可以通过以下示例代码，使用 AWS Python SDK (Boto3) 来检查设备是否在线。

import boto3
import time

iot = boto3.client('iot')

def get_device_status(device_id):
    response = iot.describe_endpoint(endpointType='iot:Data-ATS')
    endpoint = response['endpointAddress']
    client_id = device_id + str(time.time())
    mqtt = boto3.client('iot-data', endpoint_url=endpoint)
    try:
        response = mqtt.publish(
            topic='$aws/things/{}/shadow/get'.format(device_id),
            qos=1,
            payload='{}')
        response = mqtt.subscribe(topic='$aws/things/{}/shadow/update'.format(device_id), qos=1)
        status_response = ''
        while True:
            status_response = mqtt.receive()
            if status_response.get('status'):
                break
        shadow = json.loads(status_response['payload'].decode('utf-8'))['state']['reported']
        return shadow['state']['reported']['connected']
    except Exception as e:
        print("Exception occurred: ", e)
        return False


def main():
    device_id_list = ['device_1', 'device_2', 'device_3']
    for device_id in device_id_list:
        status = get_device_status(device_id)
        print(f"Device {device_id} is online: {status}")

if __name__ == "__main__":
    main()

这个示例代码将会检查 AWS IoT 中给定设备的在线状态，使用 describe_endpoint() 函数返回 AWS IoT 数据端点的 URL，使用 MQTT 协议来进行数据传输，并对设备的在线状态进行了判断和输出。