__int64 queryID = 12345689;
std::stringstream stream;
stream << queryID;
std::string queryID_utf8(stream.str());
std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> convert;
std::u32string queryID_utf32 = convert.from_bytes(queryID_utf8);

http_client client(U("http://localhost:8080/MyJavaWebApp"));
uri_builder builder(U("/getContent"));
builder.append_query(U("queryID"), queryID_utf32.c_str());
client.request(methods::GET, builder.to_string()) // etc.