1. 创建一个名为 LocalStorageService 的服务：

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

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

  constructor() { }

  public setItem(key: string, value: any): void {
    localStorage.setItem(key, JSON.stringify(value));
  }

  public getItem(key: string): any {
    const item = localStorage.getItem(key);
    return item ? JSON.parse(item) : null;
  }

  public removeItem(key: string): void {
    localStorage.removeItem(key);
  }

  public clear(): void {
    localStorage.clear();
  }

}

2. 在组件中使用 LocalStorageService

例如，我们要在组件中存储一个布尔值：

import { Component } from '@angular/core';
import { LocalStorageService } from './local-storage.service';

@Component({
  selector: 'app-my-component',
  template: `
    Toggle setting
    
Setting value: {{ settingValue }}
  `
})
export class MyComponent {

  settingKey = 'my-setting';
  settingValue = false;

  constructor(private localStorageService: LocalStorageService) {
    const storedValue = this.localStorageService.getItem(this.settingKey);
    if (storedValue !== null) {
      this.settingValue = storedValue;
    }
  }

  toggleSetting(): void {
    this.settingValue = !this.settingValue;
    this.localStorageService.setItem(this.settingKey, this.settingValue);
  }

}

这样就可以使用 LocalStorageService 在本地存储中读写用户设置了。