android - 在没有用户交互的情况下在 Android 中发送电子邮件

Question

我想使用用户已经设置的任何默认邮件提供商在我的应用程序中发送电子邮件。必须能够在不需要任何用户交互的情况下发送电子邮件。如果我可以避免显示任何 UI，那将是最好的解决方案。不可接受的一件事是硬编码或要求用户输入他们的电子邮件凭据。用户必须已经使用他们的凭据设置了他们的帐户，例如 Gmail。我的应用程序所做的只是使用已设置的现有电子邮件提供商。

我在这里找到的大多数帖子都使用 Intent，但据我了解，这将显示电子邮件 UI 并要求用户按下发送按钮。

Answer 1

After some more digging around, I think there is a solution. Google has now added support for Gmail authentication using OAuth 2.0 which avoids the need to access the user's username and password. Since my app will require the user to have a Gmail account, this might be the solution. Of course this won't work for any other e-mail provider that doesn't support OAuth but since Google is concerned about protecting username/passwords, this approach seems to be right. Need to look into how to use OAuth from within my app, but theoretically it should be possible. Once a user grants permission to a Google service, the app receives a token that is used for the lifetime that the permission remains. The question that is still unresolved is whether Gmail supports sending an e-mail using OAuth:

Google Brings OAuth 2.0 Support To Gmail And Google Talk To Make Third-Party Apps More Secure

OAuth2 Support for Gmail

Google's sample code for Gmail support and OAuth2

Android app demonstrating how to send e-mail using OAuth

YouTube video showing how a mobile app uses 2 step verification in an app

Android docs on using OAuth 2.0

Code sample to send e-mail using OAuth2

Answer 2

试试这个代码...

public class SendAttachment{
                        public static void main(String [] args){ 
                 //to address
                        String to="abc@abc.com";//change accordingly
                        //from address
                        final String user="efg@efg.com";//change accordingly
                        final String password="password";//change accordingly 
                         MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap();
                       mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
                      mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
                      mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
                      mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
                      mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
                      CommandMap.setDefaultCommandMap(mc); 
                      //1) get the session object   
                      Properties properties = System.getProperties();
                      properties.put("mail.smtp.port", "465"); 
                      properties.put("mail.smtp.host", "smtp.gmail.com");
                        properties.put("mail.smtp.socketFactory.port", "465");
                        properties.put("mail.smtp.socketFactory.class",
                                "javax.net.ssl.SSLSocketFactory");
                        properties.put("mail.smtp.auth", "true");
                        properties.put("mail.smtp.port", "465");

                      Session session = Session.getDefaultInstance(properties,
                       new javax.mail.Authenticator() {
                       protected PasswordAuthentication getPasswordAuthentication() {
                       return new PasswordAuthentication(user,password);
                       }
                      });

                      //2) compose message   
                      try{ 
                        MimeMessage message = new MimeMessage(session);
                        message.setFrom(new InternetAddress(user));
                        message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));
                        message.setSubject("Hii"); 
                        //3) create MimeBodyPart object and set your message content    
                        BodyPart messageBodyPart1 = new MimeBodyPart();
                        messageBodyPart1.setText("How is This"); 
                        //4) create new MimeBodyPart object and set DataHandler object to this object    
                        MimeBodyPart messageBodyPart2 = new MimeBodyPart();
                    //Location of file to be attached
                        String filename = Environment.getExternalStorageDirectory().getPath()+"/R2832.zip";//change accordingly
                        DataSource source = new FileDataSource(filename);
                        messageBodyPart2.setDataHandler(new DataHandler(source));
                        messageBodyPart2.setFileName("Hello"); 
                        //5) create Multipart object and add MimeBodyPart objects to this object    
                        Multipart multipart = new MimeMultipart();
                        multipart.addBodyPart(messageBodyPart1);
                        multipart.addBodyPart(messageBodyPart2); 
                        //6) set the multiplart object to the message object
                        message.setContent(multipart ); 
                        //7) send message 
                        Transport.send(message); 
                       System.out.println("MESSAGE SENT....");
                       }catch (MessagingException ex) {ex.printStackTrace();}
                      }
                    }