具有可展开行的角材料表，在stackBlitz示例中更改选项卡时自动展开

<mat-accordion #accordion>
  <mat-expansion-panel *ngFor="let item of items">
    <!-- 行内容 -->
  </mat-expansion-panel>
</mat-accordion>

import { Component, ViewChild, AfterViewInit } from '@angular/core';
import { MatAccordion } from '@angular/material/expansion';

@Component({
  selector: 'app-your-component',
  templateUrl: './your-component.component.html',
  styleUrls: ['./your-component.component.css']
})
export class YourComponent implements AfterViewInit {
  @ViewChild('accordion') accordion: MatAccordion;

  // 其他组件代码

  ngAfterViewInit() {
    // 在选项卡更改时自动展开行
    this.tabGroup.selectedIndexChange.subscribe(index => {
      this.accordion.openAll();
    });
  }
}