[C++]Http Get與Post函式(Curl)

序言

此篇記錄我使用Curl函式庫來達成Http的Get與Post方法。

開發環境

• VS2008
• curl-7.21.4
  

編譯Curl函式庫

1. 下載curl-7.21.4.zip，解壓縮後可以得到[curl-7.21.4]目錄
2. 進入[curl-7.21.4]目錄會找到[vc6curl.dsw]專案，以Visual Studio 2008開啟
3. 建置專案
   
4. 建置成功後會在[curl-7.21.4\lib\DLL-Debug]目錄下看到編譯完成的libcurld.dll、libcurld_imp.lib
   

設定開發專案

1. 將上一步產生的[libcurld.dll]複製到[C:\WINDOWS\system32]
2. 於開發用的C++專案設定屬性：展開[組態屬性→C/C++→一般]，修改[其他Include目錄]，指到[curl-7.21.4]目錄中的include資料夾
   
3. 展開[組態屬性→連結器→一般]，修改[其他程式庫目錄]，指到[curl-7.21.4\lib\DLL-Debug]目錄
   
4. 展開[組態屬性→連結器→輸入]，修改[其他相依性]，，增加[libcurld_imp.lib]
   
   

Http連線函式庫

1. HttpIO.h
   

   #pragma once
   #include 
   using namespace std;
   namespace commonio {
    class HttpIO
    {
    public:
     /**
     **post方法
     **isRedirect:是否依head redirect
     **param:傳參數，如val1=123&val2=abc
     **timeout:等待回應逾期時間(秒)，為不限制
     **/
     static string doPost(string URL,bool isRedirect,string param="",long timeout=0);
     /**
     **get方法
     **isRedirect:是否依head redirect
     **timeout:等待回應逾期時間(秒)，為不限制
     **/
     static string doGet(string URL,bool isRedirect,long timeout=0);
    };
   };

2. HttpIO.cpp
   

   #include "StdAfx.h"
   #include 
   //#include 
   #include 
   #include "HttpIO.h"
   
   using namespace std;
   using namespace commonio;
   
   
   // This is the writer call back function used by curl
   size_t writer (char *data, size_t size, size_t nmemb, std::string *buffer)
   {
       size_t result = 0;
       if (buffer != NULL)
       {
           buffer->append (data, size * nmemb);
           result = size * nmemb;
       }
       return result;
   }    
   
   
   
   string HttpIO::doPost(string URL,bool isRedirect,string param,long timeout)
   {
       CURL *curl;
       CURLcode cc;
       string bufferdata;
    string error;
    //string user_agent("Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
    if ((curl = curl_easy_init()) == NULL)
           exit(1);
    curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, error);
       curl_easy_setopt(curl, CURLOPT_URL, URL.c_str()); // URL used for posting
    //curl_easy_setopt(curl, CURLOPT_USERAGENT, user_agent);
    
   
    if(isRedirect) curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1); //Redirect
    if(timeout>0) curl_easy_setopt(curl, CURLOPT_TIMEOUT, timeout); //times out after second
       curl_easy_setopt(curl, CURLOPT_POST, 1);//Tell libcurl to use POST
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, param.c_str());
       curl_easy_setopt (curl, CURLOPT_WRITEFUNCTION,   writer);
       curl_easy_setopt (curl, CURLOPT_WRITEDATA,&bufferdata);
       //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1);  //Debug
       //cc=curl_easy_setopt(curl, CURLOPT_HEADER, 1);    //Debug
    cc = curl_easy_perform(curl);
    
       curl_easy_cleanup(curl);
       if(cc == CURLE_OK)
           {
               string data;
               data=bufferdata;
               bufferdata="";
      return data;
           }      
           else
           {
               //cout << "Error: [" << cc << "] - "<< error;
      string data("");
      return data;
           }
   }
   
   string HttpIO::doGet(string URL,bool isRedirect,long timeout)
   {
       CURL *curl;
       CURLcode cc;
   
       string bufferdata;
    string error;
       if ((curl = curl_easy_init()) == NULL)
           exit(1);
    curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, error);
       curl_easy_setopt(curl, CURLOPT_URL, URL.c_str()); // URL used for posting
    if(isRedirect) curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1); //Redirect
    if(timeout>0) curl_easy_setopt(curl, CURLOPT_TIMEOUT, timeout); //times out after second
       curl_easy_setopt (curl, CURLOPT_WRITEFUNCTION,   writer);
       curl_easy_setopt (curl, CURLOPT_WRITEDATA,&bufferdata);
    //cc=curl_easy_setopt(curl, CURLOPT_HEADER, 1);    //Debug
       cc = curl_easy_perform(curl);
       curl_easy_cleanup(curl);
       if(cc == CURLE_OK)
           {
               string data;
               data=bufferdata;
               bufferdata="";
      return data;
           }      
           else
           {
               //cout << "Error: [" << cc << "] - "<< error;
      string data("");
      return data;
           }
   }

3. 額外函式
• CommonFunc.h
  

  #pragma once
  using namespace std;
  namespace commonio {
   class CommonFunc
   {
   public:
    static void str_split(const string& str,
          vector& tokens,
          const string& delimiters = " ");
    static vector> paramToArray(string param);
   };
  };

• CommonFunc.cpp
  

  #include "stdafx.h"
  
  #include 
  #include 
  #include "CommonFunc.h"
  using namespace std;
  using namespace commonio;
  void CommonFunc::str_split(const string& str,
                        vector& tokens,
                        const string& delimiters){
      // Skip delimiters at beginning.
      string::size_type lastPos = str.find_first_not_of(delimiters, 0);
      // Find first "non-delimiter".
      string::size_type pos     = str.find_first_of(delimiters, lastPos);
  
      while (string::npos != pos || string::npos != lastPos)
      {
          // Found a token, add it to the vector.
          tokens.push_back(str.substr(lastPos, pos - lastPos));
          // Skip delimiters.  Note the "not_of"
          lastPos = str.find_first_not_of(delimiters, pos);
          // Find next "non-delimiter"
          pos = str.find_first_of(delimiters, lastPos);
      }
  }
  
  
  vector> CommonFunc::paramToArray(string param){
     vector>  arr;
     vector p;
     CommonFunc::str_split(param,p,"&");
     if (param.find("&")>-1) {
      vector p2;
      int j = 0;
      for (unsigned int i = 0; i < p.size(); i++) {
       if (p[i].find_first_of("amp;")==0) {
        p2[j - 1]=p2[j - 1] + "&" + p[i].substr(4);
        j--;
       }
       p2.push_back(p[i]);
       j++;
      }
      p=p2;
     }
  
     for (unsigned int i = 0; i < p.size(); i++) {
      vector item;
      CommonFunc::str_split(p[i],item,"=");
      if (item.size() == 2) {
       arr.push_back(item);
      }
     }
     return arr;
    }

使用範例程式

#include "stdafx.h"
#include 
#include 
#include "HttpIO.h"
using namespace std;
using namespace commonio;

int main(int argc, _TCHAR* argv[])
{
 string data=HttpIO::doGet("http://www.google.com",false);
 cout << '\t' << data << endl;
    return 0;
}