如何使用 Boost::Asio 访问 Web 服务?
Posted
技术标签:
【中文标题】如何使用 Boost::Asio 访问 Web 服务?【英文标题】:How to access web service using Boost::Asio? 【发布时间】:2017-06-06 09:59:02 【问题描述】:我想知道是否有可能使用 boost asio 库访问网络服务。
我尝试了从 boost asio 文档中获得的以下代码(在 ios,C++11 中)。 但它抛出了以下内容。
try
boost::asio::io_service io_service;
std::string address = "http://www.thomas-bayer.com/axis2/services/BLZService/";
// Get a list of endpoints corresponding to the server name.
tcp::resolver resolver(io_service);
tcp::resolver::query query(address,boost::asio::ip::resolver_query_base::numeric_service);
tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
endpoint_iterator->host_name() = "www.thomas-bayer.com/axis2/services/BLZService/";
std::cout<<"Print Query --"<<std::endl;
// Try each endpoint until we successfully establish a connection.
tcp::socket socket(io_service);
boost::asio::connect(socket, endpoint_iterator);
// Form the request. We specify the "Connection: close" header so that the
// server will close the socket after transmitting the response. This will
// allow us to treat all data up until the EOF as the content.
boost::asio::streambuf request;
std::ostream request_stream(&request);
request_stream << "POST: HTTP/1.0\r\n";
request_stream << "Host: " << address << "\r\n";
request_stream << "Accept: */*\r\n";
request_stream << "Connection: close\r\n\r\n";
// Send the request.
boost::asio::write(socket, request);
// Read the response status line. The response streambuf will automatically
// grow to accommodate the entire line. The growth may be limited by passing
// a maximum size to the streambuf constructor.
boost::asio::streambuf response;
boost::asio::read_until(socket, response, "\r\n");
// Check that response is OK.
std::istream response_stream(&response);
std::string http_version;
response_stream >> http_version;
unsigned int status_code;
response_stream >> status_code;
std::string status_message;
std::getline(response_stream, status_message);
if (!response_stream || http_version.substr(0, 5) != "HTTP/")
std::cout << "Invalid response\n";
return;
if (status_code != 200)
std::cout << "Response returned with status code " << status_code << "\n";
return;
// Read the response headers, which are terminated by a blank line.
boost::asio::read_until(socket, response, "\r\n\r\n");
// Process the response headers.
std::string header;
while (std::getline(response_stream, header) && header != "\r")
std::cout << header << "\n";
std::cout << "\n";
// Write whatever content we already have to output.
if (response.size() > 0)
std::cout << &response;
// Read until EOF, writing data to output as we go.
boost::system::error_code error;
while (boost::asio::read(socket, response,
boost::asio::transfer_at_least(1), error))
std::cout << &response;
if (error != boost::asio::error::eof)
throw boost::system::system_error(error);
catch (std::exception& e)
std::cout << "Exception: " << e.what() << "\n";
例外:连接:无法分配请求的地址
或者
异常:解决:找不到主机(权威)
代码有什么问题?还是我做错了?
谢谢
【问题讨论】:
我认为问题与访问Web服务无关,相反,我认为上面的代码无法解析主机名。也许这两个链接可以帮助你。 Boost not working over network 和这个boost asio: “host not found (authorative)” 解析器使用主机名而不是 URL。使用thomas-bayer.com
作为解析器。
tcp::resolver::query query(address,boost::asio::ip::resolver_query_base::numeric_service);
解决主机未找到错误但产生无法分配请求的地址。基本上我得到上述错误之一。我将尝试使用您提供的第一个链接并回来。谢谢
嗨@JohnTracid 我已尝试将网址设置为如下tcp::resolver::query query("thomas-bayer.com", boost::asio::ip::resolver_query_base::numeric_service);
但我无法分配请求地址错误。谢谢
【参考方案1】:
名称解析失败,因为您混淆了什么是请求、URL、协议、主机名和 IP 地址。
在FQDN 上提出请求。除非您知道,否则您需要提供服务。在这种情况下,服务遵循协议¹,`http:// 通常在端口 80 上提供:
std::string const address = "www.thomas-bayer.com";
tcp::resolver::query query(address, "80", boost::asio::ip::resolver_query_base::numeric_service);
请注意,在大多数系统上,您可以等效地使用:
std::string const address = "www.thomas-bayer.com";
tcp::resolver::query query(address, "http");
看到http://
和www.thomas-bayer.com
部分去了哪里?
