廖雪峰Java13网络编程-2Email编程-1发送email

1.邮件发送

1.1传统邮件发送：

• 传统的邮件是通过邮局投递，从一个邮局到另一个邮局，最终到达用户的邮箱。

1.2电子邮件发送：

• 与传统邮件类似，它是从用户电脑的邮件软件（如outlook）发送到邮件服务器上，然后经过若干个邮件服务器的中转，到达对方邮件服务器上，收件方就可以用软件或浏览器来接收邮件。
• MUA（邮件软件，Mail User Agent）——>MTA（邮件服务器，Mail Transfer Agent）——>MTA——>MDA（邮件投递代理，Mail Delivery Agent）<——MUA
• 邮件一半到达MDA就不再动了，等收件人通过MUA或浏览器查看邮件即可
• 从MUA发送到MTA使用的协议就是SMTP协议

1.3 SMTP协议：发送电子邮件的协议

• Simple Mail Transport protocol：SMTP是一个建立在TCP之上的协议。
• 标准端口：25
• 加密端口：465/587。如果某个会话需要被加密的话，使用加密端口465/587

2 如何发送EMail：

• 使用Java Mail API
• 无需关心SMTP协议原理。

2.1 使用Java Mail API有三个部分

#    创建session
Session session = Session.getInstance(props,new Authenticator(){...});
#    创建message对象
MimeMessage message = new MimeMessage(session);
message.setFrom(new InternetAddress("from@email.com")); //发件人
message.setRecipient(Message.RecipientType.TO, new IntenetAddress("to@email.com")); //收件人
message.setSubject("RE:how to use JavaEmail","UTF-8"); //邮件主题
message.setText("blablabla...","UTF-8"); //邮件正文
#    发送邮件
Transport.send(message);

示例代码

package com.csj2018;

import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
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 SendQQMailUtil {

    public static void main(String[] args) throws AddressException,MessagingException {
        Properties properties = new Properties();
        properties.put("mail.transport.protocol", "smtp");// 连接协议
        properties.put("mail.smtp.host", "smtp.qq.com");// 主机名  网易替换为"smtp.126.com"
        properties.put("mail.smtp.port", 465);// 端口号
        properties.put("mail.smtp.auth", "true");
        properties.put("mail.smtp.ssl.enable", "true");// 设置是否使用ssl安全连接 ---一般都使用
//        properties.put("mail.debug", "true");// 设置是否显示debug信息 true 会在控制台显示相关信息，同session.setDebug(true);
        // 得到回话对象
        Session session = Session.getInstance(properties);
        session.setDebug(true);
        // 获取邮件对象
        Message message = new MimeMessage(session);
        // 设置发件人邮箱地址
        message.setFrom(new InternetAddress("123456789@qq.com"));
        // 设置收件人邮箱地址，多个收件人
        message.setRecipients(Message.RecipientType.TO, new InternetAddress[]{new InternetAddress("123456789@qq.com"),new InternetAddress("1234567890@qq.com")}); 
        //message.setRecipient(Message.RecipientType.TO, new InternetAddress("xxx@qq.com"));//一个收件人
        // 设置邮件标题
        message.setSubject("xmqtest");
        // 设置邮件内容
        message.setText("邮件内容邮件内容邮件内容xmqtest");
        // 得到邮差对象
        Transport transport = session.getTransport();
        // 连接自己的邮箱账户
        transport.connect("123456789@qq.com", "abcdefg");// 密码为QQ邮箱开通的stmp服务后得到的客户端授权码
        // 发送邮件
        transport.sendMessage(message, message.getAllRecipients());
        transport.close();
    }
}

2.2 新建maven工程

pom.xml导入依赖

<!-- https://mvnrepository.com/artifact/javax.mail/mail -->
<dependency>
    <groupId>javax.mail</groupId>
    <artifactId>mail</artifactId>
    <version>1.4</version>
</dependency>

注意：不要导错依赖。详细请参考

        <!-- https://mvnrepository.com/artifact/javax.mail/javax.mail-api -->
        <!--导入javax.mail-api，运行时会提示Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/mail/util/MailLogger
-->
        <dependency>
            <groupId>javax.mail</groupId>
            <artifactId>javax.mail-api</artifactId>
            <version>1.6.2</version>
        </dependency>

2.3 发送一封文本邮件

package com.email;

