c++ - cURL 返回上次请求的数据

Question

我在获取(并从中修改)的 HTTP 类时遇到问题 http://www.zedwood.com/article/125/cpp-libcurl-static-class

Http.h

#ifndef HTTP_H
#define HTTP_H

#include <curl/curl.h>
#include <string>
#include <map>

using namespace std;

class Http {

    public:
        Http(){};
        ~Http(){};

        static string get(const string &url);
        static string get(const string &url, string referer);

        static string post(const string &url, map<string, string> params);
        static string post(const string &url, map<string, string> params, string referer);

        static string get_current_url();
        static string get_last_url();

        static void set_proxy(string ip, long port);
        static void clear_proxy();

        static void set_remote_port(long port);

    private:
        static string request(const string &url, string referer, bool post, const string &params);

        static int writer(char *data, size_t size, size_t nmemb, string *buffer);

        static string urlencode(const string &str);
        static string dechex(char dec);
        static string build_param_string(map<string, string> params);

        static string last_url;
        static string current_url;

        static bool use_proxy;
        static string proxy_ip;
        static long proxy_port;

        static double total_to_download;
        static double now_downloaded;

        static long remote_port;

        static string buffer;
};

#endif

Http.cpp

#include "Http.h"

using namespace std;

string Http::last_url;
string Http::current_url;

bool Http::use_proxy;
string Http::proxy_ip;
long Http::proxy_port;

long Http::remote_port;

string Http::get(const string &url){
    return request(url, "", false, "");
}

string Http::get(const string &url, string referer){
    return request(url, referer, false, "");
}

string Http::post(const string &url, map<string, string> params){
    string postdata = build_param_string(params);

    return request(url, "", true, postdata);
}

string Http::post(const string &url, map<string, string> params, string referer){
    string postdata = build_param_string(params);

    return request(url, referer, true, postdata);
}

string Http::get_current_url(){
    return current_url;
}

string Http::get_last_url(){
    return last_url;
}

void Http::set_proxy(string ip, long port){
    use_proxy = true;
    proxy_ip = ip;
    proxy_port = port;
}

void Http::clear_proxy(){
    use_proxy = false;
}

void Http::set_remote_port(long port){
    remote_port = port;
}

string Http::request(const string &url, string referer, bool post, const string &params){
    static string buffer = "";
    static char error_buffer[CURL_ERROR_SIZE];
    error_buffer[0] = 0;

    CURL *curl;
    CURLcode result;

    curl = curl_easy_init();

    if(curl){
        curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, error_buffer);
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_HEADER, 0);
        curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1);
        curl_easy_setopt(curl, CURLOPT_AUTOREFERER, 1);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, Http::writer);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &(buffer));
        curl_easy_setopt(curl, CURLOPT_COOKIEFILE, ".cookies.cj");
        curl_easy_setopt(curl, CURLOPT_COOKIEJAR, ".cookies.cj");
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST,  2);
        curl_easy_setopt(curl, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)");

        if(post){
            curl_easy_setopt(curl, CURLOPT_POST, 1);
            curl_easy_setopt(curl, CURLOPT_POSTFIELDS, params.c_str());
        }

        if(referer.length()){
            curl_easy_setopt(curl, CURLOPT_REFERER, referer.c_str());
        }

        if(use_proxy){
            curl_easy_setopt(curl, CURLOPT_PROXY, proxy_ip.c_str());

            if(proxy_port){
                curl_easy_setopt(curl, CURLOPT_PROXYPORT, proxy_port);
            }
        }

        if(remote_port){
            curl_easy_setopt(curl, CURLOPT_PORT, remote_port);
        }

        result = curl_easy_perform(curl);

        curl_easy_cleanup(curl);

        if(result == CURLE_OK){
            return buffer;
        }
        else{
            return "error";
        }
    }

    return "error";
}

int Http::writer(char *data, size_t size, size_t nmemb, string *buffer){
    int result = 0;

    if(buffer != NULL){
        buffer->append(data, size * nmemb);
        result = size * nmemb;
    }

    return result;
}

string Http::urlencode(const string &str){
    string encoded = "";

    int max = str.length();

    for(int i = 0; i < max; i++){
        if(
            (48 <= str[i] && str[i] <= 57) ||
            (65 <= str[i] && str[i] <= 90) ||
            (97 <= str[i] && str[i] <= 122) ||
            (str[i] == '~' || str[i] == '!' || str[i] == '*' || str[i] == '(' || str[i] == ')' || str[i] == '\'')
        ){
            encoded.append(&str[i], 1);
        }
        else{
            encoded.append("%");
            encoded.append(dechex(str[i]));
        }
    }

    return encoded;
}

string Http::dechex(char dec){
    char dig1 = (dec&0xF0)>>4;
    char dig2 = (dec&0x0F);
    if ( 0<= dig1 && dig1<= 9) dig1+=48;    //0,48inascii
    if (10<= dig1 && dig1<=15) dig1+=97-10; //a,97inascii
    if ( 0<= dig2 && dig2<= 9) dig2+=48;
    if (10<= dig2 && dig2<=15) dig2+=97-10;

    string r;
    r.append( &dig1, 1);
    r.append( &dig2, 1);
    return r;
}

string Http::build_param_string(map<string, string> params){
    string param_string = "";

    for(map<string, string>::iterator it = params.begin(); it != params.end(); it++){
        param_string += it->first + "=" + urlencode(it->second) + "&";
    }

    param_string = param_string.substr(0, param_string.length() - 1);

    return param_string;
}

如果我发出多个请求，请求函数(.get(); 或 .post();)返回的响应将附加到所有先前请求的返回数据上。

我觉得这很简单，但我错过了，但在过去几天谷歌搜索后我无法弄清楚。

谢谢。

Answer 1

如果在同一行初始化缓冲区:

string Http::request(const string &url, string referer, bool post, const string &params){
    static string buffer = "";

由于 static 修饰符，该初始化只会在您第一次运行该函数时发生。并且因为写函数只是将数据追加到缓冲区...

您需要将其分成两行以重置每次运行的缓冲区:

static string buffer;
buffer.clear();