Use the Java SDK

Call steps

1. Initialize the SDK client. For more information, see SDK Initialization.

2. Create a ${API name}+"Request" object instance named request for the API call.

3. Call the set+${Request parameter name} method on the request object to set the required request parameters.

4. Create a ${API name}+"Response" object instance named response. Call the ${API name}(request) method on the client object to get the response. The response includes the body and headers from the server.

5. Call the get+${Response parameter name} method on the body member of the response object to retrieve a response parameter value.

   For example, response.getbody.getSuccess() retrieves the success flag. Success is a common response parameter. Other common response parameters include RequestId, ErrorMessage, and Code.

6. Use the catch() method to handle exceptions.

For the full list of IoT Platform cloud APIs, see API list. For request and response parameter descriptions, see the documentation for each API.

The following example uses the Pub API to publish a message to a topic. For request parameter details, see Pub.

PubRequest request = new PubRequest()
    .setIotInstanceId("${iotInstanceId}")
    .setProductKey("${productKey}")
    .setMessageContent(Base64.getEncoder().encodeToString("hello world".getBytes()))
    .setTopicFullName("/${productKey}/${deviceName}/user/get")
    .setQos(0);// QoS 0 and QoS 1 are supported. 
try {
    PubResponse response = client.pub(request);
    // The response contains the body and headers from the server-side. 
    // Get the request ID of this call.
    System.out.println(response.getBody().getRequestId());
    // Check whether the call is successful.
    System.out.println(response.getBody().getSuccess());
    
    // The call is successful.
    if (response.getBody().getSuccess()) {
        // Get the message ID from the cloud.
        System.out.println(response.getBody().getMessageId());
        
        // Implement your business logic.
        
    } else {
    // The call failed.            
        // Get the error code for the failed call.
        System.out.println(response.getBody().getCode());
        // Get the error message for the failed call.
        System.out.println(response.getBody().getErrorMessage());
     }
} catch (TeaException error) {
    // A server-side business exception occurred.
    System.out.println(error.getCode());
    System.out.println(error.getMessage());
} catch (Exception e) {
    // Other runtime exceptions occurred.
    e.printStackTrace();
}

Complete sample code

import com.aliyun.iot20180120.Client;
import com.aliyun.iot20180120.models.PubRequest;
import com.aliyun.iot20180120.models.PubResponse;
import com.aliyun.tea.TeaException;
import com.aliyun.teaopenapi.models.Config;
import java.util.Base64;

public class IotSdkDemo {
    /**
     * Initialize the client using an AccessKey ID and AccessKey secret.
     */
    private static Client createClient(String accessKeyId, String accessKeySecret) throws Exception {
        com.aliyun.teaopenapi.models.Config config = new com.aliyun.teaopenapi.models.Config()
                // Required. Your AccessKey ID.
                .setAccessKeyId(accessKeyId)
                // Required. Your AccessKey secret.
                .setAccessKeySecret(accessKeySecret);
        // For the endpoint, see https://api.aliyun.com/product/Iot
        config.endpoint = "iot.cn-beijing.aliyuncs.com";
        return new Client(config);
    }

    public static void main(String[] args) {
        try {
            Client client = createClient(accessKey, accessKeySecret);
            PubRequest request = new PubRequest()
                .setIotInstanceId("${iotInstanceId}")
                .setProductKey("${productKey}")
                .setMessageContent(Base64.getEncoder().encodeToString("hello world".getBytes()))
                .setTopicFullName("/${productKey}/${deviceName}/user/get")
                .setQos(0);// QoS 0 and QoS 1 are supported. 
            
            PubResponse response = client.pub(request);            
            // Get the request ID of this call.
      System.out.println(response.getBody().getRequestId());
      // Check whether the call is successful.
      System.out.println(response.getBody().getSuccess());
            
         // The call is successful.
       if (response.getBody().getSuccess()) {
          // Get the message ID from the cloud.
          System.out.println(response.getBody().getMessageId());
        
          // Implement your business logic.
      } else {
       // The call failed.            
          // Get the error code for the failed call.
             System.out.println(response.getBody().getCode());
          // Get the error message for the failed call.
          System.out.println(response.getBody().getErrorMessage());
      }
        } catch (TeaException error) {
            // A server-side business exception occurred.
      System.out.println(error.getCode());
      System.out.println(error.getMessage());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}