Angular7创建项目、组件、服务以及服务的使用

npm install -g @angular/cli

ng new pybbs-front-angular

import { UserService } from './user/user.service';

@NgModule({
 providers: [
  UserService
 ]
})

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

@Injectable({
 providedIn: 'root'
})
export class TopicService {

 constructor(private http: HttpClient) { }

 fetchGithubApi() {
  return new Observable((observe) => {
   const httpOptions = { headers: new HttpHeaders({ 'Content-Type': 'application/json' }) };
   this.http.get('https://api.github.com', httpOptions)
    .subscribe((data: any) => {
     observe.next(data.detail);
     // 如果有错误，通过 error() 方法将错误返回
     // observe.error(data.description);
    });
  });
 }
}

import { Component, OnInit } from '@angular/core';
import { ActivatedRoute } from '@angular/router';
import { UserService } from './user.service';

@Component({
 selector: 'app-user',
 templateUrl: './user.component.html',
 styleUrls: ['./user.component.scss']
})
export class UserComponent implements OnInit {

 constructor(
  private userService: UserService
 ) { }

 ngOnInit() {
  this.userService.fetchGithubApi()
   .subscribe(data => console.log(data), error => console.log(error));
 }

}