如何使用Observer替换订户？

Question

GitHub上的This问题几乎总结了它。我使用timer()以1秒的重复计划执行某项任务。我将它与Subscriber配对以订阅间隔。当某个模型用完数据时，我取消订阅并等待新到货。当他们再次填充数据时，我尝试再次订阅但它不起作用。事实证明，当Subscriber未被取消时，我不能再使用它了。所以我必须用Observer替换它。这是一个新手，我不知道该怎么做。试着看一些例子，他们只是把我弄糊涂了。

如何使用Observer替换以下代码？

private timer = timer(1000, 1000);

// A timer subscription that keeps sending new images to the observer
timerSubscription = new Subscriber(() => {

    // Check if there is an element in the list
    if (this.head != null) {

      // If the current node at head is a folder, unsubscribe the listener
      if (this.head.data['id'].startsWith('folder')) {
        this.timerSubscription.unsubscribe();
      }

      // Pop a node from the list and pass on to observer
      this.observer.next(this.this$PiFrame.pop());

    } else {

      // If no nodes are left, unsubscribe from the timer
      this.timerSubscription.unsubscribe();

      console.log('No items left on the queue. Deactivating timer subscription.');
    }
  }, e => {}, () => {});

我订阅如下：

    ...
    // Setup a timer to pop every 1000 ms
    this.timer.subscribe(this.this$PiFrame.timerSubscription);
    ...
    // If no nodes are left, unsubscribe from the timer
    this.timerSubscription.unsubscribe();
    ...

Answer 1

不要像你那样创建订阅，而是让Observable返回订阅。

将逻辑保留在函数中，如下所示：

  doWhatever() {
    console.log("tick")

    // Check if there is an element in the list
    if (this.head != null) {

      // If the current node at head is a folder, unsubscribe the listener
      if (this.head.data['id'].startsWith('folder')) {
        this.timerSubscription.unsubscribe();
      }

      // Pop a node from the list and pass on to observer
      this.observer.next(this.this$PiFrame.pop());

    } else {

      // If no nodes are left, unsubscribe from the timer
      this.timerSubscription.unsubscribe();

      console.log('No items left on the queue. Deactivating timer subscription.');
    }
  }

然后，当你想订阅时：

this.timerSubscription = this.timer.subscribe(() => this.doWhatever());

这可以重复使用，因为每个subscribe生成一个新的Subscription