使用socket发送邮件 简单实例

发送邮件使用的是smtp协议，该协议位于tcp层上， 从最基础的理论上讲使用的就是底层socket。

而smtp使用的就是socket 25端口，

利用socket读写功能向smtp服务器写入执行命令，

从最根本上讲就是向邮件smtp服务器发送指令，而smtp 协议就是一问一答的过程。这和我们在linux服务器上敲入命令是一个过程

smtp协议几个常用指令如下:

HELO

客户端为标识自己的身份而发送的命令（通常带域名）

MAIL FROM

标识邮件的发件人；以 MAIL FROM: 的形式使用。

RCPT TO

标识邮件的收件人；以 RCPT TO: 的形式使用。

DATA

客户端发送的、用于启动邮件内容传输的命令。

QUIT

终止会话。

废话少说 将如下代码执行即可，由于代码简单，并加入了一些注释，改实例使用了base64包，

import it.sauronsoftware.base64.Base64;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.OutputStreamWriter;

import java.io.PrintWriter;

import java.net.InetAddress;

import java.net.Socket;

import java.net.UnknownHostException;

import java.text.SimpleDateFormat;

import java.util.Date;

public class SMTPDemo {

public static void main(String[] args) throws IOException, UnknownHostException{

//发送邮箱

String userMail = "nihao@163.com";

//邮箱密码

String password = "*******";

//smtp服务器

String mailHost = "smtp.163.com";

//检查邮箱的有效性

checkEmailAddress(userMail);

SMTP mail = new SMTP(mailHost, userMail, password);

MailInfo mailInfo = new MailInfo();

//构造邮件信息

//发件人，

mailInfo.setFromAddress(userMail);

//收件人

mailInfo.setToAddress("nihao@163.com");

mailInfo.setSubject("欢迎你，这是邮件标题");

mailInfo.setContentType("text/html;charset=\"utf-8\"");

mailInfo.setContent("这是邮件内容");

if (mail != null){

if (mail.send(mailInfo)){

System.out.println("mail sent.");

}else {

System.out.println("Connect to SMTP server failed!");

}

}

System.out.println("Done.");

}

static void checkEmailAddress(String address){

if (address.indexOf('@') == -1)

{

System.out.println("Invalid e-mail address '" + address + "'");

System.exit(10);

}

}

}

class SMTP{

private final static int SMTP_PORT = 25;

private InetAddress mailHost;

private InetAddress ourselves;

private String userMail;

private String password;

public SMTP(String host, String userMail, String password) throws UnknownHostException{

//smtp服务器

mailHost = InetAddress.getByName(host);

ourselves = InetAddress.getLocalHost();

this.userMail = userMail;

this.password = password;

System.out.println("smtp host ： " + mailHost);

}

public boolean send(MailInfo mailInfo) throws IOException{

Socket smtpPipe;

InputStream inn;

OutputStream outt;

//构建socket端口为25为smtp端口

smtpPipe = new Socket(mailHost, SMTP_PORT);

inn = smtpPipe.getInputStream();

outt = smtpPipe.getOutputStream();

//输入流，读取服务器返回信息

BufferedReader inBR = new BufferedReader(new InputStreamReader(inn));

//输出流，发送给服务器信息

PrintWriter outPrinter = new PrintWriter(new OutputStreamWriter(outt), true);

if (inn == null || outt == null){

System.out.println("Failed to open stream to socket");

return false;

}

//读取服务器初始化信息

String initiaID = inBR.readLine();

System.out.println(initiaID);

String receiveMsg = "";

//发送stmp协议命令，所有smtp都是从 helo命令开始的，向服务器问好

outPrinter.println("HELO " + ourselves.getHostName());

outPrinter.flush();

System.out.println("HELO " + ourselves.getHostName());

//服务器返回helo命令的信息

String welcome = inBR.readLine();

System.out.println(welcome);

//发送smtp服务器用户验证

outPrinter.println("AUTH LOGIN");

outPrinter.flush();

receiveMsg = inBR.readLine();

System.out.println("login :"+receiveMsg);

if (!receiveMsg.startsWith("334")){

return false;

}

//发送用户邮件名

outPrinter.println(Base64.encode(userMail));

outPrinter.flush();

receiveMsg = inBR.readLine();

System.out.println("user :"+receiveMsg);

if (!receiveMsg.startsWith("334")){

return false;

}

//发送用户密码

outPrinter.println(Base64.encode(password));

outPrinter.flush();

//验证通过

receiveMsg = inBR.readLine();

System.out.println("password :"+receiveMsg);

if (!receiveMsg.startsWith("235")){

return false;

}

//mail from 命令 发送发件人信箱

System.out.println("MAIL FROM :<" + mailInfo.fromAddress +">");

outPrinter.println("MAIL FROM :<" + mailInfo.fromAddress +">");

outPrinter.flush();

//服务器返回接收发件人信箱信息

receiveMsg = inBR.readLine();

System.out.println("MAIL FROM sendOK " +receiveMsg);

if (!receiveMsg.startsWith("250")){

return false;

}

//收件人rcpt to命令

System.out.println("RCPT TO: <" + mailInfo.toAddress + ">");

outPrinter.println("RCPT TO: <" + mailInfo.toAddress + ">");

outPrinter.flush();

//返回服务器处理rcpt结果

receiveMsg = inBR.readLine();

System.out.println("rcpt receive:"+receiveMsg);

if (!receiveMsg.startsWith("250")){

return false;

}

//邮件主体开始，data命令之后跟的就是邮件内容

outPrinter.println("DATA");

outPrinter.flush();

receiveMsg = inBR.readLine();

System.out.println("DATA receive:"+receiveMsg);

if (!receiveMsg.startsWith("354")){

return false;

}

//邮件格式:from: 发送人, to:收件人,

//content-type:text/html;charset="utf-8"，为邮件内容编码格式,

//subject: 邮件标题

//date: 邮件日期

StringBuilder msgBody = new StringBuilder();

msgBody.append("From: <"+ mailInfo.fromAddress+ ">" + "\r\n");

msgBody.append("To: <"+ mailInfo.toAddress + ">" + "\r\n");

msgBody.append("Content-Type: "+ mailInfo.contentType + "\r\n");

msgBody.append("Subject: "+ mailInfo.subject +" \r\n");

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

String date = format.format(new Date());

msgBody.append("Date: "+date+" \r\n");

outPrinter.println(msgBody);

outPrinter.flush();

//邮件内容

outPrinter.println(mailInfo.content+ "\r\n");

outPrinter.flush();

//.点号是邮件的结束符，必须要发送

outPrinter.println("\r\n.\r\n");

outPrinter.flush();

String acceptOK = inBR.readLine();

System.out.println("send mail endmsg:"+acceptOK);

//quit命令，退出邮件链接，即端口socket链接

outPrinter.println("QUIT");

return true;

}

}

class MailInfo{

String subject;

String fromAddress;

String toAddress;

String contentType;

String content;

public String getSubject() {

return subject;

}

public void setSubject(String subject) {

this.subject = subject;

}

public String getFromAddress() {

return fromAddress;

}

public void setFromAddress(String fromAddress) {

this.fromAddress = fromAddress;

}

public String getToAddress() {

return toAddress;

}

public void setToAddress(String toAddress) {

this.toAddress = toAddress;

}

public String getContentType() {

return contentType;

}

public void setContentType(String contentType) {

this.contentType = contentType;

}

public String getContent() {

return content;

}

public void setContent(String content) {

this.content = content;

}

}