動手寫一個angular版本的Message組件的方法

更新時間：2017年12月16日 09:36:58 作者：木易木啊

本篇文章主要介紹了動手寫一個angular版本的Message組件的方法，小編覺得挺不錯的，現(xiàn)在分享給大家，也給大家做個參考。一起跟隨小編過來看看吧

學習一個框架或庫的最好方法是看官方文檔，并著手去寫例子。最近在利用空閑的時間學習angular，那今天就嘗試寫一個message組件，并通過message服務(wù)動態(tài)加載message組件。
我所參與的項目基本是用jquery完成的。之前，在項目中自己動手寫過一個簡單的message插件，樣子如下圖。

那現(xiàn)在就使用angular（版本5.0.0）來實現(xiàn)message組件。

message組件

message組件要根據(jù)傳入的類型、消息和duration來顯示。創(chuàng)建三個文件：message.component.ts,message.component.html,message.component.css，代碼如下。

//message.component.ts
import {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

通過官方文檔動態(tài)組件一節(jié)，可以了解動態(tài)創(chuàng)建組件需要通過ComponentFactoryResolver來完成。使用ComponentFactoryResolver創(chuàng)建ComponentFactory，再通過ComponentFactory的create方法創(chuàng)建組件?？垂俜轿臋n中API的說明，ComponentFactory的create方法至少需要一個injector參數(shù)，而injector的創(chuàng)建在文檔中也有提到，其中參數(shù)providers為需要注入的類。再梳理下整個過程：

提供providers
創(chuàng)建Injector實例
創(chuàng)建ComponetFactory
使用ComponetFactory創(chuàng)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創(chuàng)建injector實例
static create(providers: StaticProvider[], parent?: Injector): Injector

為了代碼的復用，這里創(chuàng)建通用的loader類來完成組件的動態(tài)創(chuàng)建。其中，attch方法用于初始化ComponetFactory（參數(shù)為組件類型）；to方法用于標識組件的父容器；provider方法用于初始化可注入的類；create方法用于創(chuàng)建組件并手動變更檢測；remove方法用于移除組件。

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;
  }
}

同時，為了便于loader的創(chuàng)建，再創(chuàng)建LoaderFactory類，代碼如下：

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提供顯示message的API，代碼如下：

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。記得要把動態(tài)創(chuàng)建的組件添加到entryComponents數(shù)組中。

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，調(diào)用API使用Message組件。