家长班：

export let SF = new OpaqueToken('sf');
 
export class A {
  testMsg: string = 'hello';
}
 
@Component({
  template: `<child></child>`,providers: [
    provide(SF,{useValue: A}),provide('justString',{useValue: 'hi'}) 
  ]
})
export class App {}

儿童班：

import {Component,Injector,Inject,OpaqueToken} from 'angular2/core'
import {SF,A} from './app'
console.log("******",SF); // undefined
@Component({
  selector: 'child',template: `
    $$CHILD Rendered$${{a}}
  `
})
export class Child {
  //constructor(@Inject(SF) private a: A) {} // doesn't work
  constructor(@Inject('justString') private a: string) {}
}

我得到的例外情况：

angular2.min.js:17EXCEPTION: Cannot resolve all parameters for ‘Child'(@Inject(undefined)). Make sure that all the parameters are decorated with Inject or have valid type annotations and that ‘Child’ is decorated with Injectable.