浅谈angular9中组件动态加载的实现方法

按条件加载组件，实现组件的灵活切换，减少大量ngIf的使用，在angular中也是比较常见的操作。本篇文章就来大家一起交流一下angular组件的动态使用。有一定的参考价值，有需要的朋友可以参考一下，希望对大家有所帮助。

指令的创建

在添加组件之前，先要定义一个锚点来告诉 Angular 要把组件插入到什么地方。
在src/dynamic-banner/ad.directive.ts下

import { Directive, ViewContainerRef } from '@angular/core';

@Directive({
  selector: '[ad-host]',
})
export class AdDirective {
  constructor(public viewContainerRef: ViewContainerRef) { }
}

AdDirective 注入了 ViewContainerRef 来获取对容器视图的访问权，这个容器就是那些动态加入的组件的宿主。
在 @Directive 装饰器中，要注意选择器的名称：ad-host，它就是你将应用到元素上的指令。

相关推荐：《angular教程》

动态组件的核心代码

动态组件加载的html

src/dynamic-banner/ad-banner.component.html

<div class="ad-banner-example">
  <h3>Advertisements</h3>
  <ng-template ad-host></ng-template>
</div>

动态组件的ts

src/dynamic-banner/ad-banner.component.ts

import { Component, Input, OnInit, ViewChild, ComponentFactoryResolver, OnDestroy, SimpleChanges } from '@angular/core';

import { AdDirective } from './ad.directive';
import { AdItem }      from './ad-item';
import { AdComponent } from './ad.component';
import { componentMap } from './component/utils';
@Component({
  selector: 'app-ad-banner',
  templateUrl: './ad-banner.component.html',
  // styleUrls: ['./ad-banner.component.css']
})
export class AdBannerComponent implements OnInit {
  @Input() type: string = 'ad1' // 传入的key,确定加载那个组件
  @Input() data: any = {} // 传入组件的数据
  @ViewChild(AdDirective, {static: true}) adHost: AdDirective; // 动态组件的指令
  constructor(private componentFactoryResolver: ComponentFactoryResolver) { }

  ngOnInit() {
    this.loadComponent();
  }
  ngOnChanges(changes: SimpleChanges): void {
    if (changes['type']) this.loadComponent()
  }

  loadComponent() {
    // adItem 要加载的组件类，以及绑定到该组件上的任意数据
    const adItem = new AdItem(componentMap[this.type], this.data) 
    const componentFactory = this.componentFactoryResolver.resolveComponentFactory(adItem.component);
    const viewContainerRef = this.adHost.viewContainerRef;
    viewContainerRef.clear();
    const componentRef = viewContainerRef.createComponent(componentFactory);
    (<AdComponent>componentRef.instance).data = adItem.data;
  }
}

ad-item.ts

src/dynamic-banner/ad-item.ts

import { Type } from '@angular/core';

export class AdItem {
  constructor(public component: Type<any>, public data: any) {}
}

ad.component.ts

src/dynamic-banner/ad.component.ts

import { Type } from '@angular/core';
export interface AdComponent {
  data: any;
}

组件统一注册

src/dynamic-banner/share.module.ts

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { componets } from './component/utils';
import { AdDirective } from './ad.directive';
import { AdBannerComponent } from './ad-banner.component';

@NgModule({
  imports: [
    CommonModule
  ],
  exports:[
    [...componets],
    AdDirective,
    AdBannerComponent,
  ],
  declarations: [
    [...componets],
    AdDirective,
    AdBannerComponent,
  ],
  entryComponents: [
    [...componets]
  ]
})
export class ShareModule { }

组件的映射

src/dynamic-banner/component/utils.ts

import { HeroProfileComponent } from "./hero-profile.component";
import { HeroJobAdComponent } from './hero-job-ad.component';
const componentMap = {
    ad1: HeroProfileComponent,
    ad2: HeroJobAdComponent
}
const componets = [
    HeroProfileComponent,
    HeroJobAdComponent
]
export {componets, componentMap}

效果图

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