With the wide integration of various distributed communication and control techniques, the cyber-physical microgrids face critical challenges raised by the emerging cyberattacks. This paper proposes a three-stage defensive framework for distributed microgrids against denial of service (DoS) and false data injection (FDI) attacks, including resilient control， communication network reconfiguration, and switching of local control. The resilient control in the first stage is capable of tackling simultaneous DoS and FDI attacks when the connectivity of communication network could be maintained under cyberattacks. The communication network reconfiguration method in the second stage and the subsequent switching of local control in the third stage based on the software-defined network (SDN) layer aim to cope with the network partitions caused by cyberattacks. The proposed defensive framework could effectively mitigate the impacts of a wide range of simultaneous DoS and FDI attacks in microgrids without requiring the specific assumptions of attacks and prompt detections, which would not incorporate additional cyberattack risks. Extensive case studies using a 13-bus microgrid system are conducted to validate the effectiveness of the proposed three-stage defensive framework against the simultaneous DoS and FDI attacks.