这里要注意以下要点：

readObject() 方法中的 try/catch代码块尝试捕获 ClassNotFoundException 异常。对于 JVM 可以反序列化对象，它必须是能够找到字节码的类。如果 JVM 在反序列化对象的过程中找不到该类，则抛出一个 ClassNotFoundException 异常。

注意，readObject() 方法的返回值被转化成 Employee 引用。

当对象被序列化时，属性 SSN 的值为 ，但是因为该属性是短暂的，该值没有被发送到输出流。所以反序列化后 Employee 对象的 SSN 属性为 。

// 文件名 GreetingClient.java

import java.net.*;

import java.io.*;

public class GreetingClient

{

   public static void main(String [] args)

   {

      String serverName = args[];

      int port = Integer.parseInt(args[]);

      try

      {

         System.out.println("Connecting to " + serverName

                             + " on port " + port);

         Socket client = new Socket(serverName, port);

         System.out.println("Just connected to "

                      + client.getRemoteSocketAddress());

         OutputStream outToServer = client.getOutputStream();

         DataOutputStream out =

                       new DataOutputStream(outToServer);

         out.writeUTF("Hello from "

                      + client.getLocalSocketAddress());

         InputStream inFromServer = client.getInputStream();

         DataInputStream in =

                        new DataInputStream(inFromServer);

         System.out.println("Server says " + in.readUTF());

         client.close();

      }catch(IOException e)

      {

         e.printStackTrace();

      }

   }

}

// 文件名 GreetingServer.java

import java.net.*;

import java.io.*;

public class GreetingServer extends Thread

{

   private ServerSocket serverSocket;

   public GreetingServer(int port) throws IOException

   {

      serverSocket = new ServerSocket(port);

      serverSocket.setSoTimeout();

   }

   public void run()

   {

      while(true)

      {

         try

         {

            System.out.println("Waiting for client on port " +

            serverSocket.getLocalPort() + "...");

            Socket server = serverSocket.accept();

            System.out.println("Just connected to "

                  + server.getRemoteSocketAddress());

            DataInputStream in =

                  new DataInputStream(server.getInputStream());

            System.out.println(in.readUTF());

            DataOutputStream out =

                 new DataOutputStream(server.getOutputStream());

            out.writeUTF("Thank you for connecting to "

              + server.getLocalSocketAddress() + "\nGoodbye!");

            server.close();

         }catch(SocketTimeoutException s){

            System.out.println("Socket timed out!");

            break;

         }catch(IOException e){

            e.printStackTrace();

            break;

         }

      }

   }

   public static void main(String [] args){

      int port = Integer.parseInt(args[]);

      try{

         Thread t = new GreetingServer(port);

         t.start();

      }catch(IOException e){

         e.printStackTrace();

      }

   }

}

// 文件名 SendEmail.java

import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;

public class SendEmail

{

   public static void main(String [] args)

   {

      // 收件人电子邮箱

      String to = "abcd@gmail.com";

      // 发件人电子邮箱

      String from = "web@gmail.com";

      // 指定发送邮件的主机为 localhost

      String host = "localhost";

      // 获取系统属性

      Properties properties = System.getProperties();

      // 设置邮件服务器

      properties.setProperty("mail.smtp.host", host);

      // 获取默认session对象

      Session session = Session.getDefaultInstance(properties);

      try{

         // 创建默认的 MimeMessage 对象

         MimeMessage message = new MimeMessage(session);

         // Set From: 头部头字段

         message.setFrom(new InternetAddress(from));

         // Set To: 头部头字段

         message.addRecipient(Message.RecipientType.TO,

                                  new InternetAddress(to));

         // Set Subject: 头部头字段

         message.setSubject("This is the Subject Line!");

         // 设置消息体

         message.setText("This is actual message");

         // 发送消息

         Transport.send(message);

         System.out.println("Sent message successfully....");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}

// 文件名 SendHTMLEmail.java

import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;

public class SendHTMLEmail

{

   public static void main(String [] args)

   {

      // 收件人电子邮箱

      String to = "abcd@gmail.com";

      // 发件人电子邮箱

      String from = "web@gmail.com";

      // 指定发送邮件的主机为 localhost

      String host = "localhost";

      // 获取系统属性

      Properties properties = System.getProperties();

      // 设置邮件服务器

      properties.setProperty("mail.smtp.host", host);

      // 获取默认的 Session 对象。

      Session session = Session.getDefaultInstance(properties);

      try{

         // 创建默认的 MimeMessage 对象。

         MimeMessage message = new MimeMessage(session);

         // Set From: 头部头字段

         message.setFrom(new InternetAddress(from));

         // Set To: 头部头字段

         message.addRecipient(Message.RecipientType.TO,

                                  new InternetAddress(to));

         // Set Subject: 头字段

         message.setSubject("This is the Subject Line!");

         // 发送 HTML 消息, 可以插入html标签

         message.setContent("<h1>This is actual message</h1>",

                            "text/html" );

         // 发送消息

         Transport.send(message);

         System.out.println("Sent message successfully....");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}

// 文件名 SendFileEmail.java

import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;

public class SendFileEmail

{

   public static void main(String [] args)

