angular中的服务和持久化实现

1.创建服务：

ng g service my-new-service
创建到指定目录下面
ng g service services/storage

编写storage.service.ts代码：

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

@Injectable({
  providedIn: 'root'
})
export class StorageService {

  constructor() { }

  set(key,value){
    localStorage.setItem(key,JSON.stringify(value));
  }
  get(key){
    return JSON.parse(localStorage.getItem(key));
  }
  remove(key){
    localStorage.removeItem(key);
  }
}

2.app.module.ts 里面引入创建的服务

import { StorageService } from './services/storage.service';

NgModule 里面的 providers 里面依赖注入服务
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { HomeComponent } from './components/home/home.component';
import { StorageService } from './services/storage.service';
@NgModule({
  declarations: [
    AppComponent,
    HomeComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    AppRoutingModule
  ],
  providers: [StorageService],
  bootstrap: [AppComponent]
})
export class AppModule { }

3.使用的页面引入服务，注册服务

import { Component } from '@angular/core';
import { StorageService } from './services/storage.service';
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})

export class AppComponent {
  constructor(private storage : StorageService){

  }
  title = 'angulardemo';

  key= 1
  name='张三';
  list:any=[]

  addData(){
    // alert(this.username);
    this.list.push(this.name);
    this.storage.set('todolist',this.list);
 }
 removerData(key){
      console.log(key);
      this.list.splice(key,1);
      this.storage.set('todolist',this.list);
}
}

页面设计

<div style="text-align:center">
  <h1>
    Welcome to {{ title }}!
  </h1>
  <input [(ngModel)]="name">
 <button (click)="addData()">添加数据</button>
 <button (click)="removerData(key)">删除数据</button>

效果：