Golang观察者模式优化订单处理系统实例探究

type Order struct {
    ID     string
    Status string
}

type Observer interface {
    Update(order *Order, wg *sync.WaitGroup)
}

type Subject struct {
    observers []Observer
}
func (s *Subject) Register(observer Observer) {
    s.observers = append(s.observers, observer)
}
func (s *Subject) Notify(order *Order) {
    wg := sync.WaitGroup{}
    wg.Add(len(s.observers))
    errCh := make(chan error, len(s.observers))
    for _, observer := range s.observers {
        go func(obs Observer) {
            defer wg.Done()
            err := obs.Update(order, &wg)
            if err != nil {
                errCh <- err
            }
        }(observer)
    }
    wg.Wait()
    close(errCh)
    // 处理异常
    for err := range errCh {
        fmt.Println("Error occurred:", err)
    }
}

type InventoryObserver struct{}
func (io *InventoryObserver) Update(order *Order, wg *sync.WaitGroup) {
    defer wg.Done()
    // 更新库存状态
    fmt.Printf("Inventory Observer: Order %s status changed to %s\n", order.ID, order.Status)
}

type NotificationObserver struct{}
func (no *NotificationObserver) Update(order *Order, wg *sync.WaitGroup) {
    defer wg.Done()
    // 发送通知
    fmt.Printf("Notification Observer: Order %s status changed to %s\n", order.ID, order.Status)
}

func main() {
    order := &Order{
        ID:     "123",
        Status: "Created",
    }
    subject := &Subject{}
    subject.Register(&InventoryObserver{})
    subject.Register(&NotificationObserver{})
    // 模拟订单状态变化
    order.Status = "Paid"
    subject.Notify(order)
    order.Status = "Shipped"
    subject.Notify(order)
}

type Order struct {
    ID     string
    Status string
}
type OrderProcessor struct {
    inventoryObserver    *InventoryObserver
    notificationObserver *NotificationObserver
}
func NewOrderProcessor() *OrderProcessor {
    return &OrderProcessor{
        inventoryObserver:    &InventoryObserver{},
        notificationObserver: &NotificationObserver{},
    }
}
func (op *OrderProcessor) Process(order *Order) {
    // 更新库存
    op.inventoryObserver.Update(order)
    // 发送通知
    op.notificationObserver.Update(order)
}
func main() {
    order := &Order{
        ID:     "123",
        Status: "Created",
    }
    op := NewOrderProcessor()
    // 模拟订单状态变化
    order.Status = "Paid"
    op.Process(order)
    order.Status = "Shipped"
    op.Process(order)
}