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.security.MessageDigest;
import java.util.Properties;

public class SendMail {
    final String smtpHost;
    final String username;
    final String password;
    final boolean debug;
    public SendMail(String smtpHost,String username,String password){
        this.smtpHost = smtpHost;
        this.username = username;
        this.password = password;
        this.debug = true;
    }
    public static void main(String[] args) throws Exception{
        SendMail sender = new SendMail("smtp.qq.com","123456789@qq.com","abcdefg");
        Session session = sender.createSSLSession();
        Message message = createTextMessage(session,"123456789@qq.com","123456789@126.com","标题吗","Hello,这是一封Javamail测试邮件");
        Transport.send(message);
    }
    //创建一个加密的session对象
    private Session createSSLSession(){
        Properties props = new Properties();
        props.put("mail.transport.protocol","smtp");
        props.put("mail.smtp.host",this.smtpHost);//SMTP主机名
        props.put("mail.smtp.port",465);//主机端口号
        props.put("mail.smtp.auth","true");//是否需要用户认证
        //启动SSL
        props.put("mail.smtp.socketFactory.class","javax.net.ssl.SSLSocketFactory");
        props.put("mail.smtp.socketFactory.port","465");
        Session session = Session.getInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(SendMail.this.username,SendMail.this.password);
            }
        });
        session.setDebug(this.debug);//显示调试信息
        return session;
    }
    private static Message createTextMessage(Session session,String from,String to,String subject,String body) throws MessagingException {
        MimeMessage message= new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.setRecipient(Message.RecipientType.TO,new InternetAddress(to));
        message.setSubject(subject,"UTF-8");
        message.setText(body,"UTF-8");
        return message;
    }
}

2.4发送一个HTML格式的邮件

package com.email;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendMailWithHtml {
    public static void main(String[] args) throws Exception{
        SendMail sendMail = new SendMail("smtp.qq.com","123456789@qq.com","abcdefg");
        Session session = sendMail.createSSLSession();
        Message message = createHtmlMessage(session,"123456789@qq.com","123456789@126.com","这是一封html的邮件","
" +
                "<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
" +
                "<html xmlns="http://www.w3.org/1999/xhtml">
" +
                "
" +
                "<head>
" +
                "
" +
                "<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
" +
                "<meta http-equiv="Cache-Control" content="no-transform" />
" +
                "<title>剧烈咳嗽就是肺癌？肺癌的这些症状也不可忽视 - 家庭医生在线肿瘤频道</title>
" +
                "<meta name="keywords" content="剧烈咳嗽,肺癌,肺癌的症状" />
" +
                "<meta name="description" content="肺癌，一个发病率极其高的癌症，由于目前环境污染日渐严重，导致越来越多的人肺部受到感染而出现病变，导致肺癌的出现，生活中有很多因为肺癌而丧失性命的人。也正是因为如此让很多人对于肺癌都比较重视，对于肺癌也有做相关的了解，而大多数人因为过于谨慎，在身体出现一些成风吹草动的时候就认为是肺癌，特别是在出现剧烈咳嗽的时候，其实出现剧烈咳嗽也并不完全是肺癌发生。" />
" +
                "<script type="text/javascript">
" +
                "CUSTOMER.setCus(["channel:cancer","level:page"]);
" +
                "</script>
" +
                "</head>
" +
                "<body>
" +
                "	<div class="article-titile">
" +
                "		<h1>剧烈咳嗽就是肺癌？肺癌的这些症状也不可忽视</h1></div>
" +
                "<!--头部模块开始--> 
" +
                "<div id="viewContent" class="viewContent"> <p style="text-indent:2em;text-align:left;">肺癌，一个发病率极其高的，由于目前环境污染日渐严重，导致越来越多的人肺部受到而出现病变，导致肺癌的出现，生活中有很多因为肺癌而丧失性命的人。也正是因为如此让很多人对于肺癌都比较重视，对于肺癌也有做相关的了解，而大多数人因为过于谨慎，在身体出现一些成风吹草动的时候就认为是肺癌，特别是在出现剧烈咳嗽的时候，其实出现剧烈咳嗽也并不完全是肺癌发生。</p>
" +
                "			</div>
" +
                "</body>
" +
                "</html>");
        Transport.send(message);
    }
    static Message createHtmlMessage(Session session,String from,String to,String subject,String body) throws MessagingException{
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.setRecipient(Message.RecipientType.TO,new InternetAddress(to));
        message.setSubject(subject,"UTF-8");
        message.setText(body,"UTF-8","html");
        return message;
    }
}

### 2.5发送带附件的邮件 ```#java package com.email;

import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import java.io.;

public class SendMailWithAttachment {
public static void main(String[] args) throws Exception{
SendMail sender = new SendMail("smtp.qq.com","123456678@qq.com","abcdefghjik");
Session session = sender.createSSLSession();
//创建一个带附件的邮件
Message message = createMessageWithAttachment(session,"123456678@qq.com","红米note5图片","为什么成功了","/src/main/resources/1.jpg","123456789@qq.com","987654321@qq.com","123456789@126.com");
Transport.send(message);
File f = new File(".");
System.out.println(f.getCanonicalFile());
File nf = new File(f.getCanonicalFile()+"/src/main/resources/1.jpg");
if(nf.exists()){
System.out.println(nf+"存在");
}else{
System.out.println(nf+"不存在");
}

