Asynchronous, email and scheduled tasks

Asynchronous task

1. establish service package , Create a class under it AsyncService

   Forgery is processing data , Cause thread delay , Analog synchronization waiting .

   package com.hxl.service;
   
   import org.springframework.stereotype.Service;
   
   @Service
   public class AsyncService {
         
   
       public void hello(){
         
           try {
         
               Thread.sleep(3000);
           } catch (InterruptedException e) {
         
               e.printStackTrace();
           }
           System.out.println(" Data processing ....");
       }
   }
   

2. establish controller package , Create a class under it AsyncController

   package com.hxl.controller;
   
   import com.hxl.service.AsyncService;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RestController;
   
   @RestController
   public class AsyncController {
         
       @Autowired
       AsyncService asyncService;
   
       @RequestMapping("/hello")
       public String hello(){
         
           asyncService.hello();
           return " No problem ";
       }
   }
   

3. Access test http://localhost:8080/hello, At this time, you can find the web page waiting 3 It will appear in seconds No problem The words... . This is the situation of synchronous waiting .

4. In order to make the user experience better , Let the user get the message first , Then the background uses multithreading to process the results . We need to add a comment , such ,Springboot Will open a thread pool , To call .

   // tell Spring This is an asynchronous method 
   @Async
   public void hello(){
         
       try {
         
           Thread.sleep(3000);
       } catch (InterruptedException e) {
         
           e.printStackTrace();
       }
       System.out.println(" Data processing ....");
   }
   

   You also need to add an annotation to the main launcher , Let the asynchronous annotation turn on

   @EnableAsync // Turn on the asynchronous annotation function 
   @SpringBootApplication
   public class SpringbootAsyncApplication {
         
   
       public static void main(String[] args) {
         
           SpringApplication.run(SpringbootAsyncApplication.class, args);
       }
   
   }
   

5. At this time, the test found , The web page will open instantly , But the background data will continue , Until the end of data processing .

Email tasks

1. Introduce dependencies

   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-mail</artifactId>
   </dependency>
   

   You can see the relevant email sending dependencies

   

2. see JavaMailSenderImpl After finding it , Look at the configuration file, that is properties Under the , We can see the relevant configuration

3. take QQ The service in the mailbox is turned on , We use IMAP/SMTP service

   

4. The configuration file

   [email protected]
   spring.mail.password= Their own QQ Authorization code 
   spring.mail.host=smtp.qq.com
   spring.mail.properties.mail.smtp.ssl.enable=true
   

5. test

   package com.hxl;
   
   import org.junit.jupiter.api.Test;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.boot.test.context.SpringBootTest;
   import org.springframework.mail.SimpleMailMessage;
   import org.springframework.mail.javamail.JavaMailSenderImpl;
   import org.springframework.mail.javamail.MimeMessageHelper;
   
   import javax.mail.MessagingException;
   import javax.mail.internet.MimeMessage;
   import java.io.File;
   
   @SpringBootTest
   class SpringbootAsyncApplicationTests {
         
   
       @Autowired
       JavaMailSenderImpl mailSender;
   
       @Test
       void contextLoads() {
         
           // A simple email 
           SimpleMailMessage message = new SimpleMailMessage();
           message.setSubject(" Tomorrow will be a holiday ");
           message.setText(" direct 10 Day long vacation ");
   
           message.setTo("[email protected]");
           message.setFrom("[email protected]");
           mailSender.send(message);
       }
   
       @Test
       public void contextLoads2() throws MessagingException {
         
           // A complicated email 
           MimeMessage mimeMessage = mailSender.createMimeMessage();
           MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true);
   
           helper.setSubject(" Tomorrow will be a holiday ");
           helper.setText("<b style='color:red'> What do you think </b>",true);
   
           // Sending attachments 
           helper.addAttachment("1.jpg",new File(" Path to file "));
           helper.addAttachment("2.jpg",new File(" such as ：D:\\2.jpg"));
   
           helper.setTo("[email protected]");
           helper.setFrom("[email protected]");
   
           mailSender.send(mimeMessage);
       }
   }
   

   Then you can see that our email was sent successfully .

Timing task

TaskExecutor Interface 

TaskScheduler Interface 

Two notes ：

• @EnableScheduling // Note on timing function , In the main boot class
• @Scheduled // When to execute

test

1. establish Service package , Create a class ScheduledService

   package com.hxl.service;
   
   import org.springframework.scheduling.annotation.Scheduled;
   import org.springframework.stereotype.Service;
   
   @Service
   public class ScheduledService {
         
   
       // Execute this method at a specific time 
       //cron expression 
       // second   branch   when   Japan   month   What day of the week 
       // The following sentence is from Monday to Sunday , Of 0 second 
       @Scheduled(cron = "0 * * * * 0-7")
       public void hello(){
         
           System.out.println("hello, You've been executed ");
       }
   }
   

2. Add... To the main program @EnableScheduling Turn on timed task function

   package com.hxl;
   
   import org.springframework.boot.SpringApplication;
   import org.springframework.boot.autoconfigure.SpringBootApplication;
   import org.springframework.scheduling.annotation.EnableAsync;
   import org.springframework.scheduling.annotation.EnableScheduling;
   
   @EnableAsync // Turn on the asynchronous annotation function 
   @EnableScheduling  // Note on timing function 
   @SpringBootApplication
   public class SpringbootAsyncApplication {
         
   
       public static void main(String[] args) {
         
           SpringApplication.run(SpringbootAsyncApplication.class, args);
       }
   
   }
   

3. And then it's all right

cron expression

cron：https://baike.baidu.com/item/cron/10952601?fr=aladdin

cron Generation ：https://www.bejson.com/othertools/cron/