Question

我正在开展一个项目，我需要从数据库中检索电子邮件地址，然后向他们发送电子邮件。我已经在arraylist中检索了这些电子邮件地址。像这样：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import javaapplication1.Person;

public class ABC {
    public static void main(String[] args) throws SQLException {
        ArrayList<Person> personlist = new ArrayList<Person>();
        //List<Person> personlist = new List<Person>();
        try {


            Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","gsjsc","gsjschanna");
            Statement st=con.createStatement();

            ResultSet srs = st.executeQuery("SELECT * FROM person2");
            while (srs.next()) {
                Person person = new Person();
                person.setName(srs.getString("name"));
                person.setJobtitle(srs.getString("jobtitle"));
               // person.setFrequentflyer(srs.getInt("frequentflyer"));
                personlist.add(person);
            }

            System.out.println(personlist.size());
            for (int a=0;a<personlist.size();a++)
            {
            System.out.println(personlist.get(a).getName());
            System.out.println(personlist.get(a).getJobtitle());
            // System.out.println(personlist.get(2).getName());
            // System.out.println(personlist.get(3).getName());
            }
            //System.out.println(personlist.get(4));

        //System.out.println(namelist.);
        } catch (Exception e) {
            System.err.println("Got an exception! ");
            System.err.println(e.getMessage());
        }
    }
}

Person.java：包含所有setter和getter。

编辑

现在我必须向对象人员的arraylist中检索到的那些电子邮件地址发送电子邮件。我有一个代码，用于向arraylist中的多个收件人发送电子邮件，如下所示：

    package javaapplication1;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.Scanner;
import javax.mail.Address;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendEmailToGroupDemo {

 public static void main(String[] args) {

  // Create a SendEmail object and call start 
  // method to send a mail in Java.
  SendEmailToGroupDemo sendEmailToGroup = new SendEmailToGroupDemo();
  sendEmailToGroup.start();

 }

 private void start() {

  // For establishment of email client with 
  // Google's gmail use below properties.
  // For TLS Connection use below properties
  // Create a Properties object 
  Properties props = new Properties();

  // these properties are required
  // providing smtp auth property to true
  props.put("mail.smtp.auth", "true");
  // providing tls enability
  props.put("mail.smtp.starttls.enable", "true");
  // providing the smtp host i.e gmail.com
  props.put("mail.smtp.host", "smtp.gmail.com");
  // providing smtp port as 587
  props.put("mail.smtp.port", "587");

  // For SSL Connection use below properties

  /*props.put("mail.smtp.host", "smtp.gmail.com");
   props.put("mail.smtp.socketFactory.port", "465");
   props.put("mail.smtp.socketFactory.class",
     "javax.net.ssl.SSLSocketFactory");
   props.put("mail.smtp.auth", "true");
   props.put("mail.smtp.port", "465");*/

  // Create Scanner object to take necessary 
  // values from the user.
  Scanner scanner = new Scanner(System.in);

  System.out.println("Please provide your Username for Authentication ...");
  final String Username = scanner.next();

  System.out.println("Please provide your Password for Authentication ...");
  final String Password = scanner.next();

  System.out.println("Please provide Email Address from which you want to send Email ...");
  final String fromEmailAddress = scanner.next();

  System.out.println("Please provide Email Addresses to which you want to send Email ...");
  System.out.println("If you are done type : Done or done");

  // ArrayLists to store email addresses entered by user
  ArrayList< String> emails = (ArrayList< String >) getEmails();

  System.out.println("Please provide Subject for your Email ... ");
  final String subject = scanner.next();

  System.out.println("Please provide Text Message for your Email ... ");
  final String textMessage = scanner.next();

  // Create a Session object based on the properties and 
  // Authenticator object
  Session session = Session.getDefaultInstance(props, 
    new LoginAuthenticator(Username,Password));

  try {

   // Create a Message object using the session created above
   Message message = new MimeMessage(session);

   // setting email address to Message from where message is being sent
   message.setFrom(new InternetAddress(fromEmailAddress));

   // setting the email addressess to which user wants to send message 
   message.setRecipients(Message.RecipientType.BCC, getEmailsList(emails));

   // setting the subject for the email 
   message.setSubject(subject);

   // setting the text message which user wants to send to recipients
   message.setText(textMessage);

   // Using the Transport class send() method to send message 
   Transport.send(message);

   System.out.println("\nYour Message delivered successfully ....");

