(C++) Get a Google Drive Access Token using a JSON Private Key

Demonstrates how to get a Google Drive API access token using a JSON service account private key.

Chilkat C/C++ Library Downloads
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#include <CkFileAccess.h>
#include <CkAuthGoogle.h>
#include <CkSocket.h>

void ChilkatSample(void)
    {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // First load the JSON key into a string.
    CkFileAccess fac;
    const char *jsonKey = fac.readEntireTextFile("qa_data/googleApi/chilkatcloud-b8826e030499.json","utf-8");
    if (fac.get_LastMethodSuccess() != true) {
        std::cout << fac.lastErrorText() << "\r\n";
        return;
    }

    CkAuthGoogle gAuth;
    gAuth.put_JsonKey(jsonKey);

    // Choose a scope.
    gAuth.put_Scope("https://www.googleapis.com/auth/drive");

    // Request an access token that is valid for this many seconds.
    gAuth.put_ExpireNumSeconds(3600);

    // If the application is requesting delegated access:
    // The email address of the user for which the application is requesting delegated access,
    // then set the email address here. (Otherwise leave it empty.)
    gAuth.put_SubEmailAddress("");

    // Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
    // The Chilkat socket object is used so that the connection can be established
    // through proxies or an SSH tunnel if desired.
    CkSocket tlsSock;
    bool success = tlsSock.Connect("www.googleapis.com",443,true,5000);
    if (success != true) {
        std::cout << tlsSock.lastErrorText() << "\r\n";
        return;
    }

    // Send the request to obtain the access token.
    success = gAuth.ObtainAccessToken(tlsSock);
    if (success != true) {
        std::cout << gAuth.lastErrorText() << "\r\n";
        return;
    }

    // Examine the access token:
    std::cout << "Access Token: " << gAuth.accessToken() << "\r\n";
    }