java - 发送电子邮件时出现 Spring 错误

Question

这个问题已经有答案了:

Why is my Spring @Autowired field null? (21 个回答)

已关闭 5 年前。

我尝试使用 spring 框架发送电子邮件。我是初学者，所以请随时解释或建议我。我有以下 bean 声明

 @Configuration
public class EmailConfig {

     @Bean
        public JavaMailSender getMailSender(){
            JavaMailSenderImpl mailSender = new JavaMailSenderImpl();

            //Using gmail
            mailSender.setHost("smtp.gmail.com");
            mailSender.setPort(587);
            mailSender.setUsername("xxxxxx@gmail.com");
            mailSender.setPassword("xxxxxx");

            Properties javaMailProperties = new Properties();
            javaMailProperties.put("mail.smtp.starttls.enable", "true");
            javaMailProperties.put("mail.smtp.auth", "true");
            javaMailProperties.put("mail.transport.protocol", "smtp");
            javaMailProperties.put("mail.debug", "true");//Prints out everything on screen

            mailSender.setJavaMailProperties(javaMailProperties);
            return mailSender;
        }

}

这是我发送电子邮件的类(class)

public class SendEmail {

private JavaMailSender mailSender;

public void setMailSender(JavaMailSender mailSender) {
    this.mailSender = mailSender;
}

public void send(String to, String subject, String text){

    SimpleMailMessage message = new SimpleMailMessage();
    message.setTo(to);
    message.setSubject(subject);
    message.setText(text);
    mailSender.send(message);
  }

}

我在上面使用了

 try{
     SendEmail mm = new SendEmail();
     mm.send("abc@gmail.com", "do not reply", "this is the template mesage");
 }catch(Exception ex){
     ex.printStackTrace();
 }

上面的代码给出了以下控制台错误

java.lang.NullPointerException
    at com.sparktronix.mvc.mail.SendEmail.send(SendEmail.java:20)
    at com.sparktronix.mvc.controllers.RegistrationController.userRegistration(RegistrationController.java:142)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

at com.sparktronix.mvc.mail.SendEmail.send(SendEmail.java:20)

这个错误是针对

  public void send(String to, String subject, String text){

     SimpleMailMessage message = new SimpleMailMessage();
     message.setTo(to);
     message.setSubject(subject);
     message.setText(text);
     mailSender.send(message); } //this line is creating the error

如果有人帮助我就好了。欢迎任何建议。提前致谢

Answer 1

Spring 不知道你的服务。一种方法是:

@Service
public class SendEmailService {

   @Autowired
   @Setter //using lombok
   private JavaMailSenderImpl mailSender;

   public void send(String to, String subject, String text){

       SimpleMailMessage message = new SimpleMailMessage();
       message.setTo(to);
       message.setSubject(subject);
       message.setText(text);
       mailSender.send(message);
   }
}

请注意，上面的类用 @Service 进行注释，并且我们 Autowiring (依赖项注入(inject))mailSender。您也可以使用构造函数注入(inject)。

当你想调用该服务时，你可以这样做:

@Autowired
private SendEmailService sendEmailService;

try {
    sendEmailService.send("abc@gmail.com", "do not reply", "this is the template mesage");
} 
catch (Exception ex) {
   ex.printStackTrace(); //but use a logger instead
}