java springboot 事件驱动开发最小示例

项目结构

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1. pom.xml（只保留最小依赖）

<?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>3.2.0</version>
        <relativePath/>
    </parent>
    <groupId>com.example</groupId>
    <artifactId>event-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>event-demo</name>

    <properties>
        <java.version>17</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
</project>

2. 自定义事件 UserRegisterEvent.java

package com.example.eventdemo.event;

import org.springframework.context.ApplicationEvent;

// 自定义事件：用户注册事件
public class UserRegisterEvent extends ApplicationEvent {
    // 事件携带的数据
    private final String username;

    // 继承 ApplicationEvent 需要完成的
    public UserRegisterEvent(Object source, String username) {
        super(source);
        this.username = username;
    }
	// 额外提供
    public String getUsername() {
        return username;
    }
}

3. 事件发布 Service UserService.java

未来会在控制器里面使用

package com.example.eventdemo.service;

import com.example.eventdemo.event.UserRegisterEvent;
import lombok.RequiredArgsConstructor;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Service;

@Service
@RequiredArgsConstructor  // 自动新建 ApplicationEventPublisher
public class UserService {

    // Spring 内置事件发布器
    private final ApplicationEventPublisher eventPublisher;

    public void register(String username) {
        System.out.println("[业务] 用户注册主逻辑：" + username);

        // 发布事件
        eventPublisher.publishEvent(new UserRegisterEvent(this, username));
    }
}

4. 事件监听器 UserEventListener.java

package com.example.eventdemo.listener;

import com.example.eventdemo.event.UserRegisterEvent;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;

@Component
public class UserEventListener {

    // 监听 UserRegisterEvent
    @EventListener
    public void onUserRegister(UserRegisterEvent event) {
        String username = event.getUsername();
        System.out.println("[监听器] 收到注册事件，发送欢迎邮件给：" + username);
    }

    // 可以多个监听器监听同一个事件，互不影响
    @EventListener
    public void anotherListener(UserRegisterEvent event) {
        System.out.println("[监听器2] 新增用户统计：" + event.getUsername());
    }
}

5. 测试 Controller TestController.java

package com.example.eventdemo.controller;

import com.example.eventdemo.service.UserService;
import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequiredArgsConstructor
public class TestController {

    private final UserService userService;

    @GetMapping("/register")
    public String register(@RequestParam String username) {
        userService.register(username);
        return "ok";
    }
}

6. 启动类 EventDemoApplication.java

package com.example.eventdemo;

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

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

测试

启动后访问：

http://localhost:8080/register?username=zhangsan

控制台输出顺序（同步）：

[业务] 用户注册主逻辑：zhangsan
[监听器] 收到注册事件，发送欢迎邮件给：zhangsan
[监听器2] 新增用户统计：zhangsan