springboot异步发送邮件

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java发送邮件的方法网上有很多,但是大多是属于阻塞式发送,spring 提供了很方便的实现多线程方法,结合spring可以快速实现异步发送邮件.

1. 引入依赖

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mail</artifactId>
        </dependency>
        <!-- 此外还需引入springboot 核心包-->

2. 配置spring连接池
   创建配置类,实现AsyncConfigurer

@Configuration
public class AsyncTaskConfig implements AsyncConfigurer {
    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        // 线程池维护线程的最少数量
        taskExecutor.setCorePoolSize(10);
        // 线程池维护线程的最大数量 
        taskExecutor.setMaxPoolSize(50);
        // 缓存队列
        taskExecutor.setQueueCapacity(99999);
        // 对拒绝task的处理策略
        //(1) 默认的ThreadPoolExecutor.AbortPolicy   处理程序遭到拒绝将抛出运行时RejectedExecutionException;
        //(2) ThreadPoolExecutor.CallerRunsPolicy 线程调用运行该任务的 execute 本身。此策略提供简单的反馈控制机制，能够减缓新任务的提交速度
        //(3) ThreadPoolExecutor.DiscardPolicy  不能执行的任务将被删除;
        //(4) ThreadPoolExecutor.DiscardOldestPolicy  如果执行程序尚未关闭，则位于工作队列头部的任务将被删除，然后重试执行程序（如果再次失败，则重复此过程）
        taskExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        // 线程名前缀,方便排查问题
        taskExecutor.setThreadNamePrefix("order-send-thread-");
        // 注意一定要初始化
        taskExecutor.initialize();

        return taskExecutor;

    }

    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return null;
    }
}

3. 创建发送邮件工具类
   此工具类出于本人的需要编写,可根据实际需求改写

public class EmailUtils {
    // 引入javaMailSender 
    private JavaMailSender mailSender;

    public EmailUtils(JavaMailSender mailSender) {
        this.mailSender = mailSender;
    }
    // 发送简单邮件 
    public void sendSimpleMail(String from, String to, String cc, String subject, String text) {
        if(StringUtils.isBlank(to)){
            return;
        }
        SimpleMailMessage message = new SimpleMailMessage();
        message.setFrom(from);
        message.setTo(to.split(","));
        if (StringUtils.isNotBlank(cc)) {
            message.setCc(cc.split(","));
        }
        message.setSubject(subject);
        message.setText(text);

        mailSender.send(message);
    }
    // 发送带多个附件的邮件
    public void sendAttachmentMail(String from, String to, String cc, String subject, String text, List<Attachment> attachments) throws Exception {
        if(StringUtils.isBlank(to)){
            return;
        }
        MimeMessage mimeMessage = mailSender.createMimeMessage();

        MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true);
        helper.setFrom(from);
        helper.setTo(to.split(","));
        if (StringUtils.isNotBlank(cc)) {
            helper.setCc(cc.split(","));
        }
        helper.setSubject(subject);
        helper.setText(text);
        for (Attachment attachment : attachments) {
            String attachmentName = attachment.attachmentName;
            DataSource attachmentFile = attachment.attachmentFile;
            helper.addAttachment(attachmentName, attachmentFile);
        }
        mailSender.send(mimeMessage);
    }
   // 发送带单个附件的邮件
    public void sendAttachmentMail(String from, String to, String cc, String subject, String text, Attachment attachment) throws Exception {
        if (StringUtils.isBlank(to)) {
            return;
        }
        MimeMessage mimeMessage = mailSender.createMimeMessage();

        MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true);
        helper.setFrom(from);
        helper.setTo(to.split(","));
        if (StringUtils.isNotBlank(cc)) {
            helper.setCc(cc.split(","));
        }

        helper.setSubject(subject);
        helper.setText(text);
        String attachmentName = attachment.attachmentName;
        DataSource attachmentFile = attachment.attachmentFile;
        helper.addAttachment(attachmentName, attachmentFile);

        mailSender.send(mimeMessage);
    }

    public static class Attachment {
        private String attachmentName;
        private DataSource attachmentFile;

        public Attachment(String attachmentName, DataSource attachmentFile) {
            this.attachmentName = attachmentName;
            this.attachmentFile = attachmentFile;
        }
    }
}

4. 创建发送邮件service

@Service
@Slf4j
@EnableAspectJAutoProxy(exposeProxy = true)
public class OrderSendService {
    @Autowired
    private JavaMailSender mailSender;

    @Async//注意此注解,有坑
    public void asyncSendEmail(String from, String to, String cc, String subject, String text, List<OrderExcelEntity> orderList) throws Exception {
        EmailUtils emailUtils = new EmailUtils(mailSender);
        DataSource excelDataSource = generateExcelDataSource(orderList);
        EmailUtils.Attachment attachment = new EmailUtils.Attachment("XXX.xls", excelDataSource);
        emailUtils.sendAttachmentMail(from, to, cc, subject, text, attachment);
    }
}

springboot 实现发送邮件的核心方法已完成,引用时最好根据本人实际需要进行改写.
需要注意的是,当本类中非异步方法调用asyncSendEmail()时,怎么也不能实现异步,比方说我需要定时调用此异步发送邮件方法

    @Scheduled(cron = "0 1 0/1 * * ?  ")
    public void sendMailTimer() {
        ((OrderSendService) AopContext.currentProxy()).asyncSendEmail(from, to, cc,subject,text,orderList);
    }

填坑方法:
1.在类上增加 @EnableAspectJAutoProxy(exposeProxy = true) 注解

2.调用时增加 ((OrderSendService) AopContext.currentProxy())

自此springboot 实现异步发送邮件方法已完成,有不对之处,欢迎指正