Java Tutorial/Email/Provider

How to query the registry for available Providers and set default providers

   <source lang="java">

/*

* @(#)registry.java  1.9 01/05/23
*
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import java.util.Properties; import javax.mail.MessagingException; import javax.mail.NoSuchProviderException; import javax.mail.Provider; import javax.mail.Session; import javax.mail.internet.InternetAddress; import javax.mail.internet.NewsAddress; /**

* This class demonstrates how to query the registry for available Providers,
* set default providers, etc. See section 5.2 in the JavaMail 1.0 Spec for
* details on how to use the registry.
* 
* See the comments inline for what"s happening.
* 
* @author Max Spivak
*/

public class registry {

 // let"s remember a few providers
 static Provider _aProvider, _bProvider, _sunSMTP, _sunIMAP;
 public static void main(String[] args) {
   Properties props = new Properties();
   // set smtp and imap to be our default
   // transport and store protocols, respectively
   props.put("mail.transport.protocol", "smtp");
   props.put("mail.store.protocol", "imap");
   // 
   props.put("mail.smtp.class", "com.sun.mail.smtp.SMTPTransport");
   props.put("mail.imap.class", "com.sun.mail.imap.IMAPStore");
   Session session = Session.getInstance(props, null);
   // session.setDebug(true);
   // Retrieve all configured providers from the Session
   System.out.println("\n------ getProviders()----------");
   Provider[] providers = session.getProviders();
   for (int i = 0; i < providers.length; i++) {
     System.out.println("** " + providers[i]);
     // let"s remember some providers so that we can use them later
     // (I"m explicitly showing multiple ways of testing Providers)
     // BTW, no Provider "ACME Corp" will be found in the default
     // setup b/c its not in any javamail.providers resource files
     String s = null;
     if (((s = providers[i].getVendor()) != null) && s.startsWith("ACME Corp")) {
       _aProvider = providers[i];
     }
     // this Provider won"t be found by default either
     if (providers[i].getClassName().endsWith("application.smtp"))
       _bProvider = providers[i];
     // this Provider will be found since com.sun.mail.imap.IMAPStore
     // is configured in javamail.default.providers
     if (providers[i].getClassName().equals("com.sun.mail.imap.IMAPStore")) {
       _sunIMAP = providers[i];
     }
     // this Provider will be found as well since there is a
     // Sun Microsystems SMTP transport configured by
     // default in javamail.default.providers
     if (((s = providers[i].getVendor()) != null) && s.startsWith("Sun Microsystems")
         && providers[i].getType() == Provider.Type.TRANSPORT
         && providers[i].getProtocol().equalsIgnoreCase("smtp")) {
       _sunSMTP = providers[i];
     }
   }
   System.out.println("\n------ initial protocol defaults -------");
   try {
     System.out.println("imap: " + session.getProvider("imap"));
     System.out.println("smtp: " + session.getProvider("smtp"));
     // the NNTP provider will fail since we don"t have one configured
     System.out.println("nntp: " + session.getProvider("nntp"));
   } catch (NoSuchProviderException mex) {
     System.out
         .println(">> This exception is OK since there is no NNTP Provider configured by default");
     mex.printStackTrace();
   }
   System.out.println("\n------ set new protocol defaults ------");
   // set some new defaults
   try {
     // since _aProvider isn"t configured, this will fail
     session.setProvider(_aProvider); // will fail
   } catch (NoSuchProviderException mex) {
     System.out.println(">> Exception expected: _aProvider is null");
     mex.printStackTrace();
   }
   try {
     // _sunIMAP provider should"ve configured correctly; should work
     session.setProvider(_sunIMAP);
   } catch (NoSuchProviderException mex) {
     mex.printStackTrace();
   }
   try {
     System.out.println("imap: " + session.getProvider("imap"));
     System.out.println("smtp: " + session.getProvider("smtp"));
   } catch (NoSuchProviderException mex) {
     mex.printStackTrace();
   }
   System.out.println("\n\n----- get some stores ---------");
   // multiple ways to retrieve stores. these will print out the
   // string "imap:" since its the URLName for the store
   try {
     System.out.println("getStore(): " + session.getStore());
     System.out.println("getStore(Provider): " + session.getStore(_sunIMAP));
   } catch (NoSuchProviderException mex) {
     mex.printStackTrace();
   }
   try {
     System.out.println("getStore(imap): " + session.getStore("imap"));
     // pop3 will fail since it doesn"t exist
     System.out.println("getStore(pop3): " + session.getStore("pop3"));
   } catch (NoSuchProviderException mex) {
     System.out.println(">> Exception expected: no pop3 provider");
     mex.printStackTrace();
   }
   System.out.println("\n\n----- now for transports/addresses ---------");
   // retrieve transports; these will print out "smtp:" (like stores did)
   try {
     System.out.println("getTransport(): " + session.getTransport());
     System.out.println("getTransport(Provider): " + session.getTransport(_sunSMTP));
     System.out.println("getTransport(smtp): " + session.getTransport("smtp"));
     System.out.println("getTransport(Address): "
         + session.getTransport(new InternetAddress("mspivak@apilon")));
     // News will fail since there"s no news provider configured
     System.out.println("getTransport(News): "
         + session.getTransport(new NewsAddress("rec.humor")));
   } catch (MessagingException mex) {
     System.out.println(">> Exception expected: no news provider configured");
     mex.printStackTrace();
   }
 }

}</source>