使用Boost Asio获取网页 [英] Using boost asio to get web page
问题描述
我正在尝试构建一个程序，该程序将使用股票行情自动收录器，对它进行谷歌搜索，然后输出数据(当前价格，最高价，最低价，涨跌幅等).我正在尝试使用boost asio，它没有从服务器返回任何数据.
I'm trying to build a program that would take in a stock ticker, run a google search for it, and output data (current price, high, low, percent change, etc.). I am trying to use boost asio and it is not returning any data from the server.
#include "stdafx.h"
#include <iostream>
#include <istream>
#include <ostream>
#include <string>
#include <boost/asio.hpp>
std::string getStockPage(std::string ticker) {
boost::asio::ip::tcp::iostream stream;
stream.connect("www.google.com", "http");
std::cout << "connected\n";
stream << "GET /search?q=" << ticker << " HTTP/1.1\r\n";
stream << "Host: www.google.com\r\n";
stream << "Cache-Control: no-cache\r\n";
//stream << "Content-Type: application/x-www-form-urlencoded\r\n\r\n";
stream << "Connection: close\r\n\r\n";
std::cout << "sent\n";
std::ostringstream os;
//os << stream.rdbuf();
char buffer[100];
os << stream.readsome(buffer, 100);
return std::string(buffer, 100);
}
int main() {
std::cout << getStockPage("$tsla");
std::cout << "done\n";
std::string temp;
std::getline(std::cin, temp);
return 0;
}
我尝试仅读取前100个字符，以查看输出响应时是否遇到问题，但仅输出空字符.我希望它输出整个Google页面"www.google.com/search?q=$tsla"
I tried to read just the first 100 characters to see if it was having issues outputting the response, but it only outputs null characters. I want it to output the entirety of the google page "www.google.com/search?q=$tsla"
任何帮助将不胜感激！
推荐答案
std :: istream :: readsome 只允许始终返回0个字节.然后，好像您收到了NUL字节一样，因为您确实收到了
std::istream::readsome is allowed to just always return 0 bytes. Then, it appears as if you received NUL bytes, because you did
return std::string(buffer, 100);
代替
return std::string(buffer, stream.gcount());
真的，只需使用其他方法
Really, just use the other approach
std::ostringstream os;
os << stream.rdbuf();
return os.str();
这在测试时对我有用.请注意，您可以添加刷新:
This works for me when testing. Note you could add a flush:
stream << "Connection: close\r\n\r\n" << std::flush;
生成的程序
#include <boost/asio.hpp>
#include <iostream>
#include <string>
std::string getStockPage(std::string const& ticker) {
boost::asio::ip::tcp::iostream stream;
stream.connect("www.google.com", "http");
stream << "GET /search?q=" << ticker << " HTTP/1.1\r\n";
stream << "Host: www.google.com\r\n";
stream << "Cache-Control: no-cache\r\n";
// stream << "Content-Type: application/x-www-form-urlencoded\r\n\r\n";
stream << "Connection: close\r\n\r\n" << std::flush;
std::ostringstream os;
os << stream.rdbuf();
return os.str();
}
int main() {
std::cout << getStockPage("$tsla");
}
正在打印
HTTP/1.1 302 Found
Location: http://www.google.nl/search?q=%24tsla&gws_rd=cr&dcr=0&ei=3EMqWrKxCILUwAKv9LqICg
Cache-Control: private
Content-Type: text/html; charset=UTF-8
P3P: CP="This is not a P3P policy! See g.co/p3phelp for more info."
Date: Fri, 08 Dec 2017 07:48:44 GMT
Server: gws
Content-Length: 288
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Set-Cookie: NID=118=MsVZZpoZFEz4mQDqDuuWFRViB8v8yEQju7FPdOw8Rr7ViQ1cJtF6ZeN9u-dSRhGMT4x8F8yDilk9FqsoTkO8IsoQX-YvHXRcCoHcOLk0p4VOTn8AZoldKeh84Ryl0bM0; expires=Sat, 09-Jun-2018 07:48:44 GMT; path=/; domain=.google.com; HttpOnly
Connection: close
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>302 Moved</TITLE></HEAD><BODY>
<H1>302 Moved</H1>
The document has moved
<A HREF="http://www.google.nl/search?q=%24tsla&gws_rd=cr&dcr=0&ei=3EMqWrKxCILUwAKv9LqICg">here</A>.
</BODY></HTML>
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