查看电池的一些参数的文件路径： /sys/class/power_supply/ac/online  AC                               电源连接状态
/sys/class/power_supply/usb/online USB                                     电源连接状态
/sys/class/power_supply/battery/status                                      充电状态
/sys/class/power_supply/battery/health                                      电池状态
/sys/class/power_supply/battery/present                                  使用状态
/sys/class/power_supply/battery/capacity                                 电池level
/sys/class/power_supply/battery/batt_vol                                 电池电压
/sys/class/power_supply/battery/batt_temp                            电池温度
/sys/class/power_supply/battery/technology                                     电池技术