如何使用libmicrohttpd库的C++采集百度图片库

```cpp
#include
#include
#include
#include
#include
using namespace std;
// 获取代理服务器函数
vector get_proxy() {
vector proxies;
// 使用CURL获取服务器列表
CURL *curl;
CURLcode res;
string url = "https://www.duoip.cn/get_proxy";
curl = curl_easy_init();
if(curl) {
string proxy_str;
res = curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
if(res == CURLE_OK) {
res = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, NULL);
if(res == CURLE_OK) {
res = curl_easy_perform(curl, &proxy_str);
if(res == CURLE_OK) {
// 将获取到的服务器添加到vector中
stringstream ss(proxy_str);
string item;
while(getline(ss, item, ',')) {
proxies.push_back(item);
}
}
}
}
curl_easy_cleanup(curl);
}
return proxies;
}
int main() {
vector proxies = get_proxy();
if(!proxies.empty()) {
// 使用第一个服务器进行爬取
string proxy = proxies[0];
cout << "Using proxy: " << proxy << endl;
// 创建一个microhttpd服务器
struct MHD_Daemon *daemon;
daemon = MHD_start_daemon(MHD_USE_THREAD_PER_CONNECTION, 8080, NULL, NULL, ℑ_handler, NULL);
if(daemon) {
// 等待服务器关闭
MHD_wait_forever(daemon);
}
}
return 0;
}
// 处理图像请求的函数
int image_handler(void *cls, struct MHD_Connection *connection,
const char *url, const char *method, const char *version,
const char *upload_data, size_t *upload_data_size) {
// 检查URL，确保是/image请求
if(strcmp(url, "/image") == 0) {
// 使用CURL下载图像
CURL *curl;
CURLcode res;
string image_url = "https://www.baidu.com/img/bd_logo1.png";
curl = curl_easy_init();
if(curl) {
res = curl_easy_setopt(curl, CURLOPT_URL, image_url.c_str());
if(res == CURLE_OK) {
res = curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, NULL);
if(res == CURLE_OK) {
res = curl_easy_perform(curl, NULL);
if(res == CURLE_OK) {
// 将图像数据发送到客户端
const char *header = "Content-Type: image/png\r\n\r\n";
MHD_send_response(connection, MHD_HTTP_OK, header, strlen(header));
res = curl_easy_getinfo(curl, CURLINFO_RESPONSE_SIZE, &(size_t) 1);
if(res == CURLE_OK) {
MHD_send_response_chunk(connection, image_url.c_str(), image_url.size());
}
}
}
}
curl_easy_cleanup(curl);
}
return MHD_YES;
}
return MHD_NO;
}
```