ng g s services/user

在app.module.ts中引入服务

import {UserService} from "./services/user.service";

providers: [UserService],

使用servies需要引入服务 在users.service.ts

import { Http } from '@angular/http' ;

在app.module.ts文件中需要引入http的模块

import { HttpModule } from "@angular/http";

在imports文件中引用模块

imports: [

HttpModule

],

 

在ng6中会报错可以用下面的代替

user.service.ts中

import { HttpClient } from "@angular/common/http";

app.module.ts中

import { HttpClientModule } from "@angular/common/http";

imports: [

HttpClientModule,

]

user.service.ts中

Constructor()中需要声明 HttpClient

constructor(private http: HttpClient) {}

请求数据：

1. 引入map  

import { map } from "rxjs/operators";

2、创建请求方法

getUsers() {

return this.http.get("http://localhost:3000/users").pipe(map(res => res));

 }

1. 在需要引入服务的ts文件去取值 例如:user.component.ts文件中

import { UserService } from "../../services/user.service";

constructor(public userService: UserService) {}

ngOnInit() {

    this.userService.getUsers().subscribe(user => {

      console.log(user);

      this.users = user;

    });

  }