Golang观察者模式实现教程

type Observer interface {
    Update(message string)
}

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

type EventCenter struct {
    observers []Observer
}

func (ec *EventCenter) Register(o Observer) {
    ec.observers = append(ec.observers, o)
}

func (ec *EventCenter) Deregister(o Observer) {
    for i, observer := range ec.observers {
        if observer == o {
            ec.observers = append(ec.observers[:i], ec.observers[i+1:]...)
            break
        }
    }
}

func (ec *EventCenter) Notify(message string) {
    for _, observer := range ec.observers {
        observer.Update(message)
    }
}

type EmailLogger struct{}

func (el *EmailLogger) Update(message string) {
    fmt.Println("Email Logger:", message)
}

type FileLogger struct{}

func (fl *FileLogger) Update(message string) {
    fmt.Println("File Logger:", message)
}

func main() {
    eventCenter := &EventCenter{}

    emailLogger := &EmailLogger{}
    fileLogger := &FileLogger{}

    eventCenter.Register(emailLogger)
    eventCenter.Register(fileLogger)

    eventCenter.Notify("User logged in") 
    // 输出：
    // Email Logger: User logged in
    // File Logger: User logged in

    eventCenter.Deregister(emailLogger)
    eventCenter.Notify("Data updated") 
    // 只有 File Logger 会收到
}