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我剛剛開始使用Java ee 7,這是我無法想象它是如何神奇地工作的。Java ee jms現場背後的魔力是什麼?
我遵循Antonio Goncalves撰寫的Beginning Java EE 7一書中的例子。我設法編譯和部署了第13章(關於JMS)的代碼,沒有任何問題。消息按預期發送和接收,但這使我感到困惑。
源代碼是消費者類,生產者類,POJO和MDB類的組合。
這裏是消費者:
public class OrderConsumer {
public static void main(String[] args) throws NamingException {
// Gets the JNDI context
Context jndiContext = new InitialContext();
// Looks up the administered objects
ConnectionFactory connectionFactory = (ConnectionFactory) jndiContext.lookup("jms/javaee7/ConnectionFactory");
Destination topic = (Destination) jndiContext.lookup("jms/javaee7/Topic");
// Loops to receive the messages
System.out.println("\nInfinite loop. Waiting for a message...");
try (JMSContext jmsContext = connectionFactory.createContext()) {
while (true) {
OrderDTO order = jmsContext.createConsumer(topic).receiveBody(OrderDTO.class);
System.out.println("Order received: " + order);
}
}
}
}
生產者:
public class OrderProducer {
public static void main(String[] args) throws NamingException {
if (args.length != 1) {
System.out.println("usage : enter an amount");
System.exit(0);
}
System.out.println("Sending message with amount = " + args[0]);
// Creates an orderDto with a total amount parameter
Float totalAmount = Float.valueOf(args[0]);
OrderDTO order = new OrderDTO(1234l, new Date(), "Serge Gainsbourg", totalAmount);
// Gets the JNDI context
Context jndiContext = new InitialContext();
// Looks up the administered objects
ConnectionFactory connectionFactory = (ConnectionFactory) jndiContext.lookup("jms/javaee7/ConnectionFactory");
Destination topic = (Destination) jndiContext.lookup("jms/javaee7/Topic");
try (JMSContext jmsContext = connectionFactory.createContext()) {
// Sends an object message to the topic
jmsContext.createProducer().setProperty("orderAmount", totalAmount).send(topic, order);
System.out.println("\nOrder sent : " + order.toString());
}
}
}
的MDB:MSG的
@MessageDriven(mappedName = "jms/javaee7/Topic", activationConfig = {
@ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge"),
@ActivationConfigProperty(propertyName = "messageSelector", propertyValue = "orderAmount > 1000")
})
public class ExpensiveOrderMDB implements MessageListener {
public void onMessage(Message message) {
try {
OrderDTO order = message.getBody(OrderDTO.class);
System.out.println("Expensive order received: " + order.toString());
} catch (JMSException e) {
e.printStackTrace();
}
}
}
內容封裝在一個實現Serializable
接口
ExpensiveOrderMDB
和POJO打包在一個.jar文件中,並部署在本地運行的glassfish服務器中。連接和desitination資源由asadmin
創建。
問題是:消費者和生產者如何知道連接和目的地在本地glassfish服務器上可用,以便進行連接併發送/接收消息? (創建連接和目的地的行對本地glassfish服務器沒有任何說明)