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动手写一个angular版本的Message组件的方法

2019-11-19 14:43:21
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学习一个框架或库的最好方法是看官方文档,并着手去写例子。最近在利用空闲的时间学习angular,那今天就尝试写一个message组件,并通过message服务动态加载message组件。
我所参与的项目基本是用jquery完成的。之前,在项目中自己动手写过一个简单的message插件,样子如下图。

那现在就使用angular(版本5.0.0)来实现message组件。

message组件

message组件要根据传入的类型、消息和duration来显示。创建三个文件:message.component.ts,message.component.html,message.component.css,代码如下。

//message.component.tsimport {Component,Input,OnInit,ChangeDetectionStrategy} from '@angular/core';import {  trigger,  state,  style,  transition,  animate } from '@angular/animations';const mapping={  success:'glyphicon-ok-sign',  warning:'glyphicon-exclamation-sign',  error:'glyphicon-exclamation-sign',  info:'glyphicon-ok-circle'}@Component({  selector:'upc-ng-message',  templateUrl:'./message.component.html',  styleUrls:['./message.component.css'],  changeDetection:ChangeDetectionStrategy.OnPush})export class MessageComponent implements OnInit{  ngOnInit(): void {    this.typeClass=['upc-message-' + this.msgType];    this.typeIconClass=[mapping[this.msgType]];  }  @Input() msgType:'success' | 'info' | 'warning' | 'error'='info'  @Input() payload:string = ''  private typeClass  private typeIconClass}
<!--*message.component.html--><div class="upc-message">    <div class="upc-message-content" [ngClass]="typeClass">      <i class="glyphicon" [ngClass]="typeIconClass"></i>      {{payload}}    </div></div>
.upc-message {  position: fixed;  z-index: 1999;  width: 100%;  top: 36px;  left: 0;  pointer-events: none;  padding: 8px;  text-align: center; } .upc-message i {   margin-right: 8px;   font-size: 14px;   top: 1px;   position: relative; } .upc-message-success i {   color: green; } .upc-message-warning i {   color: yellow; } .upc-message-error i {   color: red; } .upc-message-content {   padding: 8px 16px;   -ms-border-radius: 4px;   border-radius: 4px;   -webkit-box-shadow: 0 2px 8px #000000;   -ms-box-shadow: 0 2px 8px #000000;   box-shadow: 0 2px 8px #000000;   box-shadow: 0 2px 8px rgba(0,0,0,.2);   background: #fff;   display: inline-block;   pointer-events: all; }

ComponentLoader

通过官方文档动态组件一节,可以了解动态创建组件需要通过ComponentFactoryResolver来完成。使用ComponentFactoryResolver创建ComponentFactory,再通过ComponentFactory的create方法创建组件。看官方文档中API的说明,ComponentFactory的create方法至少需要一个injector参数,而injector的创建在文档中也有提到,其中参数providers为需要注入的类。再梳理下整个过程:

  1. 提供providers
  2. 创建Injector实例
  3. 创建ComponetFactory
  4. 使用ComponetFactory创建ComponentRef
//ComponentFactory的create方法create(injector: Injector, projectableNodes?: any[][], rootSelectorOrNode?: string|any, ngModule?: NgModuleRef<any>): ComponentRef<C>//使用Injector的create创建injector实例static create(providers: StaticProvider[], parent?: Injector): Injector

为了代码的复用,这里创建通用的loader类来完成组件的动态创建。其中,attch方法用于初始化ComponetFactory(参数为组件类型);to方法用于标识组件的父容器;provider方法用于初始化可注入的类;create方法用于创建组件并手动变更检测;remove方法用于移除组件。

import {  ComponentFactoryResolver,  ComponentFactory,  ComponentRef,  Type,  Injector,  Provider,  ElementRef} from '@angular/core';export class ComponentLoader<T>{  constructor(private _cfr: ComponentFactoryResolver,    private _injector: Injector) {  }  private _componentFactory: ComponentFactory<T>  attch(componentType: Type<T>): ComponentLoader<T> {    this._componentFactory = this._cfr.resolveComponentFactory<T>(componentType);    return this;  }  private _parent: Element  to(parent: string | ElementRef): ComponentLoader<T> {    if (parent instanceof ElementRef) {      this._parent = parent.nativeElement;    } else {      this._parent = document.querySelector(parent);    }    return this;  }  private _providers: Provider[] = [];  provider(provider: Provider) {    this._providers.push(provider);  }  create(opts: {}): ComponentRef<T> {    const injector = Injector.create(this._providers as any[], this._injector);    const componentRef = this._componentFactory.create(injector);    Object.assign(componentRef.instance, opts);    if (this._parent) {      this._parent.appendChild(componentRef.location.nativeElement);    }    componentRef.changeDetectorRef.markForCheck();    componentRef.changeDetectorRef.detectChanges();    return componentRef;  }  remove(ref:ComponentRef<T>){    if(this._parent){      this._parent.removeChild(ref.location.nativeElement)    }    ref=null;  }}

同时,为了便于loader的创建,再创建LoaderFactory类,代码如下:

import {  ComponentFactoryResolver,  Injector,  Injectable,  ElementRef} from '@angular/core';import { ComponentLoader } from './component-loader.class';@Injectable()export class ComponentLoaderFactory {  constructor(private _injector: Injector,    private _cfr: ComponentFactoryResolver) {  }  create<T>(): ComponentLoader<T> {    return new ComponentLoader(this._cfr, this._injector);  }}

message service

message service提供显示message的API,代码如下:

import {Injectable,Injector} from '@angular/core';import { ComponentLoaderFactory } from '../component-loader/component-loader.factory';import {MessageComponent} from './message.component';import {ComponentLoader} from '../component-loader/component-loader.class';@Injectable()export class MessageService{  constructor(private _clf:ComponentLoaderFactory,private _injector:Injector){    this.loader=this._clf.create<MessageComponent>();  }  private loader:ComponentLoader<MessageComponent>  private createMessage(t,c,duration=2000){    this.loader.attch(MessageComponent).to('body');    const opts = {      msgType: t,      payload:c    };    const ref = this.loader.create(opts);    ref.changeDetectorRef.markForCheck();    ref.changeDetectorRef.detectChanges();    let self=this;    let st = setTimeout(() => {      self.loader.remove(ref);    }, duration);  }  public info(payload,duration?) {    this.createMessage('info',payload,duration);  }  public success(payload,duration?) {    this.createMessage('success',payload,duration);  }  public error(payload,duration?) {    this.createMessage('error',payload,duration);  }  public warning(payload,duration?) {    this.createMessage('warning',payload,duration);  }}

message.module

最后,增加message.module.ts。记得要把动态创建的组件添加到entryComponents数组中。

import {NgModule} from '@angular/core';import { CommonModule } from '@angular/common';import {MessageComponent} from './message.component';import {MessageService} from './message.service';import {ComponentLoaderFactory} from '../component-loader/component-loader.factory';@NgModule({  imports:[CommonModule],  declarations:[MessageComponent],  providers:[MessageService,ComponentLoaderFactory],  entryComponents:[MessageComponent],  exports:[MessageComponent]})export class MessageModule{}

使用方法

注入MessageService,调用API使用Message组件。

this._msgService.success('成功了!');

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持武林网。

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