下面是一个使用Angular Material mat-tree和复选框实现全选功能的示例代码：

首先，需要在你的app.module.ts文件中导入MatCheckboxModule和MatTreeModule：

import { MatTreeModule } from '@angular/material/tree';
import { MatCheckboxModule } from '@angular/material/checkbox';

@NgModule({
  imports: [
    MatTreeModule,
    MatCheckboxModule
  ],
  ...
})
export class AppModule { }

然后，在你的组件的HTML模板文件中使用mat-tree和mat-checkbox来展示树状结构和复选框：

  
    {{node.name}}
  

  
    

      
        
          {{treeControl.isExpanded(node) ? 'expand_more' : 'chevron_right'}}
        
      
      {{node.name}}
    
    

      
    
  

在组件的Typescript文件中，需要定义数据源和树控制器，并添加一些辅助方法来实现全选功能：

import { Component } from '@angular/core';
import { MatTreeNestedDataSource } from '@angular/material/tree';
import { NestedTreeControl } from '@angular/cdk/tree';

interface TreeNode {
  name: string;
  children?: TreeNode[];
  checked?: boolean;
}

@Component({
  selector: 'app-tree',
  templateUrl: 'tree.component.html',
  styleUrls: ['tree.component.css']
})
export class TreeComponent {
  dataSource = new MatTreeNestedDataSource();
  treeControl = new NestedTreeControl(node => node.children);

  constructor() {
    // 设置树的数据源
    this.dataSource.data = [
      {
        name: 'Node 1',
        children: [
          {
            name: 'Child 1',
            children: [
              { name: 'Grandchild 1' },
              { name: 'Grandchild 2' },
              { name: 'Grandchild 3' }
            ]
          },
          {
            name: 'Child 2',
            children: [
              { name: 'Grandchild 4' },
              { name: 'Grandchild 5' },
              { name: 'Grandchild 6' }
            ]
          }
        ]
      },
      {
        name: 'Node 2',
        children: [
          {
            name: 'Child 3',
            children: [
              { name: 'Grandchild 7' },
              { name: 'Grandchild 8' },
              { name: 'Grandchild 9' }
            ]
          },
          {
            name: 'Child 4',
            children: [
              { name: 'Grandchild 10' },
              { name: 'Grandchild 11' },
              { name: 'Grandchild 12' }
            ]
          }
        ]
      }
    ];
  }

  hasChild(_: number, node: TreeNode): boolean {
    return !!node.children && node.children.length > 0;
  }

  checkAllParents(node: TreeNode) {
    const parent = this.getParentNode(node);
    if (parent) {
      this.checkAllParents(parent);
    }
    this.checkChildren(node);
  }

  checkChildren(node: TreeNode) {
    node.checked = !node.checked;
    if (node.children) {
      node.children.forEach(child => {
        this.checkChildren(child);
      });
    }
  }

  getParentNode(node: TreeNode): TreeNode | null {
    const currentLevel = this.getLevel(node);

    if (currentLevel < 1) {
      return null;
    }

    const startIndex = this.treeControl.dataNodes.indexOf(node) - 1;

    for (let i = startIndex; i >= 0; i--) {
      const currentNode = this.treeControl.dataNodes[i];
      if (this.getLevel(currentNode) < currentLevel) {
        return currentNode;
      }
    }
    return