import { Injectable } from '@angular/core';import {Observable} from 'rxjs';@Injectable({providedIn: 'root'
})
export class RequestService {constructor() { }//同步
  getData(){return 'this is service data';}getCallbackData(cb){setTimeout(() => {var username='张三';// return username;
      cb(username);}, 1000);}getPromiseData(){return new Promise((resolve)=>{      setTimeout(() => {var username='张三--Promise';resolve(username);        }, 3000); })}getRxjsData(){return new Observable<any>((observer)=>{setTimeout(() => {var username='张三--Rxjs';observer.next(username);     // observer.error('数据')        }, 3000); })}//多次执行
getPromiseIntervalData(){return new Promise((resolve)=>{      setInterval(() => {var username='张三--Promise  Interval';resolve(username);        }, 1000); })}getRxjsIntervalData(){let count=0;return new Observable<any>((observer)=>{setInterval(() => {count++;var username='张三--Rxjs-Interval'+count;observer.next(username);     // observer.error('数据')        }, 1000); })}getRxjsIntervalNum(){let count=0;return new Observable<any>((observer)=>{setInterval(() => {count++;observer.next(count);     // observer.error('数据')        }, 1000); })}}

import { Component, OnInit } from '@angular/core';
import { RequestService } from '../../services/request.service';
import {map,filter} from 'rxjs/operators';
@Component({selector: 'app-home',templateUrl: './home.component.html',styleUrls: ['./home.component.scss']
})
export class HomeComponent implements OnInit {constructor( public request:RequestService) { }runParent(msg:string){//接收子组件传递过来的数据 runParent(msg:string){    alert(msg);}public title='新闻标题'ngOnInit() {//1、同步方法
let data=this.request.getData();console.log(data);//2、callback获取异步数据this.request.getCallbackData((data)=>{console.log(data);});//3、promise获取异步数据var promiseData=this.request.getPromiseData();promiseData.then((data)=>{console.log(data);})//4、rxjs获取异步方法里面的数据var rxjsData=this.request.getRxjsData();rxjsData.subscribe((data)=>{console.log(data);})//5、过一秒以后撤回刚才的操作var streem=this.request.getRxjsData();var d=streem.subscribe((data)=>{console.log(data);})setTimeout(()=>{d.unsubscribe();  /*取消订阅*/},1000)//6、promise 执行多次（没有这个能力）var intervalData=this.request.getPromiseIntervalData();intervalData.then((data)=>{console.log(data);})//7、rxjs执行多次var streemInterval=this.request.getRxjsIntervalData();streemInterval.subscribe((data)=>{console.log(data);})//8、用工具方法对返回的数据进行处理var streemNum=this.request.getRxjsIntervalNum();streemNum.pipe(filter((value)=>{if(value%2==0){return true;}}))      .subscribe((data)=>{console.log(data);})var streemNum=this.request.getRxjsIntervalNum();streemNum.pipe(map((value)=>{return value*value;}))      .subscribe((data)=>{console.log(data);})var streemNum=this.request.getRxjsIntervalNum();streemNum.pipe(filter((value)=>{if(value%2==0){return true;}}),map((value)=>{return value*value;}))      .subscribe((data)=>{console.log(data);})}}