Use sample code to send a message to a queue-Simple Message Queue (formerly MNS)(SMQ)-阿里云帮助中心

Send messages to a Simple Message Queue (formerly MNS) (SMQ) queue using the SMQ SDK for Java, with options for delayed delivery and Base64 encoding.

Prerequisites

Before you begin, make sure that you have:

Authorization

By default, only Alibaba Cloud accounts can call the SendMessage operation. To call this operation as a Resource Access Management (RAM) user, grant the required permissions first.

Name	Value
API	`SendMessage`
Action	`mns:SendMessage`
Resource	`acs:mns:$region:$accountid:/queues/$queueName/messages`

Delayed delivery

By default, a message enters the Active state and becomes available for immediate consumption after being sent to a queue.

To delay consumption, set DelaySeconds to a value greater than 0. The message enters the Delayed state first and transitions to Active only after the specified delay period ends.

If both the message and the queue define DelaySeconds, the message-level value takes precedence.

Message body encoding

Encode the message body in Base64 to prevent errors caused by special characters. If the message body does not contain special characters, skip Base64 encoding and use the raw string methods instead.

Scenario	Send method	Receive method
Base64 encoding	`message.setMessageBody`	`message.getMessageBody`
Raw string (no encoding)	`message.setMessageBodyAsRawString`	`message.getMessageBodyAsRawString`

Send a message

This example connects to SMQ, sends messages to a queue, and handles errors.

For the complete source file, see SendMessageDemo.java on GitHub.

Step 1: Import dependencies and configure constants

import com.aliyun.mns.client.CloudAccount;
import com.aliyun.mns.client.CloudQueue;
import com.aliyun.mns.client.MNSClient;
import com.aliyun.mns.common.ClientException;
import com.aliyun.mns.common.ServiceException;
import com.aliyun.mns.common.utils.ServiceSettings;
import com.aliyun.mns.model.Message;

public class SendMessageDemo {

    // Replace with your queue name
    private static final String QUEUE_NAME = "cloud-queue-demo";

    // Read the Base64 encoding switch from the config file (default: false)
    private static final Boolean IS_BASE64 =
        Boolean.valueOf(ServiceSettings.getMNSPropertyValue("msgBodyBase64Switch", "false"));

The SDK reads the endpoint and credentials from ${"user.home"}/.aliyun-mns.properties:

mns.endpoint=http://xxxxxxx
mns.msgBodyBase64Switch=true

Step 2: Create the client

    public static void main(String[] args) {
        // Initialize the client from the config file endpoint.
        // The SDK reads the AccessKey ID and AccessKey secret from environment variables.
        CloudAccount account = new CloudAccount(ServiceSettings.getMNSAccountEndpoint());
        MNSClient client = account.getMNSClient();

Step 3: Send messages to the queue

        try {
            CloudQueue queue = client.getQueueRef(QUEUE_NAME);

            for (int i = 0; i < 10; i++) {
                Message message = new Message();
                String body = "demo_message_body" + i;

                if (IS_BASE64) {
                    // Base64-encode the message body
                    message.setMessageBody(body);
                } else {
                    // Send the message body as a raw string
                    message.setMessageBodyAsRawString(body);
                }

                Message result = queue.putMessage(message);
                System.out.println("Send message id is: " + result.getMessageId());
            }

Step 4: Handle errors and close the client

        } catch (ClientException ce) {
            System.out.println("Something wrong with the network connection between client and MNS service. "
                + "Please check your network and DNS availability.");
            ce.printStackTrace();
        } catch (ServiceException se) {
            if (se.getErrorCode().equals("QueueNotExist")) {
                System.out.println("Queue is not exist. Please create before use");
            } else if (se.getErrorCode().equals("TimeExpired")) {
                System.out.println("The request is time expired. Please check your local machine timeclock");
            }
            se.printStackTrace();
        } catch (Exception e) {
            System.out.println("Unknown exception happened!");
            e.printStackTrace();
        }

        client.close();
    }
}

Error code	Cause	Action
`QueueNotExist`	The queue does not exist	Create the queue before sending messages
`TimeExpired`	The request timestamp is out of sync	Verify the system clock on your local machine

Expected output

On success, the console prints a message ID for each message sent:

Send message id is: 5F20B000F0E94A39-1-182B5C2****
Send message id is: 5F20B000F0E94A39-1-182B5C2****
...

Endpoint selection

Choose the endpoint type based on your deployment environment:

Scenario	Endpoint type	When to use
Development and testing	Public endpoint	Access SMQ from outside the Alibaba Cloud network
Production	Internal endpoint	Access SMQ from within the same region for lower latency and no data transfer fees

For a full list of supported regions and endpoints, see Regions and endpoints.