}
static Message createMessageWithAttachment(Session session, String from, String subject,String body, String filename, String... to) throws MessagingException,IOException {
    //本质上还是一个MimeMessage对象，但不能通过setText设置正文，需要使用MimeMultipart
    MimeMessage message = new MimeMessage(session);
    message.setFrom(new InternetAddress(from));
    for(String s:to){
        message.setRecipient(Message.RecipientType.TO,new InternetAddress(s));
    }

    message.setSubject(subject);
    //通过Multipart将内容分为2部分
    Multipart multipart = new MimeMultipart();
    //text
    BodyPart textpart = new MimeBodyPart();
    textpart.setContent(body,"text/html;charset=utf-8");//body表示邮件正文
    multipart.addBodyPart(textpart);
    //再次创建一个MimeBodyPart上传附件
    BodyPart imagePart = new MimeBodyPart();
    imagePart.setFileName(filename);
    DataHandler dh1 = new DataHandler(new FileDataSource(new File(".").getCanonicalPath()+filename));
    imagePart.setDataHandler(dh1);//如何获取附件的数据
    multipart.addBodyPart(imagePart);

    message.setContent(multipart);
    return message;
}

}

<h1 style="color:blue">使用输入流发送附件</h1>
<p style="color:red">确保图片在resource目录下</p>

```#java
package com.email;

import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.util.ByteArrayDataSource;
import java.awt.*;
import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

public class SendMailWithAttachment {
    public static void main(String[] args) throws Exception{
        SendMail sender = new SendMail("smtp.qq.com","123456789@qq.com","abcdefghjkik");
        Session session = sender.createSSLSession();
        //创建一个输入流
        try(InputStream input = SendMailWithAttachment.class.getResourceAsStream("/1.jpg")){
            //创建一个带附件的邮件
            Message message = createMessageWithAttachment(session,"123456789@qq.com","红米note5图片","为什么成功了","1.jpg",input,"123456789@qq.com","987654321@qq.com","123456789@126.com");
            Transport.send(message);
        }
    }
    static Message createMessageWithAttachment(Session session, String from, String subject,String body, String filename,InputStream input, String... to) throws MessagingException,IOException {
        //本质上还是一个MimeMessage对象，但不能通过setText设置正文，需要使用MimeMultipart
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        for(String s:to){
            message.setRecipient(Message.RecipientType.TO,new InternetAddress(s));
        }

        message.setSubject(subject);
        //通过Multipart将内容分为2部分
        Multipart multipart = new MimeMultipart();
        //text
        BodyPart textpart = new MimeBodyPart();
        textpart.setContent(body,"text/html;charset=utf-8");//body表示邮件正文
        multipart.addBodyPart(textpart);
        //再次创建一个MimeBodyPart上传附件
        BodyPart imagePart = new MimeBodyPart();
        imagePart.setFileName(filename);
        imagePart.setDataHandler(new DataHandler(new ByteArrayDataSource(input,"Application/octet-stream")));
        multipart.addBodyPart(imagePart);
        message.setContent(multipart);
        return message;
    }
}

2.6如何把附件嵌入到正文中

package com.csj2018;

import javax.activation.DataHandler;
import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.util.ByteArrayDataSource;
import java.io.InputStream;

public class SendMailWithInnerImage {
    public static void main(String[] args) throws Exception{
        SendMail sender = new SendMail("smtp.qq.com", "815379479@qq.com", "oovtbkpfvfzobdag");
        Session session = sender.createSSLSession();
        try(InputStream input = SendMailWithInnerImage.class.getResourceAsStream("/RedmiNote5-1.png")){
            Message message = createMessageWithInnerImage(session,"815379479@qq.com","chenshanju01@126.com","带图片测试","<h1><hello/h1><p><img src="cid:img01" ></p><p>这是一封带图片的测试邮件</p>","1.png",input);
            Transport.send(message);
        }
    }
    static Message createMessageWithInnerImage(Session session, String from, String to, String subject, String body, String filename, InputStream input) throws Exception{
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.setRecipient(Message.RecipientType.TO,new InternetAddress(to));
        message.setSubject(subject,"UTF-8");
        Multipart multipart = new MimeMultipart();
        BodyPart textpart = new MimeBodyPart();
        textpart.setContent(body,"text/html;charset=utf-8");
        multipart.addBodyPart(textpart);

        BodyPart imagepart = new MimeBodyPart();
        imagepart.setFileName(filename);
        imagepart.setDataHandler(new DataHandler(new ByteArrayDataSource(input,"application/x-png")));
        //对一个图片内容设置Content-ID，就可以在邮件中引用它，引用方式是<img src="cid:img01">
        imagepart.setHeader("Content-ID","<img01>");
        multipart.addBodyPart(imagepart);
        message.setContent(multipart);
        return message;
    }
}

content-type类型对应表：http://tool.oschina.net/commons/

3.总结

使用JavaMail API发送邮件本质上是一个MUA软件，类似outlook
Java发送Email：

• 用Maven引入javamail依赖
• 确定SMTP服务器信息：域名/端口/使用明文/SSL/TLS
• 调用相关API发送Email（无需关心底层TCP Socket连接）
• 设置debug模式可以查看通信详细内容