Angular 5 StaticInjectorError:[Http]

Question

您好，我收到这样一个错误，这是什么原因？

StaticInjectorErrorHttp: StaticInjectorErrorHttp: NullInjectorError:没有提供程序！在NullInjector.get (core.js:923)在resolveToken (core.js:1211)在tryResolveToken (core.js:1153)在StaticInjector.get (core.js:1024)在resolveToken (core.js:1211)在tryResolveToken (core.js:1153)在StaticInjector.get (core.js:1024)在resolveNgModuleDep (core.js:10585)在NgModuleRef.get (core.js:11806)在resolveDep ()输入代码

import { Injectable } from '@angular/core' import {Todo} from './Todo'

import {Http, Response,Headers,RequestOptions} from '@angular/Http' import {Observable} from 'rxjs/Observable' import 'rxjs/add/operator/do' import 'rxjs/add/operator/catch' import 'rxjs/add/operator/map'

@Injectable() export class TodoService{

constructor(private http: Http){}

todoUrl = "https://jsonplaceholder.typicode.com/todos";

getTodos():Observable{ return this.http.get("https://jsonplaceholder.typicode.com/todos") .map((res:Response)=>res.json()) .do(data=>console.log("TODOS LIST")) } }