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This article mainly introduces "how to use spring boot to send email". In daily operation, I believe many people have doubts about how to use spring boot to send email. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts about "how to use spring boot to send email"! Next, please follow the editor to study!

1. Send email in the simplest version of spring boot

Spring boot email is quite simple, first of all, add the email start to the pom:

Org.springframework.boot spring-boot-starter-mail

Then configure the parameters for sending e-mail in application.properties

Spring.mail.host=smtp.163.comspring.mail.port=25spring.mail.username=yourmail@163.comspring.mail.password=yourpassword

There is an one-to-one correspondence between spring.mail.host and spring.mail.username, and the smtp server should be used wherever the mailbox is located.

Then I wrote a controller to receive the contents of the message board:

@ Value ("${spring.mail.username}") private String fromMail; @ Autowired private JavaMailSender mailSender; @ RequestMapping (value = "/ getNote", method = RequestMethod.POST) public String getNote (Note note) {MimeMessage mimeMessage = mailSender.createMimeMessage (); MimeMessageHelper helper; try {helper = new MimeMessageHelper (mimeMessage, true) / / sender helper.setFrom (fromMail,note.yourName); / / recipient (email address to which the message was finally sent) helper.setTo ("recieve@mail.com"); / / title helper.setSubject (note.yourSubject) / / text helper.setText ("from email:" + note.yourEmail+ "\ n" + note.yourMessage); mailSender.send (mimeMessage);} catch (MessagingException | UnsupportedEncodingException e) {/ / TODO Auto-generated catch block e.printStackTrace () } return "redirect:return.htm";} public class Note {String yourName; String yourEmail; String yourSubject; String yourMessage;//getter,setter ellipsis}

The note object is the content of the message board

JavaMailSender and MimeMessageHelper are officially recommended as good friends and are generally used together.

FromMail is the spring.mail.username property configured in application.properties, that is, the sender, using helper.setTo (...) Configuration

By the way, because I usually leave an email address when filling in the message board, but that email address has nothing to do with any place where the email is set up here. I just need to make a note in the text of the email. I was mentally retarded before and filled in the email address in helper.setTo (.). As a result, I wasted half an hour checking this kind of bug. It's a long story.

2. Send email with authorization code

In many cases, the following error occurs when you send an email according to the above method:

Javax.mail.AuthenticationFailedException: 535 Error: authentication failed

One of the reasons is that the mail server uses the authorization code login method, that is, third-party login cannot directly use the account password. Instead, you need to use an authorization code, such as the 163.com mailbox above, to set the authorization code login. The configuration interface is as follows:

QQ Mail needs to log in with the authorization code by default. QQ Mail's authorization login operation document can be found here.

After logging in with the authorization code, you need to change the content of the spring.mail.password in the application.properties from the password to the authorization code, and you can send email normally.

3. Simply talk about JavaMailSender and MimeMessageHelper.

If we look at the code of JavaMailSender, we can see that its background is actually quite complex. First, it inherits the org.springframework.mail.MailSender interface.

Public interface JavaMailSender extends MailSender {...}

And it is also an interface, and there is only one implementation class, JavaMailSenderImpl.

Let's go through the code of JavaMailSenderImpl and find that spring does not do the function of sending mail on its own, but directly uses the function of sending mail of java itself. The core is this paragraph.

Protected void doSend (MimeMessage [] mimeMessages, @ Nullable Object [] originalMessages) throws MailException {Map failedMessages = new LinkedHashMap (); Transport transport = null; try {for (int I = 0; I < mimeMessages.length; iTunes +) {/ / Check transport connection first... If (transport = = null | |! transport.isConnected ()) {if (transport! = null) {try {transport.close () } catch (Exception ex) {/ / Ignore-we're reconnecting anyway} Transport = null } try {transport = connectTransport () } catch (AuthenticationFailedException ex) {throw new MailAuthenticationException (ex) } catch (Exception ex) {/ / Effectively, all remaining messages failed... For (int j = I; j < mimeMessages.length; jacks +) {Object original = (originalMessages! = null? OriginalMessages [j]: mimeMessages [j]); failedMessages.put (original, ex);} throw new MailSendException ("Mail server connection failed", ex, failedMessages) }} / / Send message via current transport... MimeMessage mimeMessage = mimeMessages [I]; try {if (mimeMessage.getSentDate () = = null) {mimeMessage.setSentDate (new Date ()) } String messageId = mimeMessage.getMessageID (); mimeMessage.saveChanges () If (messageId! = null) {/ / Preserve explicitly specified message id... MimeMessage.setHeader (HEADER_MESSAGE_ID, messageId);} Address [] addresses = mimeMessage.getAllRecipients (); transport.sendMessage (mimeMessage, (addresses! = null? Addresses: new Address [0]);} catch (Exception ex) {Object original = (originalMessages! = null? OriginalMessages [I]: mimeMessage); failedMessages.put (original, ex) } finally {try {if (transport! = null) {transport.close () }} catch (Exception ex) {if (! failedMessages.isEmpty ()) {throw new MailSendException ("Failed to close server connection after message failures", ex FailedMessages) } else {throw new MailSendException ("Failed to close server connection after message sending", ex) }} if (! failedMessages.isEmpty ()) {throw new MailSendException (failedMessages);}}

The core class called in the doSend method is the Transport class, whose package name is javax.mail. Spring is worthy of the integration master, the mail function of java has become a part of spring's own function through the standardized packaging of spring, and then through the packaging of spring boot, it is simplified again with the way of starter, and we can use it directly in a minimalist way.

Of course, there are many ways to simplify, and another form of wrapper is to use the methods of the helper class, and spring uses MimeMessageHelper. In the way javax.mail handles email, it uses a divide-and-conquer approach, and different classes deal with different problems, so you can see a lot of classes dealing with a variety of problems and situations.

This approach is very good in the implementation of the function, decomposing a complex problem into a number of small problems, respectively. However, it is not friendly to the developers who use it, and is prone to the following problems:

It's not intuitive. The caller doesn't know where to start.

Looking for trouble, there are too many classes and functions are scattered, so it is not easy to find the corresponding functional classes.

The relationship is complex, and you are often unsure which class to refer to, because there are too many classes that deal with a single problem

Without a unified entrance, it is difficult to get started, and it is difficult to use it directly without documents.

In view of the above, spring concentrates almost all the problems that need to be dealt with in sending mail into this class through MimeMessageHelper, which is easy to use and easy to find. Here are all the methods of this class.

At this point, the study on "how to use spring boot to send email" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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