  } catch (MessagingException e) {

   throw new RuntimeException(e);

  }  
 }

 // This method takes a list of email addresses and 
 // returns back an array of Address by looping the 
 // list one by one and storing it into Address[]
 private Address[] getEmailsList(ArrayList< String > emails) {

  Address[] emaiAddresses = new Address[emails.size()];

  for (int i =0;i < emails.size();i++) {
   try {
    emaiAddresses[i] = new InternetAddress(emails.get(i));
   }
   catch (AddressException e) {

    e.printStackTrace();
   }
  }
  return emaiAddresses;
 }

 // This method prompts user for email group to which he
 // wants to send message
 public List< String > getEmails() {
  ArrayList< String > emails = new ArrayList< String >();

  int counter = 1;
  String address = "";
  Scanner scanner = new Scanner(System.in);

  // looping inifinitely times as long as user enters 
  // emails one by one
  // the while loop breaks when user types done and 
  // press enter.
  while(true) {

   System.out.println("Enter E-Mail : " + counter);
   address = scanner.next();

   if(address.equalsIgnoreCase("Done")){
    break;
   }
   else {
    emails.add(address);
    counter++;
   }
  }

  return emails;
 }
}

// Creating a class for Username and Password authentication
// provided by the user.
class LoginAuthenticator extends Authenticator {
 PasswordAuthentication authentication = null;

 public LoginAuthenticator(String username, String password) {
  authentication = new PasswordAuthentication(username,password);
 }

 @Override
 protected PasswordAuthentication getPasswordAuthentication() {
  return authentication;
 }
}

这是一个完全不同的代码。但是可以向一群人发送电子邮件。但问题是我们必须手动输入电子邮件地址。而我想将邮件发送到从ABC类检索到的地址。有人可以给我一个集成的代码（对于这两个类），这将是伟大的。

Answer 1

这应该转换List Person ArrayList中的String public ArrayList<String> getEmailsFromPersons(List<Person> persons) { ArrayList<String> emails = new ArrayList<String>(); for(Person person : persons) { String email = person.getEmail(); if(email != null && !email.trim().isEmpty()) { emails.add(email); } } return emails; }来自所有人的电子邮件。

{{1}}

Answer 2

我已经在arraylist中检索了这些电子邮件地址。像这样：

我没有在Person对象中看到任何电子邮件。但是仍然会尝试在编辑后从我理解的内容中回答您的问题。下面的代码应该符合您的需求（请不要在没有任何检查的情况下动态编写任何错误）：

public class ABC {
public static void main(String[] args) throws SQLException {
    ArrayList<Person> personlist = new ArrayList<Person>();
    // Creating a separate list of emails for Persons
    List<String> personEmails = new ArrayList<String>();

    //List<Person> personlist = new List<Person>();
    try {


        Class.forName("oracle.jdbc.driver.OracleDriver");
        Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:xe","gsjsc","gsjschanna");
        Statement st=con.createStatement();

        ResultSet srs = st.executeQuery("SELECT * FROM person2");
        String email = "";
        while (srs.next()) {
            Person person = new Person();
            person.setName(srs.getString("name"));
            person.setJobtitle(srs.getString("jobtitle"));
            // person.setFrequentflyer(srs.getInt("frequentflyer"));
            // I am assuming you would be setting email in person like this
            email = srs.getString("email");
            person.setEmail(email);
            // Add the email simultaneously to the separate list
            personEmails.add(email);
            personlist.add(person);
        }

        System.out.println(personlist.size());
        for (int a=0;a<personlist.size();a++)
        {
        System.out.println(personlist.get(a).getName());
        System.out.println(personlist.get(a).getJobtitle());
        // System.out.println(personlist.get(2).getName());
        // System.out.println(personlist.get(3).getName());
        }
        //System.out.println(personlist.get(4));

    //System.out.println(namelist.);
    } catch (Exception e) {
        System.err.println("Got an exception! ");
        System.err.println(e.getMessage());
    }


    // call the email sender method of yours with the newly created list
    SendEmailToGroupDemo sendEmailToGroup = new SendEmailToGroupDemo();
    // Obviously, make that start() method public having parameter of type List<String> instead of calling getEmails() within it
    sendEmailToGroup.start(personEmails); 
    // Very little remains to be done, I hope you can figure it out easily
} 
}

发送电子邮件至从数据库

2 个答案: