(四) 发送E-mail-白红宇

(四) 发送E-mail

阅读量：4048 次

发布时间：2019-05-25

本文共 5809 字，大约阅读时间需要 19 分钟。

为了发送E-mail，必须建立一个到端口25(即SMTP端口)的套接字连接。简单邮件传输协议用于描述E-mail消息的格式。

可以连接到任何一个提供SMTP服务的服务器，不过需要确定服务器是否愿意接受请求。SMTP服务器通常总是愿意发送来自任何人的E-mail，但是由于垃圾邮件泛滥，大多数服务器都内置有检查功能，它们只接受那些来自它们所信任的用户或IP地址段的请求。

一旦连接到服务器，就可以发送一个邮件报头(采用SMTP格式)。紧随其后是邮件消息。

操作的详细过程:

1.打开一个到达主机的套接字:

Socket socket = new Socket("mail.mailserver.com", 25);    PrintWriter out = new PrintWriter(socket.getOutputStream());

2.发送以下信息到输出流

HELO sending host

MAIL FROM: <sender e-mail address>

RCPT TO: <recipient e-mail address>

DATA

mail message

(any number of lines)

QUIT

e.g.

OutputStream outStream = socket.getOutputStream();    PrintWriter out = new PrintWriter(new OutputStreamWriter(outStream, "utf-8"), true);    String hostName = InetAddress.getLocalHost().getHostName();    out.print("HELO " + hostName + "\r\n");    out.print("MAIL FROM: <" + from.getText() + ">\r\n");    out.print("RCPT TO: <" + to.getText() + ">\r\n");    out.print("DATA\r\n");    out.print(("the mail message...\n").replaceAll("\n", "\r\n"));    out.print(".\r\n");    out.print("QUIT\r\n"));

3.SMTP规范(RFC 821)规定，每行都要以\r再紧跟一个\n来结尾。

4.有些SMTP服务器并不检查信息的真实性，可以随意填写任何喜欢使用的发件人名字。

5.现在大多数SMTP服务器都会检查守信IP，其他服务器将使用"SMTP之前先POP"规范，即要求在发送任何消息之前先下载你的E-mail，即要求提供密码。

DEMO

import java.awt.EventQueue;import javax.swing.JFrame;public class MailTest {	public static void main(String[] args) {		EventQueue.invokeLater(new Runnable(){			public void run(){				JFrame frame = new MailTestFrame();				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);				frame.setVisible(true);			}		});	}}

/** * 该程序会因为受限于SMTP服务器检测IP地址的原因，导致失败 */import java.awt.GridBagLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.net.InetAddress;import java.net.InetSocketAddress;import java.net.Socket;import java.util.Scanner;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.JTextArea;import javax.swing.JTextField;import javax.swing.SwingWorker;public class MailTestFrame extends JFrame {		private Scanner in;	private PrintWriter out;	private JTextField from;	private JTextField to;	private JTextField smtpServer;	private JTextArea message;	private JTextArea comm;		public static final int DEFAULT_WIDTH = 300;	public static final int DEFAULT_HEIGHT = 300;		public MailTestFrame(){		setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);		setTitle("MailTest");				setLayout(new GridBagLayout());				add(new JLabel("From:"), new GBC(0,0).setFill(GBC.HORIZONTAL));				from = new JTextField(20);		add(from, new GBC(1, 0).setFill(GBC.HORIZONTAL).setWeight(100, 0));				add(new JLabel("TO:"), new GBC(0, 1).setFill(GBC.HORIZONTAL));				to = new JTextField(20);		add(to, new GBC(1, 1).setFill(GBC.HORIZONTAL).setWeight(100, 0));				add(new JLabel("SMTP server:"), new GBC(0, 2).setFill(GBC.HORIZONTAL));				smtpServer = new JTextField(20);		add(smtpServer, new GBC(1, 2).setFill(GBC.HORIZONTAL).setWeight(100, 0));				message = new JTextArea();		add(new JScrollPane(message), new GBC(0, 3, 2, 1).setFill(GBC.BOTH).setWeight(100, 100));				comm = new JTextArea();		add(new JScrollPane(comm), new GBC(0, 4, 2, 1).setFill(GBC.BOTH).setWeight(100, 100));				JPanel buttonPanel = new JPanel();		add(buttonPanel, new GBC(0, 5, 2, 1));				JButton sendButton = new JButton("Send");		buttonPanel.add(sendButton);		sendButton.addActionListener(new ActionListener(){			@Override			public void actionPerformed(ActionEvent e) {				new SwingWorker
   
    (){					protected Void doInBackground() throws Exception{						comm.setText("");						sendMail();						return null;					}				}.execute();			}					});	}		public void sendMail(){		try{//			Socket socket = new Socket(smtpServer.getText(), 25);			Socket socket = new Socket();			socket.connect(new InetSocketAddress(smtpServer.getText(), 25), 2000);			try{				InputStream inStream = socket.getInputStream();				OutputStream outStream = socket.getOutputStream();								in = new Scanner(inStream);				out = new PrintWriter(new OutputStreamWriter(outStream, "utf-8"), true);								String hostName = InetAddress.getLocalHost().getHostName();								receive();				send("HELO " + hostName);				receive();				send("MAIL FROM: <" + from.getText() + ">");				receive();				send("RCPT TO: <" + to.getText() + ">");				receive();				send("DATA");				receive();				send(message.getText());				send(".");				receive();			}finally{				socket.close();			}		}catch(IOException e){			comm.append("Error: " + e);		}	}	private void send(String str) throws IOException{		comm.append(str);		comm.append("\n");		out.print(str.replaceAll("\n", "\r\n"));		out.flush();	}	private void receive() {		String line = in.nextLine();		comm.append(line);		comm.append("\n");	}}

import java.awt.GridBagConstraints;import java.awt.Insets;public class GBC extends GridBagConstraints{		public GBC(int gridx, int gridy){		this.gridx = gridx;		this.gridy = gridy;	}		public GBC(int gridx, int gridy, int gridwidth, int gridheight){		this.gridx = gridx;		this.gridy = gridy;		this.gridwidth = gridwidth;		this.gridheight = gridheight;	}		public GBC setAnchor(int anchor){		this.anchor = anchor;		return this;	}		public GBC setFill(int fill){		this.fill = fill;		return this;	}		public GBC setWeight(double weightx, double weighty){		this.weightx = weightx;		this.weighty = weighty;		return this;	}		public GBC setInsets(int distance){		this.insets = new Insets(distance, distance, distance, distance);		return this;	}		public GBC setInsets(int top, int left, int bottom, int right){		this.insets = new Insets(top, left, bottom, right);		return this;	}		public GBC setIpad(int ipadx, int ipady){		this.ipadx = ipadx;		this.ipady = ipady;		return this;	}}

转载地址：http://xayci.baihongyu.com/

你可能感兴趣的文章