多樣化郵件功能實戰指南，你學會了嗎？

前言

在當今數位化的時代，郵件作為一種重要的通訊方式，廣泛應用於各類系統。無論是系統通知、使用者交互，還是檔案傳輸等場景，郵件都發揮著不可或缺的作用。

本文將探討如何實現文字、附件、HTML、圖片類型郵件的發送，並在此基礎上增加一些實用功能，如大量發送郵件、動態郵件模板渲染等，助力開發者打造更強大的郵件服務。

實現

依賴引入

<dependencies>
    <!-- Spring Boot Web支持，用于后续可能的Web接口开发 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- Spring Boot邮件启动器 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-mail</artifactId>
    </dependency>
    <!-- JavaMail API -->
    <dependency>
        <groupId>com.sun.mail</groupId>
        <artifactId>javax.mail</artifactId>
    </dependency>
    <!-- Thymeleaf模板引擎，用于邮件模板渲染 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <!-- 测试依赖 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <!-- Lombok简化代码编写 -->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>1.
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配置資訊

spring:
  mail:
    host: smtp.163.com
    port: 465
    username: your_email@163.com
    password: your_password
    properties:
      mail:
        debug: true
        smtp:
          auth: true
          starttls.enable: true
          socketFactoryClass: javax.net.ssl.SSLSocketFactory
    default-encoding: UTF-8
    protocol: smtps
  thymeleaf:
    prefix: classpath:/templates/
    suffix: .html
    cache: false


from:
  mail:
    address: your_email@163.com1.
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請將your_email@163.com替換為實際的郵件地址，your_password替換為郵箱的授權碼（非登入密碼）。若使用其他郵件伺服器，需相應修改spring.mail.host等設定。

核心程式碼

public interface MailService {
    void sendSimpleMail(String to, String subject, String content);
    void sendHtmlMail(String to, String subject, String content);
    void sendAttachmentsMail(String to, String subject, String content, String filePath);
    void sendInlineResourceMail(String to, String subject, String content, String rscPath, String rscId);
    void sendBatchSimpleMail(String[] tos, String subject, String content);
    void sendDynamicTemplateMail(String to, String subject, String templateName, Object model);
}1.
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實作類別

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.FileSystemResource;
import org.springframework.mail.SimpleMailMessage;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.stereotype.Service;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.Context;
import org.yian.service.MailService;

import javax.annotation.Resource;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import java.io.File;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;


@Service
@Slf4j
public class MailServiceImpl implements MailService {
    @Resource
    private JavaMailSender mailSender;
    @Resource
    private TemplateEngine templateEngine;
    @Value("${from.mail.address}")
    private String from;

    @Override
    public void sendSimpleMail(String to, String subject, String content) {
        SimpleMailMessage message = new SimpleMailMessage();
        message.setFrom(from);
        message.setTo(to);
        message.setSubject(subject);
        message.setText(content);
        try {
            mailSender.send(message);
            log.info("文本邮件已经发送");
        } catch (Exception e) {
            log.error("发生发送文本邮件错误！", e);
        }
    }

    @Override
    public void sendHtmlMail(String to, String subject, String content) {
        MimeMessage message = mailSender.createMimeMessage();
        try {
            MimeMessageHelper helper = new MimeMessageHelper(message, true);
            helper.setFrom(from);
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(content, true);
            mailSender.send(message);
            log.info("html邮件发送成功");
        } catch (MessagingException e) {
            log.error("发生发送html邮件错误！", e);
        }
    }

    @Override
    public void sendAttachmentsMail(String to, String subject, String content, String filePath) {
        MimeMessage message = mailSender.createMimeMessage();
        try {
            MimeMessageHelper helper = new MimeMessageHelper(message, true);
            helper.setFrom(from);
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(content, true);
            FileSystemResource file = new FileSystemResource(new File(filePath));
            String fileName = filePath.substring(filePath.lastIndexOf(File.separator));
            helper.addAttachment(fileName, file);
            mailSender.send(message);
            log.info("带附件的邮件已经发送");
        } catch (MessagingException e) {
            log.error("发生发送带附件邮件错误！", e);
        }
    }

    @Override
    public void sendInlineResourceMail(String to, String subject, String content, String rscPath, String rscId) {
        MimeMessage message = mailSender.createMimeMessage();
        try {
            MimeMessageHelper helper = new MimeMessageHelper(message, true);
            helper.setFrom(from);
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(content, true);
            FileSystemResource res = new FileSystemResource(new File(rscPath));
            helper.addInline(rscId, res);
            mailSender.send(message);
            log.info("嵌入静态图片的邮件已经发送");
        } catch (MessagingException e) {
            log.error("发生发送嵌入静态图片邮件错误！", e);
        }
    }

