一：VS2019配置curl庫(kù)

1、下載curl安裝包并解壓

進(jìn)入https://curl.haxx.se/download.html下載curl庫(kù)，解壓得到文件夾【curl-7.65.3】

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2城菊、編譯curl

1）雙擊運(yùn)行【curl-7.65.3】文件夾下的【buildconf.bat】
2）打開VS2019自帶的命令提示符

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3芹血、為你的項(xiàng)目配置curl

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2）選擇【你的項(xiàng)目】->【屬性】
3）選擇【配置屬性】->【VC++目錄】->【包含目錄】->添加curl-7.65.3\builds\libcurl-vc16-x86-debug-dll-ipv6-sspi-winssl\include文件夾
4）選擇【配置屬性】->【VC++目錄】->【庫(kù)目錄】->添加curl-7.65.3\curl-7.65.3\builds\libcurl-vc16-x86-debug-dll-ipv6-sspi-winssl\lib文件夾
5）選擇【配置屬性】->【c/c++】->【代碼生成】->【運(yùn)行庫(kù)】贮泞，選擇【MTd/MDd】
6）選擇【配置屬性】->【鏈接器】->【常規(guī)】->【附加庫(kù)目錄】，添加curl-7.65.3\curl-7.65.3\builds\libcurl-vc16-x86-debug-dll-ipv6-sspi-winssl\lib文件夾
7）選擇【配置屬性】->【鏈接器】->【輸入】->【附加依賴項(xiàng)】幔烛，添加lib文件：libcurl_debug.lib（編譯生成的.lib文件啃擦，在curl-7.65.3\curl-7.65.3\builds\libcurl-vc16-x86-debug-dll-ipv6-sspi-winssl\lib文件夾下）
8）點(diǎn)擊【應(yīng)用】完成配置

二：JsonRpc與以太坊交互

Json解析可參考文章：

//eth_connect.h文件
#include<curl/curl.h>
#include <string>
#include <json/json.h>
using namespace std;

CURL* curl;
CURLcode cres;

size_t write_data_a(void* buffer, size_t size, size_t nmemb, void* userp) {
    char* d = (char*)buffer;
    char* u = (char*)userp;

    strcpy(u, d);
    return nmemb;
}
bool setCurl(char* jm, struct curl_slist* headers, char* r_header, char* r_result) {
    curl = curl_easy_init();
    headers = curl_slist_append(headers, "Content-Type: application/json");
    char* body_str_json = jm;//"{\"jsonrpc\":\"2.0\",\"method\":\"personal_newAccount\",\"params\":[\""+psw+"\"],\"id\":1}";
    //響應(yīng)頭
    string address = "http://127.0.0.1";
    int port = 8545;
    string post_url = address + ":" + to_string(port);

    if (curl) {
        //設(shè)置post請(qǐng)求的url地址
        curl_easy_setopt(curl, CURLOPT_URL, post_url.c_str());
        //設(shè)置HTTP頭
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        //設(shè)置發(fā)送超時(shí)時(shí)間
        curl_easy_setopt(curl, CURLOPT_TIMEOUT, 1);
        curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, strlen(body_str_json));
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, body_str_json);
        //設(shè)置返回頭
        curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, &write_data_a);
        curl_easy_setopt(curl, CURLOPT_HEADERDATA, r_header);
        //設(shè)置響應(yīng)體
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &write_data_a);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, r_result);
        return true;
    }
    return false;
}

char* getEthereumInformation(string request) {
    curl_global_init(CURL_GLOBAL_ALL);
    cres = CURLE_OK;
    char* r_header = new char[256], * r_result = new char[2048];
    struct curl_slist* headers = NULL;

