Angular二級導航欄

1,將菜單放入數據庫：
模擬放到該路徑下：
src/assets/json/header.json

{
    "siteName": "PGG娛樂健身中心",
    "menu":[
      {
        "id":"1",
        "menuName":"首頁",
        "menuChildren": [{}],
        "showSubMenu": false
      },
      {
        "id":"2",
        "menuName":"健身中心",
        "menuChildren": [
          {
            "itemId": "1",
            "menuChidrenItem": "居室器械健身"
          },
          {
            "itemId": "2",
            "menuChidrenItem": "野外運動"
          },
          {
            "itemId": "3",
            "menuChidrenItem": "健身小知識"
          }
        ],
        "showSubMenu": false
      },
      {
        "id":"3",
        "menuName":"休閒娛樂",
        "menuChildren": [
          {
            "itemId": "1",
            "menuChidrenItem": "養生釣魚"
          },
          {
            "itemId": "2",
            "menuChidrenItem": "野炊燒烤"
          },
          {
            "itemId": "3",
            "menuChidrenItem": "真人野戰"
          }
        ],
        "showSubMenu": false
      },
      {
        "id":"4",
        "menuName":"訂單中心",
        "menuChildren": [
          {
          "itemId": "1",
          "menuChidrenItem": "所有訂單"
        },
          {
            "itemId": "2",
            "menuChidrenItem": "已完成訂單"
          },
          {
            "itemId": "3",
            "menuChidrenItem": "未完成訂單"
          }
        ],
        "showSubMenu": false
      },
      {
        "id":"5",
        "menuName":"個人中心",
        "menuChildren": [
          {
            "itemId": "1",
            "menuChidrenItem": "用戶信息修改"
          }
        ],
        "showSubMenu": false
      }
    ]
}

ts接受數據，並處理：

import { Component, OnInit } from '@angular/core';
import { HttpClient, HttpClientModule } from '@angular/common/http';

@Component({
  selector: 'app-header',
  templateUrl: './header.component.html',
  styleUrls: ['./header.component.css']
})
export class HeaderComponent implements OnInit {

  headData: any;
  constructor(
    private http: HttpClient
  ) { }

  ngOnInit(): void {
    // http://localhost:4200/assets/json/header.json 可訪問
    this.http.get('/assets/json/header.json').subscribe(data => {
      this.headData = data;
      console.log(this.headData.menu);
    });
  }
  showSubMenu(item: any, index: any): void {
    // 設置當前子菜單顯示
    item.showSubMenu = true;
  }
  notShowSubMenu(item: any, index: any): void {
    // 設置當前子菜單不顯示
    item.showSubMenu = false;
  }
}

html顯示控制，利用ngstyle控制:

<div class="menu_container">
  <div id="top_title">{{headData.siteName}}</div>
  <div id="menu" *ngFor="let item of headData.menu, let i = index">
  <!-- 第一個參數爲類名稱，第二個參數爲boolean值，如果爲true就添加第一個參數的類-->
    <ul [ngClass]="{'sumMenu': item.showSubMenu}">
      <!--mouseleave mouseout供選則-->
      <li class="top_nav nav_1" (mouseenter)="showSubMenu(item ,i)" (mouseleave)="notShowSubMenu(item, i)">
        <span>{{item.menuName}}</span>
        <dl *ngFor="let child of item.menuChildren, let k = index"
            [ngStyle]="{'display': item.showSubMenu ? 'block':'none','margin-left': '-2.6rem'}">
          <dd>{{child.menuChidrenItem}}</dd>
        </dl>
      </li>
    </ul>
  </div>
</div>

實際效果：