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我正在使用angular2和electron编写桌面应用程序,并且有一个下载功能。Angular2 - Rxjs主题在取消订阅后运行两次
我DownloadService
是这个
import {Injectable} from '@angular/core';
import {Subject} from "rxjs";
interface IQueueItem {
url: string
}
@Injectable()
export class DownloadService {
private queue: Array<IQueueItem> = [];
private downloadSubject: Subject<any>;
constructor() {
this.downloadSubject = new Subject();
}
addToList(item: IQueueItem) {
this.queue.unshift(item);
downloadList();
return this.downloadSubject;
}
downloadList() {
// pick one item from queue and send it to electron to download and store
// do this every time a chunk of data received
this.downloadSubject.next(evt);
...
}
pauseDownload(item) {
// send an event to electron to it should stop downloading and therefore no chunk of data will receive
// also remove item from queue
...
}
}
而且我ItemComponent
是这样的:
import {Component} from '@angular/core';
import {DownloadService} from "../services/download.service";
@Component({
selector: 'app-item',
template: `
...
`
})
export class ItemComponent {
constructor(private downloadService: DownloadService) {
this.addToQueue();
}
subscription;
downloadedBytes = 0;
fileUrl = '';
pause() {
this.downloadService.pauseDownload(this.fileUrl);
this.subscription.unsubscribe();
...
}
resume() {
this.addToQueue();
}
private addToQueue() {
this.subscription = this.downloadService.addToList(this.fileUrl)
.subscribe(evt => {
console.log(evt.delta);
this.downloadedBytes += evt.delta;
});
}
}
问题是,当我停下,我从Subject
从DownloadService
通过取消一个项目,但是当我再次,每一个将简历console.log()
打印两次并将两次数据添加到downloadedBytes
。 此外,如果我暂停并再次恢复,它会添加越来越多的字节和日志!
我搜索了但我找不到任何线索解决。
我的猜测工作的例子是,它来自于事实的downloadlist()将组件列表。但是因为我们不知道这个列表是什么,当主体发出事件,它被用于什么,pauseCourse()做了什么,等等,这很难解释。提供一个完整的例子来重现问题。 –
@JBNizet对不起,我做了很多简化,显然结果并不好。我添加了更多详细信息 –
我无法复制它https://plnkr.co/edit/64mn6U1omy8JPE6LD4Nf?p=preview。检查也http://stackoverflow.com/questions/35673582/http-request-made-multiple-times-in-angular2-service – yurzui