关于c++:C调用HTTP接口发送带UTF8编码的请求

参考了文章：
https://blog.csdn.net/breakso…
https://blog.csdn.net/barry10…
https://blog.csdn.net/elaine_…
https://blog.csdn.net/yuanwow…
https://blog.csdn.net/erdong1…
以及微软的官网文档。

通过比拟 WinHttp、WinINet、libcurl，我决定用看起来最专精就是给 http 用的 WinHttp，反正需要也很简略，大略不太须要扩大。

需要：发送申请，带有几个 value 短的参数，和一个 value 长度不定的参数，并接管返回数据。

#include <string>
#include <iostream>
#include <windows.h>
#include <winhttp.h> 
#include <atlstr.h>
#pragma comment(lib,"winhttp.lib")
#pragma comment(lib,"user32.lib")
using namespace std;

BOOL HttpSend(wchar_t* pwszType, wchar_t* pwszIp, WORD nServerPort, wchar_t* pwcsSourcePath, char* content, char* pszOutData)
//pwszType: http verb
//pwszIp: ip
//pwcsSourcePath: url path
//content: parameters and text
{
    DWORD  dwSize = 0;
    wchar_t*  lpHeadBuffer = NULL;
    HINTERNET  hSession = NULL;
    HINTERNET  hConnect = NULL;
    HINTERNET  hRequest = NULL;
    BOOL  bResults = FALSE;
    BOOL  bUTF8Code = TRUE;

    //Obtain a session handle
    hSession = WinHttpOpen(L"User Agent", WINHTTP_ACCESS_TYPE_DEFAULT_PROXY, WINHTTP_NO_PROXY_NAME, WINHTTP_NO_PROXY_BYPASS, 0);
    if(!hSession)
    {
        cout << "Open failed!" << endl;
        return FALSE;
    }

    //Specify an HTTP server with ip and port
    hConnect = WinHttpConnect(hSession, pwszIp, nServerPort, 0);
    if(!hConnect)
    {
        cout << "Connect failed!" << endl;
        return FALSE;
    }

    //Create an HTTP request handle
    hRequest = WinHttpOpenRequest(hConnect, pwszType, pwcsSourcePath, NULL, WINHTTP_NO_REFERER, WINHTTP_DEFAULT_ACCEPT_TYPES, 0);
    if(!hRequest)
    {
        cout << "Open request failed!" << endl;
        return FALSE;
    }

    //Add header
    std::wstring wstrHeader[] = { L"Content-type: application/x-www-form-urlencoded\r\n"};
    WinHttpAddRequestHeaders(hRequest, wstrHeader[0].c_str(), wstrHeader[0].length(), WINHTTP_ADDREQ_FLAG_ADD);
    
    //Send a request
    /*USES_CONVERSION;
    std::string strExtInfo = CW2A(content, CP_UTF8);    //get content
    DWORD dwTotal = strExtInfo.length();*/
    DWORD dwTotal = strlen(content);
    //bResults = WinHttpSendRequest(hRequest, wstrHeader[0].c_str(), wstrHeader[0].length(), WINHTTP_NO_REQUEST_DATA, 0, dwTotal, 0);
    bResults = WinHttpSendRequest(hRequest, WINHTTP_NO_ADDITIONAL_HEADERS, 0, WINHTTP_NO_REQUEST_DATA, 0, dwTotal, 0);
    if(!bResults)
    {
        cout << "SendRequest failed!" << endl;
        return FALSE;
    }

    //Write data to the server
    bResults = WinHttpWriteData(hRequest, content, dwTotal, NULL);
    if(!bResults)
    {
        cout << "WriteData failed!" << endl;
        return FALSE;
    }

    //End the request, receive response from server
    bResults = WinHttpReceiveResponse(hRequest,NULL);

    //Get header info
    if(bResults)
    {bResults=WinHttpQueryHeaders(hRequest, WINHTTP_QUERY_RAW_HEADERS_CRLF, WINHTTP_HEADER_NAME_BY_INDEX, NULL, &dwSize, WINHTTP_NO_HEADER_INDEX);
        //Allocate buffer by header length
        if(GetLastError() == ERROR_INSUFFICIENT_BUFFER)
        //If the function fails and ERROR_INSUFFICIENT_BUFFER is returned, lpdwBufferLength specifies the number of bytes that the application must allocate to receive the string.
        {lpHeadBuffer = new wchar_t[dwSize / sizeof(wchar_t)];
            bResults = WinHttpQueryHeaders(hRequest,WINHTTP_QUERY_RAW_HEADERS_CRLF,WINHTTP_HEADER_NAME_BY_INDEX, lpHeadBuffer, &dwSize,WINHTTP_NO_HEADER_INDEX);
        }
        //Get Content-Type from header to specify encoding
        if (NULL != wcsstr(lpHeadBuffer, L"charset=gbk") )
        {bUTF8Code = FALSE;}
    }
    else
    {cout << "Get header failed!" << endl;}
    printf("Header contents: \n%S", lpHeadBuffer);
    delete [] lpHeadBuffer;

