在Angular-Cli中，@Input和@Output始终是未定义的

// 子组件
import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'app-child',
  template: `
    <p>{{ childMessage }}</p>
    <button (click)="sendMessage()">Send Message</button>
  `
})
export class ChildComponent {
  @Input() childMessage: string;
  @Output() messageEvent = new EventEmitter<string>();

  sendMessage() {
    this.messageEvent.emit('Hello from child!');
  }
}

// 父组件
import { Component } from '@angular/core';

@Component({
  selector: 'app-parent',
  template: `
    <app-child [childMessage]="parentMessage" (messageEvent)="receiveMessage($event)"></app-child>
  `
})
export class ParentComponent {
  parentMessage = 'Hello from parent!';

  receiveMessage($event) {
    console.log($event);
  }
}