郵件編程——Java

一、提前準備：

1.1準備第三方庫依賴javax.mail

	<!-- https://mvnrepository.com/artifact/javax.mail/javax.mail-api -->
	<dependency>
    	<groupId>com.sun.mail</groupId>
        <artifactId>javax.mail</artifactId>
        <version>1.6.2</version>
    </dependency>

1.2打開自己郵箱的pop3/stmp服務，並且設定相應的授權。

 二、讀取郵箱裏面的信息：

方法步驟：

1.建立郵件會話、2.建立郵件存儲空間、3.連接到郵件服務器、4.打開郵件服務器中的制定文件夾

package tools;

import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
import java.util.*;

public class MailClientRecv {
  private Session session;
  private Store store;
  private String username = "[email protected]";//郵箱賬號
  private String password = "xxxxx";//郵箱授權密碼
  private String popServer = "xxxxxxx";//郵件pop3服務器
  
  public void init()throws Exception
  {
    //設置屬性
    Properties  props = new Properties();
    props.put("mail.store.protocol", "pop3");
    props.put("mail.imap.class", "com.sun.mail.imap.IMAPStore");
    props.put("mail.pop3.class", "com.sun.mail.pop3.POP3Store");    

    // 創建Session對象
    session = Session.getInstance(props,null);
    session.setDebug(false); //輸出跟蹤日誌

    // 創建Store對象
    store = session.getStore("pop3");
    
    //連接到收郵件服務器
    store.connect(popServer,username,password);
  }  
  
  public void receiveMessage()throws Exception
  {
	String folderName = "inbox";//獲取收件箱郵件
    Folder folder=store.getFolder(folderName);
    if(folder==null)
    {
    	throw new Exception(folderName+"郵件夾不存在");
    }
    //打開信箱
    folder.open(Folder.READ_ONLY);
    System.out.println("您的收件箱有"+folder.getMessageCount()+"封郵件.");
    System.out.println("您的收件箱有"+folder.getUnreadMessageCount()+"封未讀的郵件.");

    //讀郵件
    Message[] messages=folder.getMessages();
    //for(int i=1;i<=messages.length;i++)
    for(int i=1;i<=3;i++)  
    {
      System.out.println("------第"+i+"封郵件-------");
      //打印郵件信息
      Message message = messages[i];
      //folder.getMessage(i).writeTo(System.out);
      System.out.println((message.getFrom())[0]);//發件人
      System.out.println(message.getSubject());//標題
      System.out.println();
    }
    folder.close(false);  //關閉郵件夾
  }
  
  public void close()throws Exception
  {
	store.close();
  }
  
  public static void main(String[] args)throws Exception {
    MailClientRecv client=new MailClientRecv();
    //初始化
    client.init();
    //接收郵件
    client.receiveMessage();
    //關閉連接
    client.close();
  }
}

三、發送郵件

方法步驟

1.建立郵件會話，驗證賬號並且創建、2。創建發送協議、3.發送郵件

package tools;

import javax.mail.*;
import java.util.*;
import messages.*;


public class MailClientSend {
  private Session session;
  private Transport transport;
  private String username = "xxxxxxxxx";//發件郵箱賬號
  private String password = "xxxxx";//發件郵箱密碼
  private String smtpServer = "xxxxxxxx";//郵箱的stmp服務器
  
  public void init()throws Exception
  {
	//設置屬性
    Properties  props = new Properties();
    props.put("mail.transport.protocol", "smtp");
    props.put("mail.smtp.class", "com.sun.mail.smtp.SMTPTransport");
    props.put("mail.smtp.host", smtpServer); //設置發送郵件服務器
    props.put("mail.smtp.port", "25");
    props.put("mail.smtp.auth", "true"); //SMTP服務器需要身份驗證    

    // 創建Session對象
    session = Session.getInstance(props,new Authenticator(){   //驗賬賬戶 
        public PasswordAuthentication getPasswordAuthentication() { 
          return new PasswordAuthentication(username, password); 
        }            
 });
    session.setDebug(true); //輸出跟蹤日誌
    
    // 創建Transport對象
    transport = session.getTransport();           
  }
  
  public void sendMessage()throws Exception{
    //創建一個郵件
    //Message msg = TextMessage.generate();
	//Message msg = HtmlMessage.generate();
	Message msg = AttachmentMessage.generate();
    //發送郵件    
    transport.connect();
    transport.sendMessage(msg, msg.getAllRecipients());
    //打印結果
    System.out.println("郵件已經成功發送");
  } 
  
  public void close()throws Exception
  {
	transport.close();
  }
  
  public static void main(String[] args)throws Exception {
	  
    MailClientSend client=new MailClientSend();
    //初始化
    client.init();
    //發送郵件
    client.sendMessage();
    //關閉連接
    client.close();
  }
}

