import javax.mail.Authenticator;
import javax.mail.PasswordAuthentication;

public class Email_Autherticator extends Authenticator {
    String username = "你邮箱的用户名";
  
    String password = "你邮箱的密码";
    public Email_Autherticator() {
  super();
    }
    public Email_Autherticator(String user,String pwd){
  super();
  username = user;
  password = pwd;
    }
    public PasswordAuthentication getPasswordAuthentication(){
  return new PasswordAuthentication(username,password);
    }
}

import java.util.Date;
import java.util.Properties;
import javax.mail.Address;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.SendFailedException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class Mail {
    private String host = "smtp.126.com";
  
    private String mail_head_name = "this is head of this mail";
  
    private String mail_head_value = "this is head of this mail";
  
    private String mail_to = "254173774@qq.com";
  
    private String mail_from = "hackboyo@126.com";
  
    private String mail_subject = "this is the subject of this test mail";
  
    private String mail_body = "this is mail_body of this test mail";
  
    private String personalName = "我的邮件";
    public void sendMail() throws SendFailedException{
  try {
      Properties props = new Properties();//获取系统环境
      Authenticator auth = new Email_Autherticator();//进行邮件服务用户认证
      props.put("mail.smtp.host", host);
      props.put("mail.smtp.auth", "true");
      System.out.println(props);
      Session session = Session.getDefaultInstance(props,auth);
      //设置session,和邮件服务器进行通讯
      MimeMessage message = new MimeMessage(session);
      message.setContent("Hello","text/plain");//设置邮件格式
      message.setSubject(mail_subject);//设置邮件主题
      message.setText(mail_body);//设置邮件内容
      message.setHeader(mail_head_name, mail_head_value);//设置邮件标题
      message.setSentDate(new Date());//设置邮件发送时期
      Address address = new InternetAddress(mail_from,personalName);
      message.setFrom(address);//设置邮件发送者的地址
      Address toaddress = new InternetAddress(mail_to);//设置邮件接收者的地址
      message.addRecipient(Message.RecipientType.TO,toaddress);
      System.out.println(message);
      Transport.send(message);
      System.out.println("Send Mail Ok!");
  } catch (Exception e) {
      e.printStackTrace();
  }
  //return flag;
    }
}

public class Test {
    public static void main(String[] args) {
  Mail m = new Mail();
  try {
      m.sendMail();
  } catch (Exception e) {
    
  }
    }
}