问题描述
我正在一个项目中，我的意图是执行一项玉米工作并将邮件发送给我的朋友，祝他们生日快乐，我能够从MysqL DB获得电子邮件并将其与当前日期进行比较，但是在发送电子邮件时，我收到NullPointerException。
我确定应用程序属性没有问题，我也将它们与其他项目一起使用，并且它们可以正常运行
//Imports
package dev.teja.happybirthday;
import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.*;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import javax.persistence.*;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.validation.constraints.Email;
import freemarker.template.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;
import org.springframework.ui.freemarker.FreeMarkerTemplateUtils;
import org.springframework.web.bind.annotation.*;
//Main
@SpringBootApplication
public class HappybirthdayApplication {
public static void main(String[] args) {
SpringApplication.run(HappybirthdayApplication.class,args);
}
@Autowired
MyFriendsRepository myFriendsRepository ;
@Scheduled(cron = "*/30 * * * * *")
void WishMyFriends() {
List<MyFriends> myFriendsList = myFriendsRepository.findAll();
myFriendsList.forEach(friend -> {
Date date = new Date();
SimpleDateFormat formatter = new SimpleDateFormat("dd/MM");
String CurrentDate= formatter.format(date);
String Givendate = formatter.format(friend.dob);
if (Givendate.equals(CurrentDate)){
Job job = new Job();
Map<String,Object> model = new HashMap<>();
model.put("Name",friend.name);
job.sendWish(friend.email,model);
}
});
}
}
@Configuration
@ConditionalOnProperty(name = "scheduling.enabled",matchIfMissing = true)
@EnableScheduling
class Tasks {
}
//Model
@Data
@Setter
@Getter
@NoArgsConstructor
@AllArgsConstructor
@ToString
@Entity
class MyFriends {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
Long id;
String name;
@Email
@Column(unique = true)
String email;
@JsonFormat(pattern = "dd/MM/yyyy",shape = JsonFormat.Shape.STRING)
Date dob;
Long phoneNumber;
}
//Repository
interface MyFriendsRepository extends JpaRepository<MyFriends,Long> {
}
@RestController
@RequestMapping("/")
class FriendsController {
@Autowired
MyFriendsRepository myFriendsRepository;
@PostMapping("/friends")
ResponseEntity<MyFriends> createFriend(@RequestBody MyFriends myFriend) {
myFriendsRepository.save(myFriend);
return new ResponseEntity<MyFriends>(myFriend,HttpStatus.CREATED);
}
@GetMapping("/friends")
List<MyFriends> getFriends() {
return myFriendsRepository.findAll();
}
}
//Interface
interface wisher{
void sendWish(String email,Map<String,Object> model);
}
//Implementation
@Service
class Job implements wisher{
@Autowired
private JavaMailSender sender;
@Autowired
private freemarker.template.Configuration config;
@Override
public void sendWish(String email,Object> model) {
System.out.println("wishes sent to "+ email);
MimeMessage message = sender.createMimeMessage();
try {
MimeMessageHelper helper = new MimeMessageHelper(message,MimeMessageHelper.MULTIPART_MODE_MIXED_RELATED,StandardCharsets.UTF_8.name());
Template template = config.getTemplate("new-template.ftl");
String html = FreeMarkerTemplateUtils.processtemplateIntoString(template,model);
helper.setTo(email);
helper.setFrom("kondasaitej@gmail.com");
helper.setSubject("Happy Birthday");
helper.setText(html,true);
sender.send(message);
} catch (MessagingException | IOException | TemplateException e) {
e.printstacktrace();
}
}
}
FreeMaker文件
/**
* FREEMAKER new-template.ftl
* <html xmlns="http://www.w3.org/1999/xhtml">
* <head>
* <Meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
* <title>Comment Alert Mail</title>
* </head>
* <body>
* <p>happy birthday ${Name}</p>
* </body>
*/
这是我正在得到的错误
Hibernate: select myfriends0_.id as id1_0_,myfriends0_.dob as dob2_0_,myfriends0_.email as email3_0_,myfriends0_.name as name4_0_,myfriends0_.phone_number as phone_nu5_0_ from my_friends myfriends0_
wishes sent to kondasaitej@protonmail.com
2020-09-26 21:01:52.012 ERROR 84242 --- [ scheduling-1] o.s.s.s.TaskUtils$LoggingErrorHandler : Unexpected error occurred in scheduled task
java.lang.NullPointerException: null
at dev.teja.happybirthday.Job.sendWish(HappybirthdayApplication.java:115) ~[classes/:na]
at dev.teja.happybirthday.HappybirthdayApplication.lambda$WishMyFriends$0(HappybirthdayApplication.java:53) ~[classes/:na]
at java.util.ArrayList.forEach(ArrayList.java:1257) ~[na:1.8.0_251]
at dev.teja.happybirthday.HappybirthdayApplication.WishMyFriends(HappybirthdayApplication.java:44) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_251]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_251]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_251]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_251]
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84) ~[spring-context-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) ~[spring-context-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93) [spring-context-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_251]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_251]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_251]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [na:1.8.0_251]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_251]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_251]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_251]
解决方法
尝试添加进入@Autowired私有JavaMailSender发件人；
,我认为您尚未实现JavaMailSender bean。如下定义一个bean。然后您的@Autowire批注将起作用。
@Bean
public JavaMailSender getJavaMailSender()
{
JavaMailSenderImpl mailSender = new JavaMailSenderImpl();
mailSender.setHost("smtp.gmail.com");
mailSender.setPort(25);
mailSender.setUsername("admin@gmail.com");
mailSender.setPassword("password");
Properties props = mailSender.getJavaMailProperties();
props.put("mail.transport.protocol","smtp");
props.put("mail.smtp.auth","true");
props.put("mail.smtp.starttls.enable","true");
props.put("mail.debug","true");
return mailSender;
}