3.1發送文本郵件：

package messages;

import java.util.Date;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.io.FileOutputStream;

public class TextMessage {
	public static MimeMessage generate() throws Exception {
		String from = "xxxxx "; // 發件人地址
		String to = "xxxxxx"; // 收件人地址
		
		String subject = "test";
		String body = "您好,這是來自一封chenliangyu的測試郵件";

		// 創建Session實例對象
		Session session = Session.getDefaultInstance(new Properties());
		// 創建MimeMessage實例對象
		MimeMessage message = new MimeMessage(session);
		// 設置發件人
		message.setFrom(new InternetAddress(from));
		// 設置收件人
		message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
		// 設置發送日期
		message.setSentDate(new Date());
		// 設置郵件主題
		message.setSubject(subject);
		// 設置純文本內容的郵件正文
		message.setText(body);
		// 保存並生成最終的郵件內容
		message.saveChanges();

		// 把MimeMessage對象中的內容寫入到文件中
		//msg.writeTo(new FileOutputStream("e:/test.eml"));
		return message;
	}
}

3.2發送網頁郵件：

package messages;

import java.util.Date;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.io.FileOutputStream;

public class HtmlMessage {
	public static MimeMessage generate() throws Exception 
	{
		String from = "xxxx "; // 發件人地址
		String to = "xxxxxxxx"; // 收件人地址
		
		String subject = "HTML郵件";
		String body = "<a href=http://www.ecnu.edu.cn>" 
		  + "<h4>歡迎大家訪問我們的網站</h4></a></br>" 
		  + "<img src=\"https://news.ecnu.edu.cn/_upload/article/images/2e/e2/6b554d034c9192101208c732195e/16a6ec66-6729-4469-a5f4-0435e0f2e66a.jpg\">";

		// 創建Session實例對象
		Session session = Session.getDefaultInstance(new Properties());
		// 創建MimeMessage實例對象
		MimeMessage message = new MimeMessage(session);
		// 設置發件人
		message.setFrom(new InternetAddress(from));
		// 設置收件人
		message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
		// 設置發送日期
		message.setSentDate(new Date());
		// 設置郵件主題
		message.setSubject(subject);
		// 設置HTML格式的郵件正文
		message.setContent(body, "text/html;charset=gb2312");
		// 保存並生成最終的郵件內容
		message.saveChanges();

		// 把MimeMessage對象中的內容寫入到文件中
		//msg.writeTo(new FileOutputStream("e:/HtmlMessage.eml"));
		return message;
	}
}

3.3發送附件郵件：

package messages;

import java.io.FileOutputStream;
import java.util.Properties;
import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
public class AttachmentMessage 
{
	public static MimeMessage generate() throws Exception
	{
		String from = "xxxxxx "; // 發件人地址
		String to = "xxxxxxxx"; // 收件人地址
		
        String subject = "多附件郵件";        //郵件主題
        String body = "<a href=http://www.ecnu.edu.cn>" +
        			  "歡迎大家訪問我們的網站</a></br>"; 
      
        // 創建Session實例對象
        Session session = Session.getDefaultInstance(new Properties());
     	// 創建MimeMessage實例對象
     	MimeMessage message = new MimeMessage(session);            
        message.setFrom(new InternetAddress(from));
        message.setRecipients(Message.RecipientType.TO,
        		InternetAddress.parse(to));
        message.setSubject(subject);
        
        //創建代表郵件正文和附件的各個MimeBodyPart對象
        MimeBodyPart contentPart = createContent(body);
        MimeBodyPart attachPart1 = createAttachment("c:/temp/ecnu4.jpg");
        MimeBodyPart attachPart2 = createAttachment("c:/temp/ecnu5.jpg");
        
        //創建用於組合郵件正文和附件的MimeMultipart對象
        MimeMultipart allMultipart = new MimeMultipart("mixed");
        allMultipart.addBodyPart(contentPart);
        allMultipart.addBodyPart(attachPart1);
        allMultipart.addBodyPart(attachPart2);
        
        //設置整個郵件內容爲最終組合出的MimeMultipart對象
        message.setContent(allMultipart);
        message.saveChanges();
        
        //message.writeTo(new FileOutputStream("e:/ComplexMessage.eml"));
        return message;
	}
	
	public static MimeBodyPart createContent(String body) throws Exception
	{
        MimeBodyPart htmlBodyPart = new MimeBodyPart();          
        htmlBodyPart.setContent(body,"text/html;charset=gb2312");
        return htmlBodyPart;
	}
	
	public static MimeBodyPart createAttachment(String filename) throws Exception
	{
		//創建保存附件的MimeBodyPart對象，並加入附件內容和相應信息
		MimeBodyPart attachPart = new MimeBodyPart();
        FileDataSource fds = new FileDataSource(filename);
        attachPart.setDataHandler(new DataHandler(fds));
        attachPart.setFileName(fds.getName());
		return attachPart;
	}
}

參考中國大學mooc《Java核心技術》