1. 子组件引入 Output 和 EventEmitter;子组件中实例化 EventEmitter;子组件通过 EventEmitter 对象 outer 实例广播数据

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

@Component({
  selector: 'app-son',
  templateUrl: './son.component.html',
  styleUrls: ['./son.component.css']
})
export class SonComponent implements OnInit {

  @Output() private outer=new EventEmitter<string>();
  constructor() { }

  sendParent(){
    this.outer.emit('msg from child')
  }

  ngOnInit() {
    this.sendParent();
  }
}

2 父组件调用子组件的时候，定义接收事件 , outer 就是子组件的 EventEmitter 对象 outer

<app-son (outer)="runParent($event)"></app-son>>

3 父组件接收到数据会调用自己的 runParent 方法，这个时候就能拿到子组件的数据

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

@Component({
  selector: 'app-father',
  templateUrl: './father.component.html',
  styleUrls: ['./father.component.css']
})
export class FatherComponent implements OnInit {

  public msg2;
  constructor() { }

  ngOnInit() {
    this.msg2 = "test";
  }

  runParent(msg:string){
    this.msg2 = msg;
  }

}