JavaMail API - Pobieranie wiadomości e-mail

W poprzednim rozdziale dowiedzieliśmy się, jak sprawdzać e-maile. Zobaczmy teraz, jak pobrać każdą wiadomość e-mail i przeczytać jej zawartość. Napiszmy klasę JavyFetchingEmail który odczyta następujące typy e-maili:

  • Prosty e-mail

  • E-mail z załącznikiem

  • E-mail z wbudowanym obrazem

Podstawowe kroki w kodzie są następujące:

  • Pobierz obiekt Session.

  • Utwórz obiekt sklepu POP3 i połącz się ze sklepem.

  • Utwórz obiekt folderu i otwórz odpowiedni folder w swojej skrzynce pocztowej.

  • Pobierz wiadomości.

  • Zamknij folder i odpowiednio przechowuj obiekty.

Utwórz klasę Java

Utwórz plik klasy Java FetchingEmailktórych zawartość jest jak poniżej:

package com.tutorialspoint;

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Date;
import java.util.Properties;

import javax.mail.Address;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.NoSuchProviderException;
import javax.mail.Part;
import javax.mail.Session;
import javax.mail.Store;

public class FetchingEmail {

   public static void fetch(String pop3Host, String storeType, String user,
      String password) {
      try {
         // create properties field
         Properties properties = new Properties();
         properties.put("mail.store.protocol", "pop3");
         properties.put("mail.pop3.host", pop3Host);
         properties.put("mail.pop3.port", "995");
         properties.put("mail.pop3.starttls.enable", "true");
         Session emailSession = Session.getDefaultInstance(properties);
         // emailSession.setDebug(true);

         // create the POP3 store object and connect with the pop server
         Store store = emailSession.getStore("pop3s");

         store.connect(pop3Host, user, password);

         // create the folder object and open it
         Folder emailFolder = store.getFolder("INBOX");
         emailFolder.open(Folder.READ_ONLY);

         BufferedReader reader = new BufferedReader(new InputStreamReader(
	      System.in));

         // retrieve the messages from the folder in an array and print it
         Message[] messages = emailFolder.getMessages();
         System.out.println("messages.length---" + messages.length);

         for (int i = 0; i < messages.length; i++) {
            Message message = messages[i];
            System.out.println("---------------------------------");
            writePart(message);
            String line = reader.readLine();
            if ("YES".equals(line)) {
               message.writeTo(System.out);
            } else if ("QUIT".equals(line)) {
               break;
            }
         }

         // close the store and folder objects
         emailFolder.close(false);
         store.close();

      } catch (NoSuchProviderException e) {
         e.printStackTrace();
      } catch (MessagingException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
   public static void main(String[] args) {

      String host = "pop.gmail.com";// change accordingly
      String mailStoreType = "pop3";
      String username = 
         "[email protected]";// change accordingly
      String password = "*****";// change accordingly

      //Call method fetch
      fetch(host, mailStoreType, username, password);

   }

   /*
   * This method checks for content-type 
   * based on which, it processes and
   * fetches the content of the message
   */
   public static void writePart(Part p) throws Exception {
      if (p instanceof Message)
         //Call methos writeEnvelope
         writeEnvelope((Message) p);

      System.out.println("----------------------------");
      System.out.println("CONTENT-TYPE: " + p.getContentType());

      //check if the content is plain text
      if (p.isMimeType("text/plain")) {
         System.out.println("This is plain text");
         System.out.println("---------------------------");
         System.out.println((String) p.getContent());
      } 
      //check if the content has attachment
      else if (p.isMimeType("multipart/*")) {
         System.out.println("This is a Multipart");
         System.out.println("---------------------------");
         Multipart mp = (Multipart) p.getContent();
         int count = mp.getCount();
         for (int i = 0; i < count; i++)
            writePart(mp.getBodyPart(i));
      } 
      //check if the content is a nested message
      else if (p.isMimeType("message/rfc822")) {
         System.out.println("This is a Nested Message");
         System.out.println("---------------------------");
         writePart((Part) p.getContent());
      } 
      //check if the content is an inline image
      else if (p.isMimeType("image/jpeg")) {
         System.out.println("--------> image/jpeg");
         Object o = p.getContent();

         InputStream x = (InputStream) o;
         // Construct the required byte array
         System.out.println("x.length = " + x.available());
         while ((i = (int) ((InputStream) x).available()) > 0) {
            int result = (int) (((InputStream) x).read(bArray));
            if (result == -1)
         int i = 0;
         byte[] bArray = new byte[x.available()];

