如果 spring.mail.host 不在 application.properties 中，则 JavaMailSenderImpl Autowiring 错误

Question

我在使用 JavaMailSenderImpl 在我的 spring boot 应用程序中发送电子邮件时遇到了一些“问题”。

我正在尝试动态设置所有属性(我希望将来从数据库中读取它们)但是，出于我不知道的原因， Autowiring JavaMailSenderImpl 仅在我的“spring.mail.host”存在时才有效应用程序.属性。

我设置的值无关紧要(它可以为空，这无关紧要，因为我稍后设置了正确的值)，但该属性必须存在，否则 Autowiring 将失败。

这是我的 Controller :

import java.util.Properties;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mail.MailException;
import org.springframework.mail.SimpleMailMessage;
import org.springframework.mail.javamail.JavaMailSenderImpl;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;


@Controller
public class MailController {

    @Autowired
    private JavaMailSenderImpl ms;


    @RequestMapping("/mail")
    public String send(Model model){

        SimpleMailMessage message;
        String fromEmail="sdfsdf98435sadf@gmail.com";
        String toEmail ="xxxxxxx";

        Properties mailProperties = new Properties();
        mailProperties.put("mail.smtp.starttls.enable", true);
        mailProperties.put("mail.smtp.ssl.trust", "smtp.gmail.com");

        ms.setHost("smtp.gmail.com");
        ms.setPort(587);
        ms.setUsername("xxxx");
        ms.setPassword("yyyyy");
        ms.setJavaMailProperties(mailProperties);

        message = new SimpleMailMessage();
        message.setSubject("Test email");
        message.setFrom(fromEmail);
        message.setTo(toEmail);
        message.setText("Something something");

        try{
            ms.send(message);
        }
        catch(MailException ex){
            System.err.println(ex.getMessage());
        }
        return "OK";
    }

}

将与此应用程序一起正常工作(发送电子邮件)。属性:

#springboot-starter-mail properties
spring.mail.host=

但是如果我删除那行，将会抛出这个异常:

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.mail.javamail.JavaMailSenderImpl] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1373) ~[spring-beans-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1119) ~[spring-beans-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1014) ~[spring-beans-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:545) ~[spring-beans-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    ... 19 common frames omitted

我可以把空的属性(property)留在那里，但感觉不对。

任何想法可能是什么原因？

Answer 1

Autowiring 接口(interface) JavaMailSender 而不是实现。

@Autowired
private JavaMailSender mailSender;