如果您已经进行了基本配置，包括AWS SDK并导入必要的库以使其工作。
您需要初始化AWS IoT和Cognito客户端：

String userPoolId = "your-user-pool-id";
String clientId = "your-client-id";
String username = "user-username"; // username you want to authenticate

CognitoCredentialsProvider credentialsProvider = CognitoCredentialsProvider.builder()
        .clientId(clientId)
        .cognitoIdentityProviderClient(yourCognitoClient)
        .build();

Region region = Region.YOUR_REGION; // Replace with your AWS region

IotClient iotClient = IotClient.builder().region(region).build();
IotDataPlaneClient dataPlaneClient = IotDataPlaneClient.builder().region(region).build();

创建新的MQTT客户端：

AwsIotMqttConnectionBuilder builder = AwsIotMqttConnectionBuilder.newMqttConnectionBuilder("your-iot-endpoint")
        .clientId("your-client-id")
        .credentialsProvider(credentialsProvider)
        .region(region)
        .protocol(AwsIotMqttConnectionBuilder.Protocol.WSS);

确保Cognito用户与IoT策略相关联。下面是一个如何对Cognito用户实施策略的示例：

String policyName = "your-iot-policy-name";

AttachPolicyRequest attachPolicyRequest =
AttachPolicyRequest.builder()
        .policyName(policyName)
        .target(yourCognitoIdentityId) // Replace with your Cognito Identity ID
        .build();
 
iotClient.attachPolicy(attachPolicyRequest);

连接到AWS IoT MQTT：

AwsIotMqttConnection connection = builder.build();
connection.connect();

这只是使用Cognito的AWS IoT的基本连接实现，但它可能会帮助您弄清楚如何做到这一点。：）