java接收邮件_Java实现邮件收发

Java实现邮件收发需要使用JavaMail API，以下是一个简单的示例代码：

1. 发送邮件

import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendMail {
    
    public static void main(String[] args) {
        String to = "recipient@example.com";
        String from = "sender@example.com";
        String host = "smtp.gmail.com";
        
        Properties properties = System.getProperties();
        properties.setProperty("mail.smtp.host", host);
        properties.setProperty("mail.smtp.port", "587");
        properties.setProperty("mail.smtp.auth", "true");
        properties.setProperty("mail.smtp.starttls.enable", "true");
        
        Session session = Session.getDefaultInstance(properties);
        
        try {
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(from));
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setSubject("Test Email");
            message.setText("This is a test email.");
            
            Transport transport = session.getTransport("smtp");
            transport.connect(host, "sender@example.com", "password");
            transport.sendMessage(message, message.getAllRecipients());
            transport.close();
            System.out.println("Email sent successfully.");
        } catch (MessagingException mex) {
            mex.printStackTrace();
        }
    }
}

2. 接收邮件

import java.util.Properties;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Store;

public class ReceiveMail {
    
    public static void main(String[] args) {
        String host = "imap.gmail.com";
        String username = "recipient@example.com";
        String password = "password";
        
        Properties properties = System.getProperties();
        properties.setProperty("mail.store.protocol", "imaps");
        properties.setProperty("mail.imap.host", host);
        properties.setProperty("mail.imap.port", "993");
        properties.setProperty("mail.imap.starttls.enable", "true");
        
        Session session = Session.getDefaultInstance(properties);
        
        try {
            Store store = session.getStore("imaps");
            store.connect(host, username, password);
            
            Folder inbox = store.getFolder("INBOX");
            inbox.open(Folder.READ_ONLY);
            
            Message[] messages = inbox.getMessages();
            System.out.println("Total messages: " + messages.length);
            
            for (int i = 0; i < messages.length; i++) {
                System.out.println("Subject: " + messages[i].getSubject());
                System.out.println("From: " + messages[i].getFrom()[0]);
                System.out.println("Text: " + messages[i].getContent().toString());
            }
            
            inbox.close(false);
            store.close();
        } catch (MessagingException mex) {
            mex.printStackTrace();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

请注意，此示例中使用的是Gmail的SMTP和IMAP服务器。如果使用其他邮件服务提供商，则需要更改主机名和端口号。另外，发送邮件需要提供发件人的邮箱地址和密码，而接收邮件需要提供收件人的邮箱地址和密码。