idhttp=new TIdHTTP(NULL);
idhttp->AllowCookies =true;
idhttp->HandleRedirects =true; //允许重定向
idhttp->ConnectTimeout =20000;
idhttp->ReadTimeout =20000;
//hoInProcessAuth, hoKeepOrigProtocol, hoForceEncodeParams, hoNonSSLProxyUseConnectVerb, hoNoParseMetaHTTPEquiv, hoWaitForUnexpectedData, hoTreat302Like303, hoNoProtocolErrorException, hoNoReadMultipartMIME, hoNoParseXmlCharset, hoWantProtocolErrorContent, hoNoReadChunked
idhttp->HTTPOptions <<hoKeepOrigProtocol; //这一句很关键
//pv1_0, pv1_1
idhttp->ProtocolVersion =pv1_1;
SSLIO=new TIdSSLIOHandlerSocketOpenSSL();
//sslvSSLv2, sslvSSLv23, sslvSSLv3, sslvTLSv1, sslvTLSv1_1, sslvTLSv1_2
SSLIO->SSLOptions->Method = sslvTLSv1_2;
//sslmUnassigned, sslmClient, sslmServer, sslmBoth
SSLIO->SSLOptions->Mode = sslmClient;
SSLIO->ConnectTimeout =20000;
idhttp->IOHandler=SSLIO;
idhttp访问出现onnection closed gracefully
原文：https://www.cnblogs.com/suhq/p/13259914.html