Angular 2订阅了另一个异步功能的服务

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

@Injectable({
  providedIn: 'root'
})
export class DataService {
  constructor(private http: HttpClient) {}

  getData(): Observable<any> {
    return this.http.get('https://api.example.com/data');
  }
}

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

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent implements OnInit {
  private subscription: Subscription;

  constructor(private dataService: DataService) {}

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

  ngOnDestroy() {
    // 取消订阅以防止内存泄漏
    if (this.subscription) {
      this.subscription.unsubscribe();
    }
  }
}

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

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent implements OnInit, OnDestroy {
  private unsubscribe$ = new Subject<void>();

  constructor(private dataService: DataService) {}

  ngOnInit() {
    this.dataService.getData()
      .pipe(takeUntil(this.unsubscribe$))
      .subscribe(
        data => console.log('Data received:', data),
        error => console.error('Error occurred:', error)
      );
  }

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