通过HTTP GET下载网页(socket编程)
基于linux socket，通过了http get方法获得网页信息
遇到问题与解决方法：利用超时方法判断http server发送数据完毕
通过select函数来实现超时。
GET方法的命令形式
GET / HTTP/1.1
包括两个文件HttpConnection.h和HttpConnection.cpp
HttpConnection.h
#ifndef HTTP_CONNECTION_H
#define HTTP_CONNECTION_H
#include <string>
#include <QtCore/QObject>
using std::string;
#define MAX_BUFF_LEN 4096
#define SLEEP_TIME 2
namespace HTTP
{
class HttpConnection
{
public:
HttpConnection(string hostname,int port):hostname(hostname),port(port){}
HttpConnection()
{
hostname="www.163.com";
port = 80;
}
int http_connect();
string get_html(const string) const;
void http_close();
private:
int conn_sock;
string hostname;
int port;
int status_code;
int total_bytes;
int current_bytes;
};
}
#endif
HttpConnection.cpp
#include <unistd.h>
#include <stdlib.h>
#include <iostream>
#include <string>
#include <strings.h>
#include <cstring>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sstream>
#include <errno.h>
#include <sys/select.h>
#include <sys/time.h>
#include "HttpConnection.h"
using namespace std;
int HTTP::HttpConnection::http_connect()
{
struct hostent *hptr;
char ip_dot_num[INET_ADDRSTRLEN];
char **ptr;
struct sockaddr_in servaddr;
if((hptr = gethostbyname(hostname.c_str()))==NULL)
{
#ifdef DEBUG
cout<<"gethostbyname error for host "<<hostname<<endl;
#endif
return -1;
}
if(hptr->h_addrtype!=AF_INET)
{
#ifdef DEBUG
cout<<"not support the address type"<<endl;
#endif
return -1;
}
ptr = hptr->h_addr_list;
inet_ntop(AF_INET,*ptr,ip_dot_num,sizeof(ip_dot_num));
#ifdef DEBUG
cout<<"connect to "<<ip_dot_num<<" ..."<<endl;
#endif
conn_sock = socket(AF_INET,SOCK_STREAM,0);
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(port);
int ret;
if((ret =inet_pton(AF_INET, ip_dot_num, &servaddr.sin_addr))!=1)
{
#ifdef DEBUG
cout<<"inet_pton: invalid input or error "<<ret<<endl;
#endif
return -1;
}
if(::connect(conn_sock,(struct sockaddr *)&servaddr, sizeof(servaddr))!=0)
{
#ifdef DEBUG
cout<<"failed to connect"<<endl;
#endif
return -1;
}
#ifdef DEBUG
cout<<"succeed to connect"<<endl;
#endif
return 0;
}
void HTTP::HttpConnection::http_close()
{
if(close(conn_sock)==0)
{
#ifdef DEBUG
cout<<"succeed to close socket"<<endl;
#endif
}
else
{
#ifdef DEBUG
cout<<"failed to close socket"<<endl;
#endif
}
}
string HTTP::HttpConnection::get_html(string path) const
{
stringstream strm;
strm<<"GET "<<path<<" HTTP/1.1\n";
strm<<"Connection:Keep-Alive\r\n";
strm<<"Cache-Control:no-cache\r\n";
strm<<"\r\n";
char *send_content = (char *)strm.str().c_str();
char receive_buff[MAX_BUFF_LEN];
ssize_t nwritten;
nwritten = write(conn_sock,send_content,strlen(send_content));
string receive_content;
#ifdef DEBUG
cout<<"send request to server"<<endl;
cout<<strm.str()<<endl;
#endif
ssize_t nread;
while(true)
{
fd_set rset;
struct timeval tv;
tv.tv_sec = SLEEP_TIME;
tv.tv_usec = 0;
FD_ZERO(&rset);
FD_SET(conn_sock,&rset);
int ret = select(conn_sock+1,&rset,NULL,NULL,&tv);
if (ret == 0)
break;
nread = read(conn_sock,receive_buff,MAX_BUFF_LEN);
if(nread<0 && errno==EINTR)
{
continue;
}
else if(nread>0)
{
receive_buff[nread]='\0';
receive_content.append(receive_buff);
continue;
}
break;
}
return receive_content;
}
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