API文档

#include <iostream>
#include "curl_install/include/curl/curl.h"
#include <fstream>
#include "Base64.h"
#include <cctype>
#include <iomanip>
#include <sstream>
#include <string>

using namespace std;
// libcurl库下载链接：https://curl.haxx.se/download.html
// 通用iocr的接口url
static string ocr_result;
/**
 * curl发送http请求调用的回调函数，回调函数中对返回的json格式的body进行了解析，解析结果储存在全局的静态变量当中
 * @param 参数定义见libcurl文档
 * @return 返回值定义见libcurl文档
 */
static size_t callback(void *ptr, size_t size, size_t nmemb, void *stream) {
    // 获取到的body存放在ptr中，先将其转换为string格式
    ocr_result = string((char *) ptr, size * nmemb);
    return size * nmemb;
}

string url_encode(const std::string &value) {
    ostringstream escaped;
    escaped.fill('0');
    escaped << hex;
    for (std::string::const_iterator i = value.begin(), n = value.end(); i != n; ++i) {
        std::string::value_type c = (*i);
        // Keep alphanumeric and other accepted characters intact
        if (isalnum(c) || c == '-' || c == '_' || c == '.' || c == '~') {
            escaped << c;
            continue;
        }
        // Any other characters are percent-encoded
        escaped << uppercase;
        escaped << '%' << setw(2) << int((unsigned char) c);
        escaped << nouppercase;
    }

    return escaped.str();
}
// base64.h下载地址
// https://bj.bcebos.com/v1/iocr-movie/Base64.h
int iocr_regenize(const std::string &image_base64, const std::string &access_token, 
    const std::string &templateSign, const std::int classifierId) {
    // iocr识别apiUrl
    const static string recognise_api_url = "https://aip.baidubce.com/rest/2.0/solution/v1/iocr/recognise";
    // 请求模板的参数
    std::string recognise_params = "access_token=" + access_token + "&templateSign=" + templateSign + "&image=" + image_base64;
    // 请求分类器的参数
    std::string classifier_params = "access_token=" + access_token 
        + "&classifierId=" + std::to_string(classifierId) 
        + "&image=" + image_base64;
    struct curl_slist * headers = NULL;
    headers = curl_slist_append(headers, "Content-Type:application/x-www-form-urlencoded");
    headers = curl_slist_append(headers, "charset:utf-8");
    CURL *curl;
    CURLcode result_code;
    int is_success;
    curl = curl_easy_init();
    if (curl) {
        // 使用libcurl post数据：设定待post的url等
        curl_easy_setopt(curl, CURLOPT_URL, recognise_api_url.c_str());
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_POST, 1);
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false);
        curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,callback);
        // 请求模板
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, recognise_params.c_str());
        curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, recognise_params.size());
        // 请求分类器
        // curl_easy_setopt(curl, CURLOPT_POSTFIELDS, classifier_params.c_str());
        // curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, classifier_params.size());
        
        result_code = curl_easy_perform(curl);
        // http post不成功时错误处理
        if (result_code != CURLE_OK) {
            fprintf(stderr, "curl_easy_perform() failed: %s\n",
                    curl_easy_strerror(result_code));
            is_success = 1;
            return is_success;
        }
        curl_easy_cleanup(curl);
        curl_slist_free_all(headers);
        // 控制台输出识别结果
        cout << ocr_result << endl;
        is_success = 0;
    } else {
        fprintf(stderr, "curl_easy_init() failed.");
        is_success = 1;
    }
    return is_success;
}

std::string get_image_b64(const std::string &image_path) {
    ifstream f;
    f.open(image_path, ios::in | ios::binary);
    // 定位指针到文件末尾
    f.seekg(0, ios::end);
    int size = f.tellg();
    // 指针重新回到文件头部
    f.seekg(0, ios::beg);
    char* buffer = (char*)malloc(sizeof(char)*size);
    f.read(buffer,size);
    f.close();
    // base64编码
    std::string image_b64 = base64_encode(buffer, size);
    return image_b64;
}

int main() {
    std::string access_token = "your_access_token";
    std::string image_path = "your_file_path";
    std::string templateSign = "your_templateSign";
    std::int classifierId = "your_classifier_id";
    // 获取本地图片的base64
    std::string image_b64 = get_image_b64(image_path);
    // urlcode编码
    image_b64 = url_encode(image_b64);
    // 对api发送post请求
    iocr_regenize(image_b64, access_token, templateSign, classifierId);
    return 0;
}