C++ REST SDK Casablanca Client.request

问题:

I want to write a little c++ program that sends a request to a server an get some data. I found the C++ Rest-SDK and decided to use it. I searched on different websites for code-examples but many of them doesn't work an shows syntax errors. What i got now is that code but the client.request method is skipped. The program never jumps in. Hope someone can realise the problem and maybe explain what i have to change.

#include <Windows.h>
#include <iostream>
#include <sstream>
#include <string>
#include "cpprest/containerstream.h"
#include "cpprest/filestream.h"
#include "cpprest/http_client.h"
#include "cpprest/json.h"
#include "cpprest/producerconsumerstream.h"
#include "cpprest/http_client.h"
#include <string.h>
#include <conio.h>

using namespace std;
using namespace web;
using namespace web::json;
using namespace web::http;
using namespace web::http::client;
using namespace utility;
using namespace utility::conversions;


int main() {

  http_client client(L"http://httpbin.org/ip");

  client.request(methods::GET).then([](http_response response)
  { 
    if(response.status_code() == status_codes::OK)
    {
      auto body = response.extract_string().get();    
      std::wcout << body;
      getch();
    }
  });


  return 0;
}

回答1:

It is possible that the main thread is terminated before the "request" task completed, so you cannot see any console outputs. I suggest you to call the task "wait()" function after ".then", like in the answer on their site

回答2:

Your program runs off the end of main and terminates. You need to add wait after the then call:

client.request(methods::GET).then([](http_response response)
{ 
    // ...
}).wait();

回答3:

this code is working :

// ConsoleApplication1.cpp : Defines the entry point for the console application.
//
#include "StdAfx.h"
#include <cpprest/http_client.h>
#include <cpprest/filestream.h>

using namespace utility;                    // Common utilities like string conversions
using namespace web;                        // Common features like URIs.
using namespace web::http;                  // Common HTTP functionality
using namespace web::http::client;          // HTTP client features
using namespace concurrency::streams;       // Asynchronous streams



int main(int argc, char* argv[])
{





    // Make the request and asynchronously process the response. 


    http_client client(L"http://localhost:8082/TPJAXRS/Test/test");

  client.request(methods::GET).then([](http_response response)
  { 
    if(response.status_code() == status_codes::OK)
    {
      auto body = response.extract_string().get();    
      std::wcout << body<< std::endl;



    }});
    std::cout << "Hello world!" << std::endl;


system("PAUSE");
        return 0;


}

回答4:

#include <cpprest/http_client.h>
#include <cpprest/filestream.h>
#include <cpprest/http_listener.h>              // HTTP server
#include <cpprest/json.h>                       // JSON library
#include <cpprest/uri.h>                        // URI library
#include <cpprest/ws_client.h>                  // WebSocket client
#include <cpprest/containerstream.h>            // Async streams backed by                    STL containers
#include <cpprest/interopstream.h>              // Bridges for integrating  Async streams with STL and WinRT streams
#include <cpprest/rawptrstream.h>               // Async streams backed by raw pointer to memory
#include <cpprest/producerconsumerstream.h>     // Async streams for producer consumer scenarios
using namespace utility;                    // Common utilities like string conversions
using namespace web;                        // Common features like URIs.
using namespace web::http;                  // Common HTTP functionality
using namespace web::http::client;          // HTTP client features
using namespace concurrency::streams;       // Asynchronous streams
using namespace web::http::experimental::listener;          // HTTP server
using namespace web::experimental::web_sockets::client;     // WebSockets client
using namespace web::json;                                  // JSON library
int main(int argc, char* argv[])
{
 auto fileStream = std::make_shared<ostream>();

// Open stream to output file.
    pplx::task<void> requestTask =   fstream::open_ostream(U("results.html")).then([=](ostream outFile)
{
    *fileStream = outFile;

    // Create http_client to send the request.
    http_client client(U("http://www.bing.com/"));

    // Build request URI and start the request.
    uri_builder builder(U("/search"));
    builder.append_query(U("q"), U("cpprestsdk github"));
    return client.request(methods::GET, builder.to_string());
})

    // Handle response headers arriving.
    .then([=](http_response response)
{
    printf("Received response status code:%u\n", response.status_code());

    // Write response body into the file.
    return response.body().read_to_end(fileStream->streambuf());
})

    // Close the file stream.
    .then([=](size_t)
{
    return fileStream->close();
});

// Wait for all the outstanding I/O to complete and handle any exceptions
try
{
    requestTask.wait();
}
catch (const std::exception &e)
{
    printf("Error exception:%s\n", e.what());
}

return 0;
}

This is for setting in HTTP request

link for HTTP tutorial for further information go through this tutorial