Gmail Api在Spring启动：javax.mail.MessagingException：无法将套接字转换为TLS

Question

我正在使用spring boot的后端，我试图使用smtp向gmail帐户发送电子邮件，但我发现了一些错误。

这是我在本教程之后的代码：

应用属性：

spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.username=[e-mail]
spring.mail.password=xxxpwd
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true

类MailObject。java：

    package interv.Web.Notifications;

import org.hibernate.validator.constraints.Email;

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

public class MailObject {

    @Email
    @NotNull
    @Size(min = 1, message = "Please, set an email address to send the message to it")
    private String to;
    private String subject;
    private String text;

    public String getTo() {
        return to;
    }

    public void setTo(String to) {
        this.to = to;
    }

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }
}

邮件ontroller.java：

    @Controller
public class MailController {

    @Autowired
    public EmailServiceImpl emailService;

    @Autowired
    public SimpleMailMessage template;

    @RequestMapping(value = "/send", method = RequestMethod.POST)
    public String createMail(@RequestBody MailObject mailObject) {


        emailService.sendSimpleMessage(mailObject.getTo(),
                mailObject.getSubject(), mailObject.getText());

        return "that was succesfull";

    }
}

电子邮件服务。Java语言

public interface EmailService {

    void sendSimpleMessage(String to,
                           String subject,
                           String text);
    void sendSimpleMessageUsingTemplate(String to,
                                        String subject,
                                        SimpleMailMessage template,
                                        String templateArgs);

}

EmailServiceImpl.java

@Component
public class EmailServiceImpl implements EmailService{

    @Autowired
    public JavaMailSender emailSender;

    @Override
    public void sendSimpleMessage(String to, String subject, String text) {
        SimpleMailMessage message = new SimpleMailMessage();
        message.setTo(to);
        message.setSubject(subject);
        message.setText(text);

        emailSender.send(message);
    }

    @Override
    public void sendSimpleMessageUsingTemplate(String to, String subject, SimpleMailMessage template, String templateArgs) {
        String text = String.format(template.getText(), templateArgs);
        sendSimpleMessage(to, subject, text);
    }
}

运行时，控制台中没有错误，但当我尝试发送电子邮件时，会出现以下错误：

servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.mail.MailSendException: Mail server connection failed; nested exception is javax.mail.MessagingException: Could not convert socket to TLS;
  nested exception is:
    javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target. Failed messages: javax.mail.MessagingException: Could not convert socket to TLS;
  nested exception is:
    javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target; message exceptions (1) are:
Failed message 1: javax.mail.MessagingException: Could not convert socket to TLS;
  nested exception is:
    javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target] with root cause

sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141) ~[na:1.8.0_161]
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126) ~[na:1.8.0_161]
    at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280) ~[na:1.8.0_161]

我不明白为什么我会犯这个错误：有什么想法吗？

Answer 1

错误明确表示“UnknownHost”。检查你的应用程序是否可以访问internet并能够解析名称。

Answer 2

我认为原因是，出于安全原因，Gmail默认情况下会阻止对不太安全的应用程序的访问检查这个类似的问题，它的答案可能会帮助你错误地使用Gmail发送电子邮件