SpringBoot 動態配置郵箱發件人

SpringBoot 動態配置郵箱發件人

現在的消息模塊少不了郵件發送、短信發送和手機推送的功能。郵件發送的功能歷史最為悠久，也算的上爛大街的功能。一般在配置文件中設置好郵箱地址、賬號、密碼和發件服務器地址后便不會再去改動。可是有的客戶卻希望人為指定發件人信息。這個需求並不過分，需要解決兩個大問題：如何在容器啟動成功后重新修改發送郵件的Bean。如何在服務器重啟后，發件人依然是更改后的配置信息。這里記錄實現的步驟。

需求分析

一）、在未配置郵箱賬號時，系統擁有默認的郵箱發件人

二）、重新設置郵箱發件人后，需立即生效

三）、重啟服務器后，郵箱發件人依然是更改后的郵箱賬號，而非默認發件人

基礎的郵箱發送

郵箱發送的功能放在現在變得非常的簡單好用，一導二配三發送。😊

第一步：導入郵箱依賴包

compile('org.springframework.boot:spring-boot-starter-mail')

第二步：配置發件人郵箱信息

spring:
    mail:
      host: smtp.mxhichina.com
      username: itdragon@xx
      password: itdragon
      default-encoding: utf-8

第三步：發送郵件

@Autowired
lateinit var javaMailSender: JavaMailSender

fun pushMsgEmail(target: String, subject: String, content: String) {
    if (target.isEmpty() || !Pattern.matches(REG_EMAIL_FORMAT, target)) return
    val mailMsg = SimpleMailMessage()
    mailMsg.setFrom(mailUserName!!)
    mailMsg.setTo(target)
    mailMsg.setSubject(subject)
    mailMsg.setText(content)
    javaMailSender.send(mailMsg)
}

可配置的郵件發送

這里的可配置值的是配置郵箱的發件人。首先我們要解決第一個問題，JavaMailSender 的Bean對象是在容器啟動成功后就已經注入到容器中。如何在容器啟動后重新注入新的JavaMailSender 的Bean對象呢？網上找了一些案例，他們都是通過銷毀Bean然后再重新創建Bean的方式實現。我有點好奇地是，為什么不直接將新的對象直接賦值從而替換原有的Bean對象？Spring默認是單例模式，從Java內存的角度看，這樣做似乎沒毛病！如果有不對的地方望不吝賜教😋

@Autowired
lateinit var javaMailSender: JavaMailSender

fun configEmail(postMailConfig: PostMailConfig): JavaMailSender {
    val javaMailSender = JavaMailSenderImpl()
    javaMailSender.host = postMailConfig.mailHost
    javaMailSender.username = postMailConfig.mailUsername
    javaMailSender.password = postMailConfig.mailPassword
    val javaMailProperties = Properties()
    javaMailProperties["mail.smtp.auth"] = true
    javaMailProperties["mail.smtp.starttls.enable"] = true
    javaMailProperties["mail.smtp.timeout"] = 5000
    javaMailProperties["mail.smtp.socketFactory.class"] = "javax.net.ssl.SSLSocketFactory"
    javaMailProperties["mail.smtp.socketFactory.port"] = "465"
    javaMailProperties["mail.smtp.port"] = "465"
    javaMailSender.javaMailProperties = javaMailProperties
    this.javaMailSender = javaMailSender
    return javaMailSender
}

再來解決第二個問題，服務器重啟后，默認情況下依然會重新加載application.yml中的配置信息。這會出現郵箱發件人和實際配置的發件人不匹配的情況。其實這個問題也很好解決，加一個事件監聽器，在容器初始化成功后執行，根據之前保存的郵箱信息，重新配置郵箱。當然，我們需要一張表記錄當前發件人信息。

// 創建事件監聽器
class ApplicationStartup : ApplicationListener<ContextRefreshedEvent> {
    
    override fun onApplicationEvent(contextRefreshedEvent: ContextRefreshedEvent) {
        val systemBaseConfigMapper = contextRefreshedEvent.applicationContext.getBean(SystemBaseConfigMapper::class.java)
        val postMailConfig = systemBaseConfigMapper.selectByMail()
        val mailService = contextRefreshedEvent.applicationContext.getBean(MailService::class.java)
        mailService.configEmail(postMailConfig)
    }
    
}

// 注冊事件監聽器
fun main(args: Array<String>) {
    
    val springApplication = SpringApplication(StartApplication::class.java)
    springApplication.addListeners(ApplicationStartup())
    springApplication.run(*args)
    
}

最后發送郵件的代碼如下

@Service
class MailServiceImpl : MailService {

    @Value("\${spring.mail.username}")
    var mailUserName: String? = null

    @Autowired
    lateinit var javaMailSender: JavaMailSender
    @Autowired
    lateinit var systemBaseConfigMapper: SystemBaseConfigMapper

    override fun pushMsgEmail(target: String, subject: String, content: String) {
        if (target.isEmpty() || !Pattern.matches(REG_EMAIL_FORMAT, target)) return
        val mailMsg = SimpleMailMessage()
        mailMsg.setFrom(mailUserName!!)
        mailMsg.setTo(target)
        mailMsg.setSubject(subject)
        mailMsg.setText(content)
        try {
            systemBaseConfigMapper.selectByMailName()?.let {
                mailMsg.setFrom(it.value!!)
            }
            javaMailSender.send(mailMsg)
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

    override fun configEmail(postMailConfig: PostMailConfig): JavaMailSender {
        val javaMailSender = JavaMailSenderImpl()
        javaMailSender.host = postMailConfig.mailHost
        javaMailSender.username = postMailConfig.mailUsername
        javaMailSender.password = postMailConfig.mailPassword
        val javaMailProperties = Properties()
        javaMailProperties["mail.smtp.auth"] = true
        javaMailProperties["mail.smtp.starttls.enable"] = true
        javaMailProperties["mail.smtp.timeout"] = 5000
        javaMailProperties["mail.smtp.socketFactory.class"] = "javax.net.ssl.SSLSocketFactory"
        javaMailProperties["mail.smtp.socketFactory.port"] = "465"
        javaMailProperties["mail.smtp.port"] = "465"
        javaMailSender.javaMailProperties = javaMailProperties
        this.javaMailSender = javaMailSender
        return javaMailSender
    }

}

文章到這里就結束了，感謝閱讀！ths！