We proposed and demonstrated a tunable injection-locked laser, which can be locked in a wide range. It can also be used in cascaded injection locking lasers to decrease the influence of the temperature drift. Based on this technology, a photonic scanning receiver is proposed to implement wide-range microwave frequency measurement. The receiver applies optical frequency scanning to simplify the channelization. In the experiment, the receiver can measure weak microwave signals within the frequency of 16.5 GHz.