6、http请求

//app.module.ts中去注册
import {HttpClientModule} from '@angular/common/http'  //注册http请求
@NgModule({
  ...
  imports: [
    BrowserModule,
    HttpClientModule
  ]
  ...
})

//app.component.ts配置
import {HttpClient} from '@angular/common/http'  //配置http请求
export class AppComponent {
  constructor(public http:HttpClient){}
  ngOnInit(){
     var url:string = "http://localhost:8000/top250";
     this.http.get(url).subscribe(res=>{
       console.log(res)
     })
  }
}