    //Get data from server
    LPSTR pszOutBuffer = NULL;
    DWORD dwDownloaded = 0;
    wchar_t *pwText = NULL;
    int nSize = 0;
    if (bResults)
    {
        do
        {
            //Check for available data to get data size in bytes
            dwSize = 0;
            if (!WinHttpQueryDataAvailable(hRequest, &dwSize)){cout << "Error：WinHttpQueryDataAvailable failed：" << GetLastError() << endl;
                bResults = FALSE;
                break;
            }           
            if (!dwSize)    
            {break;  //data size 0}

            //Allocate buffer by data size
            pszOutBuffer = new char[dwSize + 1];
            if (!pszOutBuffer)
            {
                cout<<"Out of memory."<<endl;
                bResults = FALSE;
                break;
            }
            ZeroMemory(pszOutBuffer, dwSize + 1);

            //Read data from server
            if (!WinHttpReadData(hRequest, pszOutBuffer, dwSize, &dwDownloaded))
            {cout << "Error：WinHttpQueryDataAvailable failed：" << GetLastError() << endl;
            }
            if (!dwDownloaded)
            {delete [] pszOutBuffer;
                bResults = FALSE;
                break;
            }

            if (FALSE == bUTF8Code)
            {
                //Transcoding to UTF-8
                int len = MultiByteToWideChar(CP_ACP, 0, pszOutBuffer, -1, NULL, 0);    //If the function succeeds and cchWideChar is 0, the return value is the required size, in characters, for the buffer indicated by lpWideCharStr
                wchar_t* pwszUnicode = new wchar_t[len];
                memset(pwszUnicode, 0, sizeof(wchar_t) * len);
                MultiByteToWideChar(CP_ACP, 0, pszOutBuffer, -1, pwszUnicode, len);        //map to wide char
                int transLen = WideCharToMultiByte(CP_UTF8, 0, pwszUnicode, len, NULL, 0, NULL, NULL);    //get length
                nSize += transLen;
                WideCharToMultiByte(CP_UTF8, 0, pwszUnicode,len, pszOutData+strlen(pszOutData), transLen, NULL, NULL);    //transcoding
            }
            else
            {strcpy_s(pszOutData + nSize, strlen(pszOutBuffer) + 1, pszOutBuffer);    //SizeInBytes should not less than src length(including '\0')
                nSize += strlen(pszOutBuffer) + 1;
            }
            delete [] pszOutBuffer;} while (dwSize > 0);

        if (hRequest) WinHttpCloseHandle(hRequest);
        if (hConnect) WinHttpCloseHandle(hConnect);
        if (hSession) WinHttpCloseHandle(hSession);

        return bResults;
    }
}

为了满足 UTF- 8 编码的要求，输入输出还要有 ANSI 和 UTF- 8 格局的相互转换：

char* Ansi2Utf8(string content)
{int nLen = MultiByteToWideChar(CP_ACP, NULL, content.c_str(), content.length(), NULL, 0);
    wchar_t* wszText = new wchar_t[nLen + 1];
    nLen = MultiByteToWideChar(CP_ACP, NULL, content.c_str(), content.length(), wszText, nLen);
    wszText[nLen] = '\0';
    nLen = WideCharToMultiByte(CP_UTF8, NULL, wszText, -1, NULL, NULL, NULL, NULL);
    char* contextBuf = new char[nLen];
    nLen = WideCharToMultiByte(CP_UTF8, NULL, wszText, -1, contextBuf, nLen, NULL, NULL);
    contextBuf[nLen] = '\0';

    return contextBuf;
}

char* Utf82Ansi(char* res)
{int len = MultiByteToWideChar(CP_UTF8, 0, res, -1, NULL, 0);
    wchar_t* wstr = new wchar_t[len + 1];
    memset(wstr, 0, len + 1);
    MultiByteToWideChar(CP_UTF8, 0, res, -1, wstr, len);
    len = WideCharToMultiByte(CP_ACP, 0, wstr, -1, NULL, 0, NULL, NULL);
    char* str = new char[len + 1];
    memset(str, 0, len + 1);
    WideCharToMultiByte(CP_ACP, 0, wstr, -1, str, len, NULL, NULL);

    return str;
}

最初调用

    string text = "xxxx";
    string content = "&key=value&..." + text;
    //trans ansi text to UTF-8 //Assume that input encoding = UTF-8
    char* contextBuf = Ansi2Utf8(content);
    
    wchar_t verb[] = L"POST";
    wchar_t ip[] = L"(IP 地址)";
    WORD port = 端口号;
    wchar_t path[] = L"门路";
    char res[1000];
    memset(res, 0, 1000);
    BOOL bRet = HttpSend(verb, ip, port, path, contextBuf, res);
    if (!bRet)
    {system("pause");
        return -1;
    }

    char* transText = Utf82Ansi(res);

    cout << "Original text:" << text << endl;
    cout << "Translation:" << transText << endl;
    system("pause");

两头掉了有数坑，ANSI 转码到 UTF- 8 如同还不是间接的……记录一下。