詳解SpringBoot實現ApplicationEvent事件的監聽與釋出

2023-03-09 06:00:26

新建SpringBoot專案

專案結構

.
├── pom.xml
└── src
└── main
├── java
│ └── com
│ └── example
│ └── demo
│ ├── Application.java
│ ├── config
│ │ └── TaskPoolConfig.java
│ ├── controller
│ │ └── IndexController.java
│ ├── entity
│ │ └── EmailDto.java
│ ├── event
│ │ └── SendEmailEvent.java
│ ├── listener
│ │ └── SendEmailListener.java
│ └── service
│ ├── SendEmailService.java
│ └── impl
│ └── SendEmailServiceImpl.java
└── resources
├── application.yml
├── static
└── templates

實現程式碼

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.7</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

Application.java

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

TaskPoolConfig.java

package com.example.demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.Executor;


/**
 * 執行緒池引數設定
 **/
@EnableAsync
@Configuration
public class TaskPoolConfig {
    /**
     * 自定義執行緒池
     **/
    @Bean
    public Executor taskExecutor() {
        //返回可用處理器的Java虛擬機器器的數量 12
        int i = Runtime.getRuntime().availableProcessors();
        System.out.println("系統最大執行緒數  ： " + i);

        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        //核心執行緒池大小
        executor.setCorePoolSize(16);
        //最大執行緒數
        executor.setMaxPoolSize(20);
        //設定佇列容量，預設值為Integer.MAX_VALUE
        executor.setQueueCapacity(99999);
        //活躍時間
        executor.setKeepAliveSeconds(60);
        //執行緒名字字首
        executor.setThreadNamePrefix("asyncServiceExecutor -");
        //設定此執行程式應該在關閉時阻止的最大秒數，以便在容器的其餘部分繼續關閉之前等待剩餘的任務完成他們的執行
        executor.setAwaitTerminationSeconds(60);
        //等待所有的任務結束後再關閉執行緒池
        executor.setWaitForTasksToCompleteOnShutdown(true);

        return executor;
    }
}

EmailDto.java

package com.example.demo.entity;

import lombok.Data;

@Data
public class EmailDto {
    private String email;
    private String subject;
    private String content;
}

SendEmailEvent.java

package com.example.demo.event;

import com.example.demo.entity.EmailDto;
import org.springframework.context.ApplicationEvent;

/**
 * 自定義事件
 */
public class SendEmailEvent extends ApplicationEvent {
    private EmailDto emailDto;

    public SendEmailEvent(EmailDto emailDto) {
        super(emailDto);
        this.emailDto = emailDto;
    }

    public EmailDto getEmailDto() {
        return this.emailDto;
    }
}

SendEmailListener.java

package com.example.demo.listener;

import com.example.demo.entity.EmailDto;
import com.example.demo.event.SendEmailEvent;
import com.example.demo.service.SendEmailService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationListener;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Component;

/**
 * 事件監聽器
 */
@Component
public class SendEmailListener implements ApplicationListener<SendEmailEvent> {
    @Autowired
    private SendEmailService sendEmailService;

    @Async
    @Override
    public void onApplicationEvent(SendEmailEvent event) {
        EmailDto emailDto = event.getEmailDto();
        this.sendEmailService.sendEmail(emailDto);
    }
}

SendEmailService.java

package com.example.demo.service;

import com.example.demo.entity.EmailDto;

public interface SendEmailService {
    void sendEmail(EmailDto emailDto);
}

SendEmailServiceImpl.java

package com.example.demo.service.impl;

import com.example.demo.entity.EmailDto;
import com.example.demo.service.SendEmailService;
import org.springframework.stereotype.Service;

@Service
public class SendEmailServiceImpl implements SendEmailService {
    @Override
    public void sendEmail(EmailDto emailDto) {
        try {
            // 模擬耗時3秒
            Thread.sleep(3 * 1000);
        } catch (Exception e) {
            System.out.println("Email傳送異常");
        }

        System.out.println("Email傳送成功 " + emailDto);
    }
}

IndexController.java

package com.example.demo.controller;

import com.example.demo.entity.EmailDto;
import com.example.demo.event.SendEmailEvent;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;


@RestController
public class IndexController {
    @Autowired
    private ApplicationEventPublisher publisher;

    @GetMapping("/sendEmail")
    public String sendEmail() {
        EmailDto emailDto = new EmailDto();
        emailDto.setEmail("tom@qq.com");
        emailDto.setSubject("郵件標題");
        emailDto.setContent("郵件內容");

        // 釋出事件
        publisher.publishEvent(new SendEmailEvent(emailDto));
        return "success";
    }
}

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