Java实现邮件发送（包含发送附件及图片）

在项目开发中，除了需要短信验证外，有时候为了节省 短信费也会使用邮件发送。下面一起来看看Spring Boot如何发送邮件。

本文以163邮箱为例进行邮件发送功能，需要把用户信息以附件的形式发送，其他邮箱的配置也都大同小异。

一、邮件服务器与传输协议

要在网络上实现邮件功能，必须要有专门的邮件服务器。这些邮件服务器类似于现实生活中的邮局，它主要负责接收用户投递过来的邮件，并把邮件投递到邮件接收者的电子邮箱中。
SMTP服务器地址：一般是 smtp.xxx.com，比如163邮箱是smtp.163.com，qq邮箱是smtp.qq.com。
SMTP协议：通常把处理用户smtp请求(邮件发送请求)的服务器称之为SMTP服务器(邮件发送服务器)。
POP3协议：通常把处理用户pop3请求(邮件接收请求)的服务器称之为POP3服务器(邮件接收服务器)。

二、Java发送邮件

2.1获取授权码

网易邮箱–>设置–>QQ邮箱–>邮箱设置–>账户–>POP3/SMTP/IMAP

开启POP3/SMTP服务，然后获取16位授权码（注意不要将授权码泄露，一个账户可以拥有多个授权码）

 2.2添加依赖

        <!--excel依赖-->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>5.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>5.0.0</version>
        </dependency>
        <!--easyexcel-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>3.1.1</version>
        </dependency>
        <!--邮件依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mail</artifactId>
        </dependency>
        <!--把配置文件的信息，读取并自动封装成实体类-->
        <dependency>
            <groupId >org.springframework.boot</groupId >
            <artifactId >spring-boot-configuration-processor</artifactId >
            <optional >true</optional >
        </dependency>

2.3. 配置邮箱信息

需要注意的是password不是邮箱登录密码，而是2.1中获取的授权码。

#文件下载路径
file:
  path:
    # window配置 D:/home/mail  Linux: /home/app/mail
    mail: D:/home/mail

spring:
  mail:
    protocol: smtps
    from: xxx@163.com
    host: smtp.163.com  飞书邮箱发送时host改为smtp.feishu.cn
    username: xxxx@163.com
    password: xxxxxxxxxx
    port: 465
    properties:
      mail:
        smtp:
          auth: true
          socketFactory:
            port: 465
            class: javax.net.ssl.SSLSocketFactory
          starttls:
            enable: true
            required: true

2.4. 发送邮件

与配置文件映射的实体类

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix="spring.mail")
@Data
public class MailConfiguartion {

    private String protocol;

    private String from;

    private String host;

    private String username;

    private String password;

    private String port;
}

controller

import com.baba.mybatis.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.io.IOException;

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @RequestMapping(value = "/sendMail", method = RequestMethod.GET)
    public void sendMail() throws IOException {
        userService.sendMail();
    }
}

service

import com.baba.mybatis.entity.MailConfiguartion;
import com.baba.mybatis.entity.User;
import com.baba.mybatis.mapper.UserMapper;
import com.baba.mybatis.service.UserService;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import javax.activation.DataHandler;
import javax.activation.DataSource;
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.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.List;
import java.util.Properties;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserMapper userMapper;

    @Autowired
    private MailConfiguartion mailConfiguartion;

    @Value("${file.path.mail}")
    private String downloadFilePath;

    @Override
    public void sendMail() throws IOException {
        //查询生成excel文件所需要的数据
        List<User> userList = userMapper.queryUserInfo();
        //生成excel保存到downloadFilePath
        File file = createFile(userList);
        //to :邮件接收人
        String to = "xxxxx@qq.com";
        //发送邮件
        sendMailFile(to, file);
    }

    void sendMailFile(String to, File file) {
        // 创建邮件会话
        Properties properties = new Properties();
        properties.put("mail.transport.protocol", mailConfiguartion.getProtocol());
        properties.put("mail.smtp.host", mailConfiguartion.getHost());
        properties.put("mail.smtp.port", mailConfiguartion.getPort());
        properties.put("mail.smtp.auth", "true");
        properties.put("mail.smtp.ssl.enable", "true");
        Session session = Session.getInstance(properties, new Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(mailConfiguartion.getUsername(), mailConfiguartion.getPassword());
            }
        });
        try {
            // 创建邮件消息体
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(mailConfiguartion.getFrom()));
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setSubject("用户信息通知");
            // 创建多部分消息体
            Multipart multipart = new MimeMultipart();
            // 添加文本消息
            BodyPart messageBodyPart = new MimeBodyPart();
            StringBuffer sb=new StringBuffer();
            sb.append("这是一封测试邮件").append("\n");
            sb.append("所有用户信息见附件").append("\n");
            messageBodyPart.setText(sb+"");
            multipart.addBodyPart(messageBodyPart);
            // 添加附件
            messageBodyPart = new MimeBodyPart();
            String filename = file.getName();
            DataSource source = new FileDataSource(file);
            messageBodyPart.setDataHandler(new DataHandler(source));
            messageBodyPart.setFileName(filename);
            multipart.addBodyPart(messageBodyPart);
            // 设置整个邮件消息体
            message.setContent(multipart);
            // 发送邮件
            Transport.send(message);
            System.out.println("邮件发送成功");
        } catch (MessagingException ex) {
            ex.printStackTrace();
        }
    }

    private File createFile(List<User> userList) throws IOException {
        Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet("用户信息");
        // 创建表头行
        Row headerRow = sheet.createRow(0);
        Cell headerCell1 = headerRow.createCell(0);
        Cell headerCell2 = headerRow.createCell(1);
        Cell headerCell3 = headerRow.createCell(2);
        headerCell1.setCellValue("编号");
        headerCell2.setCellValue("姓名");
        headerCell3.setCellValue("年龄");
        for (int i = 0; i < userList.size(); i++) {
            // 创建数据行
            Row dataRow1 = sheet.createRow(i + 1);
            Cell dataCell1 = dataRow1.createCell(0);
            Cell dataCell2 = dataRow1.createCell(1);
            Cell dataCell3 = dataRow1.createCell(2);
            dataCell1.setCellValue(userList.get(i).getId());
            dataCell2.setCellValue(userList.get(i).getName());
            dataCell3.setCellValue(userList.get(i).getAge());
        }
        // 文件目录不存在则创建文件夹及文件，若存在则覆盖文件
        File file = new File(downloadFilePath + "/" + "用户信息.xlsx");
        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdirs();
            file.createNewFile();
        } else {
            file.delete();
            file.createNewFile();
        }
        FileOutputStream outputStream = new FileOutputStream(downloadFilePath + "/" + "用户信息.xlsx");
        workbook.write(outputStream);
        workbook.close();
        outputStream.close();
        return file;
    }

}

2.5. 发送效果  

正文换行sb.append("这是一封测试邮件").append("\n");

或者sb.append("这是一封测试邮件").append("<br>");