Is it necessary to rebuild RabbitMQ connection each time a message is to be sent

问题

I have a Spring 3 application that receives messages via a non-RabbitMQ receiver, processes them and forwards via RabbitMQ. Each time a message is to be sent a new RabbitMQ connection is built. This seems a bit wasteful. I am just wondering if this is really necessary or if there is a reason why the connection cannot be held in a Singleton and only built once (for multiple sends). This is the sending method:

private void send(String routingKey, String message) throws Exception { 
    String exchange = applicationConfiguration.getAMQPExchange();  
    String ipAddress = applicationConfiguration.getAMQPHost();
    String exchangeType = applicationConfiguration.getAMQPExchangeType();
    String password = applicationConfiguration.getAMQPUser();
    String user = applicationConfiguration.getAMQPPassword();
    String virtualHost = applicationConfiguration.getAMQPVirtualHost();
    String port = applicationConfiguration.getAMQPPort();

    ConnectionFactory factory = new ConnectionFactory();
    factory.setUsername(user);
    factory.setPassword(password);
    factory.setVirtualHost(virtualHost);
    factory.setPort(Integer.parseInt(port));
    factory.setHost(ipAddress);

    Connection connection = factory.newConnection();
    Channel channel = connection.createChannel();
    channel.exchangeDeclare(exchange, exchangeType);
    channel.basicPublish(exchange, routingKey, null, message.getBytes());

    log.debug(" [AMQP] Sent message with key {} : {}",routingKey, message);

    connection.close();
}

or a possible singleton:

public class MyConnection {
    private static MyConnection singleton = new MyConnection();
    private static Connection connection;

    private MyConnection() {
        ConnectionFactory factory = new ConnectionFactory();
        String exchange = applicationConfiguration.getAMQPExchange();  
        String ipAddress = applicationConfiguration.getAMQPHost();
        String exchangeType = applicationConfiguration.getAMQPExchangeType();
        String password = applicationConfiguration.getAMQPUser();
        String user = applicationConfiguration.getAMQPPassword();
        String virtualHost = applicationConfiguration.getAMQPVirtualHost();
        String port = applicationConfiguration.getAMQPPort();

        try {
            factory.setUsername(user);
            factory.setPassword(password);
            factory.setVirtualHost(virtualHost);
            factory.setPort(Integer.parseInt(port));
            factory.setHost(ipAddress);
            connection = factory.newConnection();
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static Connection getInstance( ) {
        return connection;
    }
}

回答1:

The connection could be a singleton, and you can share it for multiple send. The channel should be one for thread.

you code could be:

private void send(String routingKey, String message) throws Exception { 
     Connection connection = MyConnection().getInstance();

    Channel channel = connection.createChannel();
    channel.exchangeDeclare(exchange, exchangeType);
    channel.basicPublish(exchange, routingKey, null, message.getBytes());
    log.debug(" [AMQP] Sent message with key {} : {}",routingKey, message);
    channel.close();
}

You can decide to create and destroy a channel for each publish, or create it for your thread and reuse always the same channel.

EDIT** In order to create a sigleton read here: http://javarevisited.blogspot.it/2012/12/how-to-create-thread-safe-singleton-in-java-example.html

public class MySingletonConnection{
    private static final MySingletonConnection INSTANCE = new MySingletonConnection();
    private Connection myConnection;
    private Singleton(){ 
      // here you can init your connection parameter
    }

    public static MySingletonConnection getInstance(){
        return INSTANCE;
    }

 public Connection getConnection( ) {
    return connection;
}
}

This is one way to create a Singleton

private void send(String routingKey, String message) throws Exception { 
     Connection connection = MySingletonConnection().getInstance().getConnection();

来源：https://stackoverflow.com/questions/24910502/is-it-necessary-to-rebuild-rabbitmq-connection-each-time-a-message-is-to-be-sent

标签

java

Spring

RabbitMQ