   {

      // 收件人电子邮箱

      String to = "abcd@gmail.com";

      // 发件人电子邮箱

      String from = "web@gmail.com";

      // 指定发送邮件的主机为 localhost

      String host = "localhost";

      // 获取系统属性

      Properties properties = System.getProperties();

      // 设置邮件服务器

      properties.setProperty("mail.smtp.host", host);

      // 获取默认的 Session 对象。

      Session session = Session.getDefaultInstance(properties);

      try{

         // 创建默认的 MimeMessage 对象。

         MimeMessage message = new MimeMessage(session);

         // Set From: 头部头字段

         message.setFrom(new InternetAddress(from));

         // Set To: 头部头字段

         message.addRecipient(Message.RecipientType.TO,

                                  new InternetAddress(to));

         // Set Subject: 头字段

         message.setSubject("This is the Subject Line!");

         // 创建消息部分

         BodyPart messageBodyPart = new MimeBodyPart();

         // 消息

         messageBodyPart.setText("This is message body");

         // 创建多重消息

         Multipart multipart = new MimeMultipart();

         // 设置文本消息部分

         multipart.addBodyPart(messageBodyPart);

         // 附件部分

         messageBodyPart = new MimeBodyPart();

         String filename = "file.txt";

         DataSource source = new FileDataSource(filename);

         messageBodyPart.setDataHandler(new DataHandler(source));

         messageBodyPart.setFileName(filename);

         multipart.addBodyPart(messageBodyPart);

         // 发送完整消息

         message.setContent(multipart );

         //   发送消息

         Transport.send(message);

         System.out.println("Sent message successfully....");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}

// 需要用户名密码邮件发送实例

//文件名 SendEmail2.java

//本实例以QQ邮箱为例，你需要在qq后台设置

import java.util.Properties;

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.InternetAddress;

import javax.mail.internet.MimeMessage;

public class SendEmail2

{

   public static void main(String [] args)

   {

      // 收件人电子邮箱

      String to = "xxx@qq.com";

      // 发件人电子邮箱

      String from = "xxx@qq.com";

      // 指定发送邮件的主机为 smtp.qq.com

      String host = "smtp.qq.com";  //QQ 邮件服务器

      // 获取系统属性

      Properties properties = System.getProperties();

      // 设置邮件服务器

      properties.setProperty("mail.smtp.host", host);

      properties.put("mail.smtp.auth", "true");

      // 获取默认session对象

      Session session = Session.getDefaultInstance(properties,new Authenticator(){

        public PasswordAuthentication getPasswordAuthentication()

        {

         return new PasswordAuthentication("xxx@qq.com", "qq邮箱密码"); //发件人邮件用户名、密码

        }

       });

      try{

         // 创建默认的 MimeMessage 对象

         MimeMessage message = new MimeMessage(session);

         // Set From: 头部头字段

         message.setFrom(new InternetAddress(from));

         // Set To: 头部头字段

         message.addRecipient(Message.RecipientType.TO,

                                  new InternetAddress(to));

         // Set Subject: 头部头字段

         message.setSubject("This is the Subject Line!");

         // 设置消息体

         message.setText("This is actual message");

         // 发送消息

         Transport.send(message);

         System.out.println("Sent message successfully....from w3cschool.cc");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}

import java.security.GeneralSecurityException;

import java.util.Properties;

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.InternetAddress;

import javax.mail.internet.MimeMessage;

import com.sun.mail.util.MailSSLSocketFactory;

public class SendEmail

{

    public static void main(String [] args) throws GeneralSecurityException

    {

        // 收件人电子邮箱

        String to = "XXXXX@qq.com";

        // 发件人电子邮箱

        String from = "XXXXXX@qq.com";

        // 指定发送邮件的主机为 smtp.qq.com

        String host = "smtp.qq.com";  //QQ 邮件服务器

        // 获取系统属性

        Properties properties = System.getProperties();

        // 设置邮件服务器

        properties.setProperty("mail.smtp.host", host);

        properties.put("mail.smtp.auth", "true");

        MailSSLSocketFactory sf = new MailSSLSocketFactory();

        sf.setTrustAllHosts(true);

        properties.put("mail.smtp.ssl.enable", "true");

        properties.put("mail.smtp.ssl.socketFactory", sf);

        // 获取默认session对象

        Session session = Session.getDefaultInstance(properties,new Authenticator(){

            public PasswordAuthentication getPasswordAuthentication()

            {

                return new PasswordAuthentication("429240967@qq.com", "授权的 QQ 邮箱密码"); //发件人邮件用户名、密码

            }

        });

        try{

            // 创建默认的 MimeMessage 对象

            MimeMessage message = new MimeMessage(session);

            // Set From: 头部头字段

            message.setFrom(new InternetAddress(from));

            // Set To: 头部头字段

            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

            // Set Subject: 头部头字段

            message.setSubject("This is the Subject Line!");

            // 设置消息体

            message.setText("This is actual message");

            // 发送消息

            Transport.send(message);

            System.out.println("Sent message successfully....from runoob.com");

        }catch (MessagingException mex) {

            mex.printStackTrace();

        }

    }

}

参考消息