Golang观察者模式与事件机制详解

type Event string

type Observer interface {
    OnNotify(Event)
}

type Subject interface {
    Register(Observer)
    Deregister(Observer)
    Notify(Event)
}

type EventBus struct {
    observers []Observer
    mutex     sync.RWMutex
}

func NewEventBus() *EventBus {
    return &EventBus{
        observers: make([]Observer, 0),
    }
}

func (bus *EventBus) Register(obs Observer) {
    bus.mutex.Lock()
    defer bus.mutex.Unlock()
    bus.observers = append(bus.observers, obs)
}

func (bus *EventBus) Deregister(obs Observer) {
    bus.mutex.Lock()
    defer bus.mutex.Unlock()
    for i, observer := range bus.observers {
        if observer == obs {
            bus.observers = append(bus.observers[:i], bus.observers[i+1:]...)
            break
        }
    }
}

func (bus *EventBus) Notify(event Event) {
    bus.mutex.RLock()
    defer bus.mutex.RUnlock()
    for _, obs := range bus.observers {
        obs.OnNotify(event)
    }
}

type Logger struct{}

func (l *Logger) OnNotify(event Event) {
    fmt.Printf("日志记录: %s\n", event)
}

type Notifier struct{}

func (n *Notifier) OnNotify(event Event) {
    fmt.Printf("发送通知: %s\n", event)
}

func main() {
    bus := NewEventBus()

    logger := &Logger{}
    notifier := &Notifier{}

    bus.Register(logger)
    bus.Register(notifier)

    bus.Notify("user.login")
    bus.Deregister(notifier)
    bus.Notify("user.logout")
}

日志记录: user.login
发送通知: user.login
日志记录: user.logout