHtml += string(buf);}//file.write(allHtml.c_str(), allHtml.length());file.close();//closesocket(sock);}void PutImagtoSet() //解析整个html代码{int n;//preConnect();char buf[1024];while ((n = recv(sock, buf, sizeof(buf)-1, 0)) > 0){buf[n] = '\0';allHtml += string(buf);}regexGetimage(allHtml);regexGetcom(allHtml);}void bfs(string beginUrl) //宽度优先搜索，像爬虫一样遍历网页{queue<string> q;q.push(beginUrl);while (!q.empty()){string cur = q.front();mp[cur]++;q.pop();char tmp[800];strcpy(tmp, cur.c_str());analyUrl(tmp);preConnect();PutImagtoSet();vector<string>::iterator ita = photoUrl.begin();for (ita; ita != photoUrl.end(); ++ita){OutIamge(*ita);}photoUrl.clear();vector <string>::iterator it = comUrl.begin();for (it; it != comUrl.end(); ++it){if (mp[*it]==0)q.push(*it);}comUrl.clear();}}int main(){CreateDirectoryA("./img", 0); //在工程下创建文件夹string beginUrl= ""; //输入起始网址bfs(beginUrl);return 0;}
效果图：
只知道心痛得滴血，都只为你。
