The application technology principles of the Javamail API JAR framework in the Java class library

Javamail API is a standard API that develops email in Java applications.It provides the function of sending, receiving and processing emails. By using the JAR framework, it can easily use the Javamail API in the Java library. The JAR framework of the Javamail API is a packing file that contains all classes, interfaces and other necessary resources of the Javamail API.Use the JAR framework to easily add the Javamail API to the Java project and use its rich features to process emails. The technical principles of using the Javamail API in the Java class library are as follows: 1. Introduce jar file: First of all, add the javamail API's jar file to the class path of the Java project.This can manage the dependencies by placing the jar file in the LIB directory of the project or using the construction tool (such as Apache Maven). 2. Import the necessary class: In the Java class, you need to import the related classes and interfaces of the Javamail API through the import statement so that they can be used in the code.For example, you can use the following sentences to import some commonly used categories of Javamail API: import javax.mail.*; import javax.mail.internet.*; import javax.activation.*; 3. Configure email session: Before sending or receiving emails using the Javamail API, you need to create an email session.Mail session is a communication channel between Javamail API and mail server.You can create email sessions by using the session class provided by the Javamail API.You can create a basic email session through the following code: Properties properties = new Properties(); properties.put("mail.smtp.host", "smtp.example.com"); Session session = Session.getDefaultInstance(properties); The default attribute provided by the Javamail API is used here, and the host name of the SMTP server is specified. 4. Create mail: After the mail session is created, you can use the Javamail API to create an email.You can use the MESSAGE class provided by the Javamail API to represent emails.You can use the following code to create a basic email: Message message = new MimeMessage(session); message.setFrom(new InternetAddress("sender@example.com")); message.setRecipient(Message.RecipientType.TO, new InternetAddress("recipient@example.com")); message.setSubject("Hello"); message.setText("This is a test email."); A message object is created here and set up the issuer, the recipient, the theme and the text. 5. Send and receive email: After the email is created, email can be sent through the Javamail API.Use the static send method of the Transport class to send emails.For example, use the following code to send emails: Transport.send(message); Similarly, you can use Javamail API to receive emails.You can use the Store class to connect to the mail server and use the Folder class to access the mail folder.For example, you can use the following code to receive emails: Store store = session.getStore("imap"); store.connect("imap.example.com", "username", "password"); Folder folder = store.getFolder("INBOX"); folder.open(Folder.READ_ONLY); Message[] messages = folder.getMessages(); Here, the IMAP protocol is connected to the mail server and open the tank folder to get the mail. The above is the technical principle of using the Javamail API JAR framework in the Java library.By using the Javamail API, developers can easily handle emails in Java applications, including sending, receiving and processing emails.