angular2使用sse并创建可观察对象，然后求解get值，但组件没有结果

import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs/Observable';

@Component({
  selector: 'app-example',
  template: `
    <div>{{ value }}</div>
  `
})
export class ExampleComponent implements OnInit {
  value: string;

  ngOnInit() {
    const eventSource = new EventSource('/api/events'); // 替换为你的SSE端点

    Observable.fromEvent(eventSource, 'message')
      .subscribe((event: MessageEvent) => {
        this.value = event.data;
      });
  }
}