关于rxjs subject订阅分发实现Angular的全局数据管理与同步更新

Import {subject}from’rxjs’
Subject 数据的订阅与分发，结合报刊的发布与订阅进行功能的模拟，subject即是observeable对象也是observer对象，subject对于后期没有数据更新时所添加的订阅者是不怎么友好的，因为不跟新数据时订阅者就不在收到返回的数值
    const interval$ = interval(1000).pipe(take(10));
    const subject = new Subject();

    const observerA = {
      next: value => console.log('Observer A get value: ' + value),
      error: error => console.log('Observer A error: ' + error),
      complete: () => console.log('Observer A complete!'),
    };

    const observerB = {
      next: value => console.log('Observer B get value: ' + value),
      error: error => console.log('Observer B error: ' + error),
      complete: () => console.log('Observer B complete!'),
    };

    subject.subscribe(observerA); // 添加观察者A
    interval$.subscribe(subject); // 订阅interval$对象
    setTimeout(() => {
      subject.subscribe(observerB); // 添加观察者B
    }, 1000);

Import{BehaviorSubject}from’rxjs’;
behaviorSubject 是subject的变种，最大的区别就是 behaviorSubject是用于保存最新的数值，而不是单纯的发送事件，会将最后一次发送的值作为当前值保存在内部属性中。
    const subject = new BehaviorSubject(0);  //BehaviorSubject小括号0代表的是状态
    const observerA = {
      next: value => console.log('Observer A get value: ' + value),
      error: error => console.log('Observer A error: ' + error),
      complete: () => console.log('Observer A complete!'),
    };

    const observerB = {
      next: value => console.log('Observer B get value: ' + value),
      error: error => console.log('Observer B error: ' + error),
      complete: () => console.log('Observer B complete!'),
    };

    subject.subscribe(observerA); // 添加观察者A
    // interval$.subscribe(subject); // 订阅interval$对象
    subject.next(1);
    subject.next(2);
    subject.next(3);
    setTimeout(() => {
      subject.subscribe(observerB); // 添加观察者B
    }, 1000);

Import {ReplaySubject}from’rxjs’;
ReplaySubject 用于重复发送最近几次的值给订阅者
    const subject = new ReplaySubject(2); //ReplaySubject后的2为最后两次发送的数值
    const observerA = {
      next: value => console.log('Observer A get value: ' + value),
      error: error => console.log('Observer A error: ' + error),
      complete: () => console.log('Observer A complete!'),
    };

    const observerB = {
      next: value => console.log('Observer B get value: ' + value),
      error: error => console.log('Observer B error: ' + error),
      complete: () => console.log('Observer B complete!'),
    };

    subject.subscribe(observerA); // 添加观察者A
    // interval$.subscribe(subject); // 订阅interval$对象
    subject.next(1);
    subject.next(2);
    subject.next(3);
    setTimeout(() => {
      subject.subscribe(observerB); // 添加观察者B
    }, 1000);

Import{AsyncSubject}from’rxjs’;
AsyncSubject他会在subject完成后才返回一个值
    const subject = new AsyncSubject();
    const observerA = {
      next: value => console.log('Observer A get value: ' + value),
      error: error => console.log('Observer A error: ' + error),
      complete: () => console.log('Observer A complete!'),
    };

    const observerB = {
      next: value => console.log('Observer B get value: ' + value),
      error: error => console.log('Observer B error: ' + error),
      complete: () => console.log('Observer B complete!'),
    };

    subject.subscribe(observerA); // 添加观察者A
    // interval$.subscribe(subject); // 订阅interval$对象
    subject.next(1);
    subject.next(2);
    subject.next(3);
    subject.complete();
    setTimeout(() => {
      subject.subscribe(observerB); // 添加观察者B
    }, 1000);

import { NgModule, ModuleWithProviders } from '@angular/core';
import { SomeSharedService } from './window.service';
export { SomeSharedService };

@NgModule()
export class ServicesModule {
  static forRoot(): ModuleWithProviders {
    return {
      ngModule: ServicesModule,
      providers: [SomeSharedService],
    };
  }
}

import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs';
@Injectable()
export class SomeSharedService {
  public globalVar: BehaviorSubject<any> = new BehaviorSubject({
    dataCount1: 0,
    dataCount2: 0,
    dataCount3: 0,
    dataSum: 0,

  });
  settingKey(key, sumKey) {
    const globalVar = this.globalVar.getValue();
    globalVar[key] -= 1;
    globalVar[sumKey] -= 1;
    this.globalVar.next(globalVar);
  }
}