4.生命周期 发送http请求

4-1 生命周期 ngOnInit

export class AppComponent {
  title = 'my-app';
  ngOnInit(){
    console.log("init")
  }
}

4-2 http请求

//app.module.ts
//导入
import {HttpClientModule} from '@angular/common/http'
//注册 
imports: [
    HttpClientModule
 ]

//app.component.ts
//导入
import {HttpClient} from '@angular/common/http'
export class AppComponent {
  music:any=[];
  title = 'my-app';
  //作为函数的参数注册
  constructor(public http:HttpClient){}
    ngOnInit(){
    var url:string="http://localhost:8000/top250";
    this.http.get(url).subscribe((res:any)=>{
      console.log(res)
      this.music=res.playlists;
    })
    console.log("init")
  }
  }