    //string tmp = "{\"jsonrpc\":\"2.0\",\"method\":\"eth_blockNumber\",\"params\":[],\"id\":1}";

    char* body_str_json = new char[strlen(tmp.c_str()) + 1];
    strcpy(body_str_json, tmp.c_str());

    if (setCurl(body_str_json, headers, r_header, r_result)) {
        //執(zhí)行單條請(qǐng)求
        //設(shè)置返回頭
        curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, &write_data_a);
        curl_easy_setopt(curl, CURLOPT_HEADERDATA, r_header);
        //設(shè)置響應(yīng)體
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &write_data_a);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, r_result);
        cres = curl_easy_perform(curl);
        curl_slist_free_all(headers);
        //這個(gè)調(diào)用用來結(jié)束一個(gè)會(huì)話.與curl_easy_init配合著用
        curl_easy_cleanup(curl);
        //在結(jié)束libcurl使用的時(shí)候，用來對(duì)curl_global_init做的工作清理饿悬。類似于close的函數(shù)
        curl_global_cleanup();
        return r_result;
    }
    return 0;
}

//test.cpp（主函數(shù)）
#include"eth_connect.h"
using namespace std;
int main() {
        //獲取區(qū)塊鏈當(dāng)前區(qū)塊高度
        string getBlockHeightJson = "{\"jsonrpc\":\"2.0\",\"method\":\"eth_blockNumber\",\"params\":[],\"id\":1}";
        char* getBlockHeight_ResultJson = getEthereumInformation(getBlockHeightJson);
        //返回的json數(shù)據(jù)格式：{"id":83,"jsonrpc" : "2.0","result" : "0x4b7" // 1207}
        //解析Json數(shù)據(jù)
        string HexBlockHeight = ReadJson(getBlockHeight_ResultJson, "result");
        //int height= HexStringToInt(HexBlockHeight);
        //HexBlockHeight = "0x" + dec2hex(round, 8);

        //根據(jù)blockNumber獲取block信息（blockHash）
        //HexBlockHeight = "0x9" ;
        string getBlockByNumberJson = "{\"jsonrpc\":\"2.0\",\"method\":\"eth_getBlockByNumber\",\"params\":[\"" + HexBlockHeight + "\", true],\"id\":1}";
        char* getBlockByNumber_ResultJson = getEthereumInformation(getBlockByNumberJson);
        string BlockHash = readJson(getBlockByNumber_ResultJson);
        //string BlockHashShort = BlockHash.substr(0, 15);
        //strcpy(seed, BlockHashShort.c_str());
        curl_global_cleanup();
    return 0;
}
string ReadJson(string str, string keyOfstr)
{
    //示例字符串
    /*string result = "{\"id\":83,\"jsonrpc\" : \"2.0\",\"result\" : \"0xc94\" }";*/
    Json::Reader reader;
    Json::Value root;
    //從字符串中讀取數(shù)據(jù)
    if (reader.parse(str, root))
    {
        std::string result = root[keyOfstr].asString();

        return result;
    }
    return "";
}
//讀取區(qū)塊hash值令蛉，響應(yīng)結(jié)果為：
//{
//"id":1,
//"jsonrpc" : "2.0",
//"result" : {
//  "hash":"0xc6ef2fc5426d6ad6fd9e2a26abeab0aa2411b7ab17f30a99d3cb96aed1d1055b",
//      "nonce" : "0x",
//      "blockHash" : "0xbeab0aa2411b7ab17f30a99d3cb9c6ef2fc5426d6ad6fd9e2a26a6aed1d1055b",
//      "blockNumber" : "0x15df", // 5599
//      "transactionIndex" : "0x1", // 1
//      "from" : "0x407d73d8a49eeb85d32cf465507dd71d507100c1",
//      "to" : "0x85h43d8a49eeb85d32cf465507dd71d507100c1",
//      "value" : "0x7f110", // 520464
//      "gas" : "0x7f110", // 520464
//      "gasPrice" : "0x09184e72a000",
//      "input" : "0x603880600c6000396000f300603880600c6000396000f3603880600c6000396000f360",
//}
//}
string readJson(string str) {
    int32_t index = str.find("{");
    if (-1 != index) {
        string resultJson = str.substr(index, str.size() - index);
        Json::Reader reader;
        Json::Value value;
        if (reader.parse(resultJson, value)) {
            if (!value["result"].isNull()) {
                Json::Value result = value["result"];
                if (!result["hash"].isNull()) {
                    const char* hash = result["hash"].asCString();
                    //memcpy(plat_user->nick_name_, name, strlen(name)); 
                    return hash;
                }
            }
            return "";
        }
    }
}