java - ActiveMQ 中的字符串生成器

Question

因此，我有一个发送者(在本例中)向接收者发送 3 个 xml 格式的对象，但是我的字符串生成器首先打印出第一个对象，然后是第一个 + 第二个，然后是所有 3 个对象，而不是:- 先打印出来- 打印第二个- 打印第三个

这是我的代码:

public class TrackingSender {
public static void main(String[] args) {
    try {
        ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://localhost:61616");

        Connection connection = connectionFactory.createConnection();
        connection.start();

        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);

        Destination destination = session.createQueue("TEST.SENDRECEIVE");

        MessageProducer producer = session.createProducer(destination);
        producer.setDeliveryMode(DeliveryMode.PERSISTENT);
        TrackingInformatieFactory.makeTrackingInformatieList();
        List<TrackingInformatie> trackingInformatieList = TrackingInformatieFactory.getTrackingInformatieList();
        Writer writer = new StringWriter();
        TextMessage message;
        for(TrackingInformatie ti: trackingInformatieList){
            Marshaller.marshal(ti, writer);
            message = session.createTextMessage(writer.toString());
            producer.send(message);
            Thread.sleep(1000);
        }

    } catch(Exception e){
        e.printStackTrace();
    }
}

}

public class TrackingReceiver {
public static void main(String[] args) {
    try {
        ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://localhost:61616");

        Connection connection = connectionFactory.createConnection();
        connection.start();

        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
        Destination destination = session.createQueue("TEST.SENDRECEIVE");
        MessageConsumer consumer = session.createConsumer(destination);
        TextMessage message;
        Reader reader;
        StringBuilder builder;
        int charsRead;
        char[] chars;
        TrackingInformatieFactory.makeTrackingInformatieList();
        List<TrackingInformatie> trackingInformatieList = TrackingInformatieFactory.getTrackingInformatieList();
        for (int i = 0; i < trackingInformatieList.size(); i++){
            message = (TextMessage) consumer.receive();
            reader = new StringReader(message.getText());
            builder = new StringBuilder();
            chars = new char[100];
            charsRead = -1;
        do{
            charsRead = reader.read(chars,0,chars.length);
            //if we have valid chars, append them to end of string.
            if(charsRead>0)
                builder.append(chars,0,charsRead);
        }
        while(charsRead>0);
            String stringReadFromReader = builder.toString();
            System.out.println("String read = " + stringReadFromReader);

        }
    }
    catch (Exception e) {
        e.printStackTrace();
    }
}
} 

Answer 1

在你的 Producer 中，你永远不会重新初始化你的 writer。因此，您发送的消息实际上包含第一个对象、第一个对象和第二个对象，然后包含所有三个对象。更改生产者代码以在 for 循环内而不是之前初始化 StringWriter。