Java Tutorial/Email/Provider

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

/*
 * @(#)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();
    }
  }
}