创建服务

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

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

@NgModule({ 
declarations: [ AppComponent, HeaderComponent, FooterComponent, NewsComponent, TodolistComponent ],
imports: [ BrowserModule, FormsModule ],
providers: [StorageService], //注入服务
bootstrap: [AppComponent] 
})
export class AppModule { }

使用的页面引入服务，注册服务

import { StorageService } from '../../services/storage.service';
constructor(private storage: StorageService) { }

使用

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

/*
1、ng g service services/storag
2、app.module.ts 里面引入创建的服务 并且声明
import { StorageService } from './services/storage.service'
providers: [StorageService]
3、在用到的组件里面
      //引入服务
      import { StorageService } from '../../services/storage.service';
      //初始化
      constructor(public storage:StorageService) { 
          let s=this.storage.get();
          console.log(s);
      }
*/
import { Component, OnInit } from '@angular/core';
//引入服务
import { StorageService } from '../../services/storage.service';
/*
不推荐
var storage=new StorageService();
console.log(storage);
*/
@Component({
  selector: 'app-search',
  templateUrl: './search.component.html',
  styleUrls: ['./search.component.scss']
})
export class SearchComponent implements OnInit {
  public keyword:string;
  public historyList:any[]=[];
  constructor(public storage:StorageService) { 
  }
  ngOnInit() {
    console.log('页面刷新会触发这个生命周期函数');
    var searchlist:any=this.storage.get('searchlist');
    if(searchlist){
      this.historyList=searchlist;        
    }
  }
  doSearch(){
    if(this.historyList.indexOf(this.keyword)==-1){
      this.historyList.push(this.keyword);
      this.storage.set('searchlist',this.historyList);
    }    
    this.keyword='';    
  }
  deleteHistroy(key){
      this.historyList.splice(key,1);
      this.storage.set('searchlist',this.historyList);
  }
}