C++ 使用 curl 进行 http 请求（GET、POST、Download）的封装

修改自网路

CommonTools.h

/*
 * CommonTools.h
 *
 *  Created on: 2018年8月2日
 *      Author: didi
 */
#include <iostream>
#include <curl/curl.h>
#include "zlib.h"
#include <vector>
#include <string>
#include <unistd.h>
#include <memory.h>
#include <json/json.h>
#include <sstream>
using namespace std;

class CommonTools{
    public:
        CommonTools();
        ~CommonTools();
    public:
                static size_t receive_data(void *contents, size_t size, size_t nmemb, void *stream);
        // HTTP 下载文件的回掉函数
        static size_t writedata2file(void *ptr, size_t size, size_t nmemb, FILE *stream);
        // 文件下载接口
        static int download_file(const char* url, const char outfilename[FILENAME_MAX]);
        // http get 请求
        static CURLcode HttpGet(const std::string & strUrl, std::string & strResponse,int nTimeout);
        // htpp post 请求
        static CURLcode HttpPost(const std::string & strUrl, std::string szJson,std::string & strResponse,int nTimeout);
}

CommonTools.cpp

#include "CommonTools.h"
using namespace std;

size_t CommonTools::receive_data(void *contents, size_t size, size_t nmemb, void *stream){
    string *str = (string*)stream;
    (*str).append((char*)contents, size*nmemb);
    return size * nmemb;
}

size_t CommonTools::writedata2file(void *ptr, size_t size, size_t nmemb, FILE *stream) {
    size_t written = fwrite(ptr, size, nmemb, stream);
    return written;
}

int CommonTools::download_file(const char* url, const char outfilename[FILENAME_MAX]){
    CURL *curl;
    FILE *fp;
    CURLcode res;
    /*   调用curl_global_init()初始化libcurl  */
    res = curl_global_init(CURL_GLOBAL_ALL);
    if (CURLE_OK != res)
    {
        printf("init libcurl failed.");
        curl_global_cleanup();
        return -1;
    }
    /*  调用curl_easy_init()函数得到 easy interface型指针  */
    curl = curl_easy_init();
    if (curl) {
        fp = fopen(outfilename,"wb");

        /*  调用curl_easy_setopt()设置传输选项 */
        res = curl_easy_setopt(curl, CURLOPT_URL, url);
        if (res != CURLE_OK)
        {
            fclose(fp);
            curl_easy_cleanup(curl);
            return -1;
        }
        /*  根据curl_easy_setopt()设置的传输选项，实现回调函数以完成用户特定任务  */
        res = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, CommonTools::writedata2file);
        if (res != CURLE_OK){
            fclose(fp);
            curl_easy_cleanup(curl);
            return -1;
        }
        /*  根据curl_easy_setopt()设置的传输选项，实现回调函数以完成用户特定任务  */
        res = curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
        if (res != CURLE_OK)
        {
            fclose(fp);
            curl_easy_cleanup(curl);
            return -1;
        }

        res = curl_easy_perform(curl);
        // 调用curl_easy_perform()函数完成传输任务
        fclose(fp);
        /* Check for errors */
        if(res != CURLE_OK){
            fprintf(stderr, "curl_easy_perform() failed: %s\n",curl_easy_strerror(res));
            curl_easy_cleanup(curl);
            return -1;
        }

        /* always cleanup */
        curl_easy_cleanup(curl);
        // 调用curl_easy_cleanup()释放内存

    }
    curl_global_cleanup();
    return 0;
}

CURLcode CommonTools::HttpGet(const std::string & strUrl, std::string & strResponse,int nTimeout){
    CURLcode res;
    CURL* pCURL = curl_easy_init();

    if (pCURL == NULL) {
        return CURLE_FAILED_INIT;
    }

    curl_easy_setopt(pCURL, CURLOPT_URL, strUrl.c_str());
    //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
    curl_easy_setopt(pCURL, CURLOPT_NOSIGNAL, 1L);
    curl_easy_setopt(pCURL, CURLOPT_TIMEOUT, nTimeout);
    curl_easy_setopt(pCURL, CURLOPT_NOPROGRESS, 1L);
    curl_easy_setopt(pCURL, CURLOPT_WRITEFUNCTION, CommonTools::receive_data);
    curl_easy_setopt(pCURL, CURLOPT_WRITEDATA, (void*)&strResponse);
    res = curl_easy_perform(pCURL);
    curl_easy_cleanup(pCURL);
    return res;
}

CURLcode CommonTools::HttpPost(const std::string & strUrl, std::string szJson,std::string & strResponse,int nTimeout){
    CURLcode res;
    char szJsonData[];
    memset(szJsonData, 0, sizeof(szJsonData));
    strcpy(szJsonData, szJson.c_str());
    CURL* pCURL = curl_easy_init();
    struct curl_slist* headers = NULL;
    if (pCURL == NULL) {
        return CURLE_FAILED_INIT;
    }

    CURLcode ret;
    ret = curl_easy_setopt(pCURL, CURLOPT_URL, strUrl.c_str());
//    std::cout << ret << std::endl;

    ret = curl_easy_setopt(pCURL, CURLOPT_POST, 1L);
    headers = curl_slist_append(headers,"content-type:application/json");

    ret = curl_easy_setopt(pCURL, CURLOPT_HTTPHEADER, headers);

    ret = curl_easy_setopt(pCURL, CURLOPT_POSTFIELDS, szJsonData);
    //curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
    ret = curl_easy_setopt(pCURL, CURLOPT_TIMEOUT, nTimeout);

    ret = curl_easy_setopt(pCURL, CURLOPT_WRITEFUNCTION, CommonTools::receive_data);

    ret = curl_easy_setopt(pCURL, CURLOPT_WRITEDATA, (void*)&strResponse);

    res = curl_easy_perform(pCURL);
    curl_easy_cleanup(pCURL);
    return res;
}

使用方法

Main.cpp

// get 请求
string strURL = "http://www.baidu.com";
string strResponse;
CURLcode nRes = CommonTools::HttpGet(strURL, strResponse,);
size_t nSrcLength = strResponse.length();

//下载文件
string strURL = "http://www.baidu.com/aaa.dat";
char local_file[] = {};
sprintf(local_file,"./pb_%d_%s.dat",,"aaaa");
int iDownlaod_Success = CommonTools::download_file(url.c_str(),local_file);
if(iDownlaod_Success<){
    char download_failure_info[] ={};
    sprintf(download_failure_info,"download file :%s ,failure,url:",local_file,url);
    FATAL(download_failure_info);
}