In the mobile internet era, location-based services have been widely used in mobile applications for delivering novel services to end-users. As battery technologies have long been the bottleneck holding back the development of mobile applications, a large body of research has focused on saving energy. This paper proposes an adaptive middleware architecture for mobile applications using location-based services. We have developed this solution after analyzing popular positioning techniques, such as GPS, Wi-Fi, and Cell Towers. The proposed middleware is adopted to connect the upper layer of location-based applications with the lower hardware layer of the host mobile phone. Adaptive location sensor policies, scenarios adapters and mechanism managers are used to identify the optimal energy-saving positioning methods. To verify the validity of this novel architecture, a preliminary application with GPS and Cell-Tower functionality is implemented and analyzed. The proposed architecture is evaluated both in theory and by experimentation.