使用libcurl发送HTTP请求的一个简单示例代码

代码简单解释

设置header

首先要声明header的结构体变量，然后设置对应header值，最后将其设置到curl结构体中

//声明
CURL *curl;
struct curl_slist *headers = NULL;

//赋值header值
headers = curl_slist_append(headers, "Host: 0xz.sz.qcloud.com");
headers = curl_slist_append(headers, "yousa3: zym");

//设置header
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

指定url

//声明url
string url = "http://10.54.69.29:80/test/usr/loveqiqian";

//指定url
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());

//发送http请求
res = curl_easy_perform(curl);

设置HTTP请求的body

这里发送的请求是POST请求，通过如下代码设置的是POST请求
curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "POST");

如果没有指定contenttype，那么contenttype默认是post的标准表单格式，application/x-www-form-urlencoded

设置body是如下代码：

//先用char[] 准备好要发送的body字符串
char hello[12] = "a=hello";

//设置body长度以及内容
curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, strlen(hello));
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, hello);

//然后就可以使用easy_perform接口发送了。

获取响应响应码

res获取到的就是HTTP响应码

res = curl_easy_perform(curl);

获取响应header以及响应body

//声明
string header;
string result;

//设置
curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, &write_data);
curl_easy_setopt(curl, CURLOPT_HEADERDATA, &header);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &write_data);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, &result);

//write_data函数是这样
size_t write_data(void *buffer, size_t size, size_t nmemb, void *userp){
    char *d = (char*)buffer;
    string *b = (string*)(userp);
    int result = 0;
    if (b != NULL){
        b->append(d, size*nmemb);
        result = size*nmemb;
    }
    return result;
}

PS：HEAD请求的响应是没有body的，需要额外设置一行

curl_easy_setopt(curl, CURLOPT_NOBODY, 1);

代码

#include 
#include 
#include 
#include 

using namespace std;

size_t write_data(void *buffer, size_t size, size_t nmemb, void *userp);

int main() {
    cout<<"hello world" << endl;

    CURL *curl;
    CURLcode res;
    curl = curl_easy_init();
    string url = "http://10.54.69.29:80/test/usr/loveqiqian";
    string header;
    string result;
    struct curl_slist *headers = NULL;
    char hello[12] = "a=hello";



    headers = curl_slist_append(headers, "Host: 0xz.sz.qcloud.com");
    headers = curl_slist_append(headers, "yousa3: zym");

    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

    curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "POST");
    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());

    curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, strlen(hello));
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, hello);

    curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, &write_data);
    curl_easy_setopt(curl, CURLOPT_HEADERDATA, &header);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &write_data);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &result);
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, 10);
    res = curl_easy_perform(curl);

    cout << header << endl << endl;
    cout << result << endl;
    cout << res << endl;
    curl_easy_cleanup(curl);

    return 0;

}

size_t write_data(void *buffer, size_t size, size_t nmemb, void *userp){
    char *d = (char*)buffer;
    string *b = (string*)(userp);
    int result = 0;
    if (b != NULL){
        b->append(d, size*nmemb);
        result = size*nmemb;
    }
    return result;
}