如何在Angular中获取订阅元素

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class DataService {
  getData(): Observable<any> {
    return new Observable(observer => {
      // 模拟异步操作
      setTimeout(() => {
        observer.next('Data fetched');
        observer.complete();
      }, 2000);
    });
  }
}

import { Component, OnInit, OnDestroy } from '@angular/core';
import { DataService } from './data.service';
import { Subscription } from 'rxjs';

@Component({
  selector: 'app-my-component',
  template: `<div>{{ data }}</div>`
})
export class MyComponent implements OnInit, OnDestroy {
  data: string;
  private subscription: Subscription;

  constructor(private dataService: DataService) {}

  ngOnInit() {
    this.subscription = this.dataService.getData().subscribe(
      data => {
        this.data = data;
      },
      error => {
        console.error('Error fetching data', error);
      },
      () => {
        console.log('Data fetch completed');
      }
    );
  }

  ngOnDestroy() {
    if (this.subscription) {
      this.subscription.unsubscribe();
    }
  }
}

ngOnDestroy() {
  if (this.subscription) {
    this.subscription.unsubscribe();
  }
}

import { Subject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';

@Component({
  selector: 'app-my-component',
  template: `<div>{{ data }}</div>`
})
export class MyComponent implements OnInit, OnDestroy {
  data: string;
  private destroy$ = new Subject<void>();

  constructor(private dataService: DataService) {}

  ngOnInit() {
    this.dataService.getData()
      .pipe(takeUntil(this.destroy$))
      .subscribe(
        data => {
          this.data = data;
        },
        error => {
          console.error('Error fetching data', error);
        }
      );
  }

  ngOnDestroy() {
    this.destroy$.next();
    this.destroy$.complete();
  }
}