angular2中Http请求原理与用法详解

本文实例讲述了angular2中Http请求原理与用法。分享给大家供大家参考，具体如下：提供HTTP

本文实例讲述了angular2中Http请求原理与用法。分享给大家供大家参考，具体如下：

提供HTTP服务

HttpModule并不是Angular的核心模块。 它是Angular用来进行Web访问的一种可选方式，并位于一个名叫@angular/http的独立附属模块中.

编辑app.module.ts

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