Spring中使用ApplicationEvent机制，实际项目开发使用

Spring中使用事件非常简单，只需要以下的几个步骤：

• 1.定义事件，继承ApplicationEvent
• 2.定义监听，要么实现ApplicationListener接口，要么在方法上添加@EventListener注解
• 3.定义发布事件借口，调用ApplicationContext.publishEvent()或者ApplicationEventPublisher.publishEvent();
• 4.业务调用发布事件

业务场景： 注册账号完成之后，需要将账号信息同步到权限平台。
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@Data
public class baseAsgardEvent extends ApplicationEvent {
    private T data;

    public baseAsgardEvent(Object source) {
        super(source);
    }

    public baseAsgardEvent(Object source,T data){
        super(source);
        this.data = data;
    }
}

//自定义事件需要继承ApplicationEvent
public class UserRegisterEvent extends ApplicationEvent {
    private String username;
    public UserRegisterEvent(Object source, String username) {
        super(source);
        this.username = username;
    }
    public String getUsername() {
        return username;
    }
}

//可以实现ApplicationListener接口监听事件
@Component
@Order(2)//可以使用order指定顺序，越小优先级越高
public class MailUserRegisterListener implements ApplicationListener {
    @Override
    public void onApplicationEvent(UserRegisterEvent event) {
        System.out.println(Thread.currentThread().getName()+"-给用户"+event.getUsername()+"发送邮件！");
    }
}
//也可以使用@EventListener监听事件
@Component
@Order(1)
public class CouponUserRegisterListener {
    @EventListener
    public void sendCoupon(UserRegisterEvent event) {
        System.out.println(Thread.currentThread().getName()+"-给用户"+event.getUsername()+"发送优惠券!");
    }
}

@Component
@Slf4j
public class AccountEventListener {

    @Autowired
    UniformAccessClient uniformAccessClient;
    @Autowired
    AccountMapper accountMapper;


    @EventListener
    public void merchantBusinessRecordEventListener(baseAsgardEvent event) {

        Account account = event.getData();
        try {
            if (account == null) {
                return;
            }
            AccountPO accountPO = accountMapper.selectByPrimaryKey(account.getId());
            //调用权限平台服务，同步信息
            uniformAccessClient.syncAccountToUniformAccessClient(accountPO);
        } catch (Exception e) {
            log.error("商户档案变更，同步发送消息失败", e);
        }
    }


}

@Component
public class SpringContextHolder implements ApplicationContextAware {

    private static ApplicationContext applicationContext = null;

    
    public static ApplicationContext getApplicationContext() {
        assertContextInjected();
        return applicationContext;
    }

    
    @SuppressWarnings("unchecked")
    public static  T getBean(String name) {
        assertContextInjected();
        return (T) applicationContext.getBean(name);
    }

    
    public static  T getBean(Class requiredType) {
        assertContextInjected();
        return applicationContext.getBean(requiredType);
    }

    
    public static void clearHolder() {
        applicationContext = null;
    }

    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        SpringContextHolder.applicationContext = applicationContext;
    }

    
    private static void assertContextInjected() {
        Validate.validState(applicationContext != null,
                "applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder.");
    }


    //包装方法
    public static void publish(Object event) {
        applicationContext.publishEvent(event);
    }



}

@Service
public class TestMethod {


    
    public void store(Account account) {
    //处理账号业务。。。。。。。。。。。
    //处理其他业务完成。。。。。。。。。。。

        //商户账号 同步
        baseAsgardEvent event = new baseAsgardEvent("ACCOUNT", account);
        SpringContextHolder.publish(event);

    }
    }