通过app.module定义模块的父子关系（记得导入对应的模块）：

import { AppComponent } from './app.component';
import { ParentComponent } from './main/parent/parent.component';
import { SonComponent } from './main/son/son.component';
import { SonaddComponent } from './main/sonadd/sonadd.component';
import { WelcomeComponent } from './welcome/welcome.component';

// If your are not using lazy loading, you need to import your HomeComponent in app.module and mention it under declarations. Also, don't forget to remove from imports
 

const routes: Routes = [
    {
        path: '',
        redirectTo: '/home',
        pathMatch: 'full'
    },
    {
        path: 'home',
        component: WelcomeComponent
    },
    {
      path: 'parent',
      component: ParentComponent,
      children:[
        {
          path: 'son',
          component: SonComponent
        },
        {
          path: '',
          component: SonComponent
        },
        {
          path: 'sonadd',
          component: SonaddComponent
        },
      ]
    },
     
];
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父子组件间的通信：