从Gmail下载邮件附件，获取Exchange [MailMessage：null]

Question

I need to download the attachments from Gmail accounts using java program. Using Apache Camel .

While running i am getting ,

Exchange[MailMessage: null], thus the attachments.size() is 0

Am posting my test code also

@Test
public void configureExcange() throws Exception {

    try {
        CamelContext context = new DefaultCamelContext();

        Endpoint endpoint =
                context.getEndpoint("imaps://imap.gmail.com?username=" + mailId + "&password=" + password
                        + "&delete=false&unseen=true&consumer.delay=60000");

        // PollingConsumer consumer = endpoint.createPollingConsumer();
        Exchange exchange = endpoint.createExchange();

        process(exchange);

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

public void process(Exchange exchange) throws Exception {
    // the API is a bit clunky so we need to loop
    Map<String, DataHandler> attachments = exchange.getIn().getAttachments();
    if (attachments.size() > 0) {
        for (String name : attachments.keySet()) {
            DataHandler dh = attachments.get(name);
            // get the file name
            String filename = dh.getName();

            // get the content and convert it to byte[]
            byte[] data = exchange.getContext().getTypeConverter().convertTo(byte[].class, dh.getInputStream());

            // write the data to a file
            FileOutputStream out = new FileOutputStream(filename);
            out.write(data);
            out.flush();
            out.close();
        }
    }
}

How can i get the attachments ?

Answer 1

Endpoint.createExchange() is just create the exchange to use , it doesn't pull the message from the mail server. You need to use ConsumerTemplate to pull the message from gmail server.

Answer 2

Updating the function, showing how to poll the mail account.

@Test
public void configureExcange() throws Exception {

    PollingConsumer pollingConsumer = null;
    try {
        CamelContext context = new DefaultCamelContext();
        Endpoint endpoint =
                context.getEndpoint("imaps://imap.gmail.com?username="
                + mailId + "&password=" + password
                + "&delete=false&peek=false&unseen=true&consumer.delay=60000&closeFolder=false&disconnect=false");
            // options unseen=true, will only poll unread mails

            //Polling an END point
            pollingConsumer = endpoint.createPollingConsumer();
            pollingConsumer.start();
            pollingConsumer.getEndpoint().createExchange();

            Exchange exchange = pollingConsumer.receive(60000);

            while (exchange != null) {
                process(exchange);
                //each time "pollingConsumer" will poll 1 mail at a time
                exchange = pollingConsumer.receive(60000);
            }
    } catch (Exception e) {
        e.printStackTrace();
    }
}