In this paper, we investigate the impact of jamming attacks on the performance of smartphones regarding their WiFi access and propose a real-time jamming detection method based on the received signal strength indicator and the packet loss rate of WiFi signals, which can be easily implemented on Android smartphones. Experiments are performed to evaluate the proposed jamming detection method, in which universal software radio peripherals are used as jammers to block the WiFi signals between smartphone phones and wireless routers. Experimental results show that the proposed application can detect jamming attacks with small false alarm rate and miss detection raaaaaate.