angular2中Http请求原理与用法详解

import { HttpModule, JsonpModule } from '@angular/http'; @NgModule({ imports: [ HttpModule, JsonpModule ], })

angular-in-memory-web-api

npm install angular-in-memory-web-api --save-dev

This in-memory web api service processes an HTTP request and returns an Observable of HTTP Response object in the manner of a RESTy web api.

:base/:collectionName/:id? GET api/heroes // all heroes GET api/heroes/42 // the character with id=42 GET api/heroes?name=^j // 'j' is a regex; returns heroes whose name starting with 'j' or 'J' GET api/heroes.json/42 // ignores the ".json"

之前测试时用的app/mock/user_data_memory_mock.ts数据

import {User} from '../model/User'; import { InMemoryDbService } from 'angular-in-memory-web-api'; export class UserDataMemoryMock implements InMemoryDbService{ createDb() { const users: User[] = [ new User('chenjianhua_a', 21, '2290910211@qq.com', '123456'), new User('chenjianhua_b', 22, '2290910211@qq.com', '123456'), new User('chenjianhua_c', 23, '2290910211@qq.com', '123456'), new User('chenjianhua_d', 24, '2290910211@qq.com', '123456'), new User('chenjianhua_e', 25, '2290910211@qq.com', '123456'), new User('chenjianhua_f', 26, '2290910211@qq.com', '123456'), ]; return {users}; } }

编辑app.module.ts

import { InMemoryWebApiModule } from 'angular-in-memory-web-api'; import { UserDataMemoryMock } from './mock/user_data_memory_mock'; @NgModule({ imports: [ InMemoryWebApiModule.forRoot(UserDataMemoryMock), ] })

导入InMemoryWebApiModule并将其加入到模块的imports数组。 InMemoryWebApiModule将Http客户端模拟的后端服务
forRoot()配置方法需要UserMemoryMockService类实例，用来向内存数据库填充数据

编辑app/service/user.restful.service.ts

import {Injectable} from '@angular/core'; import { Headers, Http } from '@angular/http'; import 'rxjs/add/operator/toPromise'; import { User } from '../model/User'; import { Logger } from './logger.service'; @Injectable() export class UserService { private USERURL = 'api/users'; private headers = new Headers({'Content-Type': 'application/json'}); constructor(private Log: Logger, private http: Http) { } getUserByName(name: string): Promise<User> { const url = `${this.USERURL}/?name=${name}`; return this.http.get(url) .toPromise() .then(response => response.json().data as User) .catch(this.handleError); } getUsers(): Promise<User[]> { console.log('Get User!'); return this.http.get(this.USERURL) .toPromise() .then(response => response.json().data as User[]) .catch(this.handleError); } create(name: string): Promise<User> { return this.http .post(this.USERURL, JSON.stringify({name: name}), {headers: this.headers}) .toPromise() .then(res => res.json().data as User) .catch(this.handleError); } private handleError(error: any): Promise<any>{ console.log('An error occurred :', error); return Promise.reject(error.message); } }

编辑app/components/app-loginform/app.loginform.ts

import { Component, OnInit } from '@angular/core'; import { Logger } from '../../service/logger.service'; import { UserService } from '../../service/user.restful.service'; import { User } from '../../model/User'; import { Subject } from 'rxjs/Subject'; @Component({ selector: 'app-loginform', templateUrl: './app.loginform.html', styleUrls: ['./app.loginform.css'], providers: [ Logger, UserService ] }) export class AppLoginFormComponent implements OnInit { users: User[]; submitted = false; model = new User('1', 'fangfang', 22, '2290910211@qq.com', '123456'); constructor( private Log: Logger, private userService: UserService ){} ngOnInit(): void{ this.userService .getUsers() .then( users => this.users = users); } onSubmit(): void { this.userService.getUserByName(this.model.name) .then( user => { console.log('user.name', user[0].name); console.log('user.password', user[0].password); if(user[0].name === this.model.name && user[0].password === this.model.password){ this.Log.log('login success!'); this.submitted = true; }else{ this.Log.log('login failed!'); this.submitted = false; } }) .catch(errorMsg => console.log(errorMsg)); } }

HTTP Promise

Angular 的http.get返回一个 RxJS 的Observable对象。 Observable是一个管理异步数据流的强力方式。

现在，我们先利用toPromise方法把Observable直接转换成Promise对象

更多关于AngularJS相关内容感兴趣的读者可查看本站专题：《AngularJS指令操作技巧总结》、《AngularJS入门与进阶教程》及《AngularJS MVC架构总结》