现在/axis2/services/BLZService/
是查询路径,就像您在 GET 请求中所写的那样:
request_stream << "GET /axis2/services/BLZService/ HTTP/1.1\r\n";
注意事项:
-
POST 不是标头(所以没有冒号!)它是 HTTP“动词”(GET、POST、DELETE、PUT...)
“主机”标头是主机名:
request_stream << "Host: " << address << "\r\n";
是正确的 iff address
确实是主机的逻辑名称
这样设置主机名:
endpoint_iterator->host_name() = "www.thomas-bayer.com/axis2/services/BLZService/";
是我以前从未见过的东西,我不确定它应该实现什么。也许只是错了?
¹ 按照惯例,可能是其他
修复
#include <boost/asio.hpp>
#include <iostream>
using boost::asio::ip::tcp;
void test() try
boost::asio::io_service io_service;
std::string const address = "www.thomas-bayer.com";
// Get a list of endpoints corresponding to the server name.
tcp::resolver resolver(io_service);
tcp::resolver::query query(address, "80", boost::asio::ip::resolver_query_base::numeric_service);
tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
std::cout << "Print Query --" << std::endl;
// Try each endpoint until we successfully establish a connection.
tcp::socket socket(io_service);
boost::asio::connect(socket, endpoint_iterator);
// Form the request. We specify the "Connection: close" header so that the
// server will close the socket after transmitting the response. This will
// allow us to treat all data up until the EOF as the content.
boost::asio::streambuf request;
std::ostream request_stream(&request);
request_stream << "GET /axis2/services/BLZService HTTP/1.0\r\n";
request_stream << "Host: " << address << "\r\n";
request_stream << "Accept: */*\r\n";
request_stream << "Connection: close\r\n\r\n";
// Send the request.
boost::asio::write(socket, request);
// Read the response status line. The response streambuf will automatically
// grow to accommodate the entire line. The growth may be limited by
// passing a maximum size to the streambuf constructor.
boost::asio::streambuf response;
boost::asio::read_until(socket, response, "\r\n");
// Check that response is OK.
std::istream response_stream(&response);
std::string http_version, status_message;
unsigned int status_code;
std::getline(response_stream >> http_version >> status_code, status_message);
if (!response_stream || http_version.substr(0, 5) != "HTTP/")
std::cout << "Invalid response\n";
return;
if (status_code != 200)
std::cout << "Response returned with status code " << status_code << "\n";
return;
// Read the response headers, which are terminated by a blank line.
boost::asio::read_until(socket, response, "\r\n\r\n");
// Process the response headers.
std::string header;
while (std::getline(response_stream, header) && header != "\r")
std::cout << header << "\n";
std::cout << "\n";
// Write whatever content we already have to output.
if (response.size() > 0)
std::cout << &response;
// Read until EOF, writing data to output as we go.
boost::system::error_code error;
while (boost::asio::read(socket, response, boost::asio::transfer_at_least(1), error))
std::cout << &response;
if (error != boost::asio::error::eof)
throw boost::system::system_error(error);
catch (std::exception &e)
std::cout << "Exception: " << e.what() << "\n";
int main() test();
【讨论】:
您好其实我尝试将我的请求发布到网络服务,但是为什么你改为 GET 呢? @Kid 为什么不呢?我只是忘记改回来了。我倾向于在发布答案之前测试我的代码,并且我不会向我一无所知的服务器发送 POST 请求。 哦,好的。它返回方法`GET -- 响应返回状态码500`和POST -- Exception: read_until: End of file
。但我还没有添加实际的 xml 请求。可能这会导致这些错误。我目前正在研究它。谢谢以上是关于如何使用 Boost::Asio 访问 Web 服务?的主要内容,如果未能解决你的问题,请参考以下文章
多线程应用程序上的 boost::asio::ssl 访问冲突
Boost Asio 访问 asio::ip::address 底层数据和字节顺序