动手写一个angular版本的Message组件的方法

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.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

通过官方文档一节，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。