            break;
         }
         FileOutputStream f2 = new FileOutputStream("/tmp/image.jpg");
         f2.write(bArray);
      } 
      else if (p.getContentType().contains("image/")) {
         System.out.println("content type" + p.getContentType());
         File f = new File("image" + new Date().getTime() + ".jpg");
         DataOutputStream output = new DataOutputStream(
            new BufferedOutputStream(new FileOutputStream(f)));
            com.sun.mail.util.BASE64DecoderStream test = 
                 (com.sun.mail.util.BASE64DecoderStream) p
                  .getContent();
         byte[] buffer = new byte[1024];
         int bytesRead;
         while ((bytesRead = test.read(buffer)) != -1) {
            output.write(buffer, 0, bytesRead);
         }
      } 
      else {
         Object o = p.getContent();
         if (o instanceof String) {
            System.out.println("This is a string");
            System.out.println("---------------------------");
            System.out.println((String) o);
         } 
         else if (o instanceof InputStream) {
            System.out.println("This is just an input stream");
            System.out.println("---------------------------");
            InputStream is = (InputStream) o;
            is = (InputStream) o;
            int c;
            while ((c = is.read()) != -1)
               System.out.write(c);
         } 
         else {
            System.out.println("This is an unknown type");
            System.out.println("---------------------------");
            System.out.println(o.toString());
         }
      }

   }
   /*
   * This method would print FROM,TO and SUBJECT of the message
   */
   public static void writeEnvelope(Message m) throws Exception {
      System.out.println("This is the message envelope");
      System.out.println("---------------------------");
      Address[] a;

      // FROM
      if ((a = m.getFrom()) != null) {
         for (int j = 0; j < a.length; j++)
         System.out.println("FROM: " + a[j].toString());
      }

      // TO
      if ((a = m.getRecipients(Message.RecipientType.TO)) != null) {
         for (int j = 0; j < a.length; j++)
         System.out.println("TO: " + a[j].toString());
      }

      // SUBJECT
      if (m.getSubject() != null)
         System.out.println("SUBJECT: " + m.getSubject());

   }

}
Możesz włączyć debugowanie, usuwając komentarz z instrukcji emailSession.setDebug (true);

Skompiluj i uruchom

Teraz, gdy nasza klasa jest gotowa, skompilujmy powyższą klasę. Zapisałem klasę FetchingEmail.java w katalogu:/home/manisha/JavaMailAPIExercise. Potrzebowalibyśmy jars javax.mail.jar i aktywacja.jar w ścieżce klas. Wykonaj poniższe polecenie, aby skompilować klasę (oba słoiki są umieszczone w katalogu / home / manisha /) z wiersza polecenia:

javac -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: FetchingEmail.java

Teraz, gdy klasa jest skompilowana, wykonaj poniższe polecenie, aby uruchomić:

java -cp /home/manisha/activation.jar:/home/manisha/javax.mail.jar: FetchingEmail

Sprawdź wyjście

W konsoli poleceń powinien pojawić się następujący komunikat:

messages.length---3
---------------------------------
This is the message envelope
---------------------------
FROM: XYZ <[email protected]>
TO: ABC <[email protected]>
SUBJECT: Simple Message
----------------------------
CONTENT-TYPE: multipart/alternative; boundary=047d7b343d6ad3e4ea04e8ec6579
This is a Multipart
---------------------------

----------------------------
CONTENT-TYPE: text/plain; charset=ISO-8859-1
This is plain text
---------------------------
Hi am a simple message string....

-- 
Regards
xyz

This is the message envelope
---------------------------
FROM: XYZ <[email protected]>
TO: ABC <[email protected]>
SUBJECT: Attachement
----------------------------
CONTENT-TYPE: multipart/mixed; boundary=047d7b343d6a99180904e8ec6751
This is a Multipart
---------------------------

----------------------------
CONTENT-TYPE: text/plain; charset=ISO-8859-1
This is plain text
---------------------------
Hi I've an attachment.Please check

-- 
Regards
XYZ

----------------------------
CONTENT-TYPE: application/octet-stream; name=sample_attachement
This is just an input stream
---------------------------
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This is the message envelope
---------------------------
FROM: XYZ <[email protected]>
TO: ABC <[email protected]>
SUBJECT: Inline Image
----------------------------
CONTENT-TYPE: multipart/related; boundary=f46d04182582be803504e8ece94b
This is a Multipart
---------------------------

----------------------------
CONTENT-TYPE: text/plain; charset=ISO-8859-1
This is plain text
---------------------------
Hi I've an inline image


[image: Inline image 3]

-- 
Regards
XYZ

----------------------------
CONTENT-TYPE: image/png; name="javamail-mini-logo.png"
content typeimage/png; name="javamail-mini-logo.png"

Tutaj możesz zobaczyć, że w naszej skrzynce pocztowej są trzy e-maile. Najpierw zwykły e-mail z wiadomością „Cześć, jestem prostym ciągiem wiadomości…”. Druga wiadomość zawiera załącznik. Zawartość załącznika jest również drukowana, jak pokazano powyżej. Trzecia wiadomość zawiera wbudowany obraz.

ja/tutorial
es/tutorial
de/tutorial
fr/tutorial
th/tutorial
pt/tutorial
ru/tutorial
vi/tutorial
it/tutorial
ko/tutorial
tr/tutorial
id/tutorial
pl/tutorial
hi/tutorial
japost
espost
depost
frpost
thpost
ptpost
rupost
vipost
itpost
kopost
trpost
idpost
plpost
hipost

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