如何在 Angular 2 中正确地在组件之间共享服务数据
我想创建一个服务来从 .json 文件中获取一次数据并将其共享给多个订阅者.但是现在我的解决方案从 .json 文件中获取数据的请求数等于我的服务的订阅者数.
I want to create a service to get data from .json file once and share it to multiple subscribers. But now with my solution number of requests to get data from .json file equals to a number of a subscibers for my service.
getconfig.service.ts
getconfig.service.ts
import {Injectable} from 'angular2/core';
import {Http, Response} from "angular2/http";
@Injectable()
export class ConfigService {
config: any;
http: Http;
constructor(http: Http) {
this.http = http;
console.log('Inside service');
this.config = this.http.get('/config.json');
}
}robotui.component.ts
robotui.component.ts
...
import {ConnectionService} from '../services/connection.service';
@Component({
...
providers: [HTTP_PROVIDERS, ConfigService, ConnectionService]
...
})
constructor(private _configService: ConfigService) {
this._configService.config.subscribe((observer) => {
console.log('Subscribe in RobotUI component', JSON.parse(observer._body));
});
}actual.photo.component.ts
actual.photo.component.ts
import {Component} from 'angular2/core';
import {ConfigService} from '../services/getconfig.service';
@Component({
...
providers: [ConfigService]
})
export class ActualPhotoComponent {
constructor(private _configService: ConfigService) {
this._configService.config.subscribe((observer) => {
console.log('Subscribe in ActualPhoto component', JSON.parse(observer._body));
});
}
}当我在控制台中运行它时，我看到:
When i run it in my console i see:
因此，每个订阅者都有获取请求.当我只获得一次 config.json 文件时，我想要一个解决方案，将此信息保存在服务中并与多个订阅者共享.
So, there is get request for each subscibers. I want a solution when i get config.json file only once, save this info in a service and share it with multiple subscibers.
推荐答案
那是因为
@Component({
...
providers: [ConfigService] //<--- this creates service instance per component
})
<小时>
要在控制器/组件之间共享数据并仅创建单个实例，您必须将服务注入 bootstrap 函数.
import {ConfigService } from './path to service';
bootstrap('AppCompoent',[configService]) //<----Inject here it will create a single instance only
在订阅组件中，
robotui.component.ts
...
import {ConfigService} from '../services/getconfig.service'; //<----- Note this line here....
import {ConnectionService} from '../services/connection.service';
@Component({
...
... // No providers needed anymore
...
})
constructor(private _configService: ConfigService) {
this._configService.config.subscribe((observer) => {
console.log('Subscribe in RobotUI component', JSON.parse(observer._body));
});
}
actual.photo.component.ts
import {Component} from 'angular2/core';
import {ConfigService} from '../services/getconfig.service';
@Component({
...
... // No providers needed anymore...
})
export class ActualPhotoComponent {
constructor(private _configService: ConfigService) {
this._configService.config.subscribe((observer) => {
console.log('Subscribe in ActualPhoto component', JSON.parse(observer._body));
});
}
}
这是你应该做的.
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