    @Override
    public void sendBatchSimpleMail(String[] tos, String subject, String content) {
        for (String to : tos) {
            sendSimpleMail(to, subject, content);
        }
        log.info("批量文本邮件已发送完成");
    }

    @Override
    public void sendDynamicTemplateMail(String to, String subject, String templateName, Object model) {
        Context context = new Context();
        if (model instanceof Map) {
            context.setVariables((Map<String, Object>) model);
        } elseif (model != null) {
            Map<String, Object> map = new HashMap<>();
            Field[] fields = model.getClass().getDeclaredFields();
            for (Field field : fields) {
                field.setAccessible(true);
                try {
                    map.put(field.getName(), field.get(model));
                } catch (IllegalAccessException e) {
                    log.error("转换对象为Map时出错", e);
                }
            }
            context.setVariables(map);
        }
        String emailContent = templateEngine.process(templateName, context);
        sendHtmlMail(to, subject, emailContent);
        log.info("动态模板邮件已发送");
    }
}1.
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在 src/main/resources/templates 目錄下建立 userInfoTemplate.html 檔案（Thymeleaf 預設會從該目錄載入範本），範例內容如下：

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>用户信息模板</title>
</head>
<body>
    <h1>用户信息</h1>
    <p>姓名：<span th:text="${name}"></span></p>
    <p>年龄：<span th:text="${age}"></span></p>
</body>
</html>1.
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單元測試

import cn.example.mail.service.MailService;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class MailBootTest {
    @Autowired
    private MailService mailService;

    @Test
    public void testSimpleMail() {
        mailService.sendSimpleMail("test@example.com", "测试简单文本邮件", "这是一封简单的文本邮件");
    }

    @Test
    public void testHtmlMail() {
        String content = "<html><body><h2>hello! 这是一封html邮件!</h2></body></html>";
        mailService.sendHtmlMail("test@example.com", "这是html邮件", content);
    }

    @Test
    public void sendAttachmentsMail() {
        String filePath = "C:\\example\\attachment.pdf";
        mailService.sendAttachmentsMail("test@example.com", "主题：带附件的邮件", "有附件，请查收！", filePath);
    }

    @Test
    public void sendInlineResourceMail() {
        String rscId = "exampleImage";
        String content = "<html><body>这是有图片的邮件：<img src='cid:" + rscId + "'></body></html>";
        String imgPath = "C:\\example\\image.jpg";
        mailService.sendInlineResourceMail("test@example.com", "主题：这是有图片的邮件", content, imgPath, rscId);
    }

    @Test
    public void sendBatchSimpleMail() {
        String[] tos = {"test1@example.com", "test2@example.com"};
        mailService.sendBatchSimpleMail(tos, "批量测试邮件", "这是批量发送的文本邮件");
    }

    @Test
    public void sendDynamicTemplateMail() {
        User user = new User("一安", 25);
        mailService.sendDynamicTemplateMail("test@example.com", "动态模板邮件测试", "userInfoTemplate", user);
    }

    // 测试用的用户类
    private static class User {
        private String name;
        private int age;

        public User(String name, int age) {
            this.name = name;
            this.age = age;
        }

        // 省略getter和setter方法
    }
}1.
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總結

在實際專案中，也可以進一步拓展郵件服務的功能，例如：

非同步發送郵件：使用 Spring 的非同步任務機制，將郵件發送任務非同步化，避免阻塞主線程，提高系統效能和回應速度。
郵件發送狀態追蹤：透過郵件伺服器的回饋或自訂的追蹤機制，記錄郵件的發送狀態（如發送成功、失敗、已讀等），方便系統進行後續處理。

NEWS

多樣化郵件功能實戰指南，你學會了嗎？

前言

實現

依賴引入

配置資訊

核心程式碼

實作類別

單元測試

總結

必修課：VLAN 太重要了！分享兩種最常見場景下的 VLAN 規劃配置實例！

如何幹翻你的網路？當然用它！不走尋常路的運維神器Clumsy

Hong Kong

Philippines

NEWS

多樣化郵件功能實戰指南，你學會了嗎？

前言

實現

依賴引入

配置資訊

核心程式碼

實作類別

單元測試

總結

必修課：VLAN 太重要了！ 分享兩種最常見場景下的 VLAN 規劃配置實例！

如何幹翻你的網路？當然用它！不走尋常路的運維神器Clumsy

必修課：VLAN 太重要了！分享兩種最常見場景下的 VLAN 規劃配置實例！