SpringBoot利用观察者模式实现联动更新机制

import org.springframework.context.ApplicationEvent;

public class StudentAgeUpdateEvent extends ApplicationEvent {

    private static final long serialVersionUID = 1L;

    private final Long studentId;
    private final int newAge;

    public StudentAgeUpdateEvent(Object source, Long studentId, int newAge) {
        super(source);
        this.studentId = studentId;
        this.newAge = newAge;
    }

    public Long getStudentId() {
        return studentId;
    }

    public int getNewAge() {
        return newAge;
    }
}

import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

@Component
public class StudentRecordUpdater implements ApplicationListener<StudentAgeUpdateEvent> {

    private final StudentRecordRepository studentRecordRepository;

    public StudentRecordUpdater(StudentRecordRepository studentRecordRepository) {
        this.studentRecordRepository = studentRecordRepository;
    }

    @Override
    public void onApplicationEvent(StudentAgeUpdateEvent event) {
        Long studentId = event.getStudentId();
        int newAge = event.getNewAge();
        // 更新学生档案表
        studentRecordRepository.updateAge(studentId, newAge);
    }
}

import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

@Component
public class StudentScoreUpdater implements ApplicationListener<StudentAgeUpdateEvent> {

    private final StudentScoreRepository studentScoreRepository;

    public StudentScoreUpdater(StudentScoreRepository studentScoreRepository) {
        this.studentScoreRepository = studentScoreRepository;
    }

    @Override
    public void onApplicationEvent(StudentAgeUpdateEvent event) {
        Long studentId = event.getStudentId();
        int newAge = event.getNewAge();
        // 更新学生成绩表
        studentScoreRepository.updateAge(studentId, newAge);
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Service;

@Service
public class StudentService {

    private final ApplicationEventPublisher eventPublisher;

    @Autowired
    public StudentService(ApplicationEventPublisher eventPublisher) {
        this.eventPublisher = eventPublisher;
    }

    public void updateStudentAge(Long studentId, int newAge) {
        // 更新学生表中的年龄
        // ...
        
        // 发布事件
        eventPublisher.publishEvent(new StudentAgeUpdateEvent(this, studentId, newAge));
    }
}

import org.springframework.transaction.annotation.Transactional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Service;

@Service
@Transactional
public class StudentService {

    // ... 其他代码保持不变
}