使用CancellationTokenSource来控制长时间sql查询中断

前端

  <!-- 透明的覆盖层，显示在页面上方，包含进度条 -->
  <Grid Visibility="{Binding IsLoading}" 
Background="Transparent" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" ZIndex="1">
      <Grid.InputBindings>
          <MouseBinding Gesture="LeftDoubleClick" Command="{Binding CancelTaskCommand}" />
      </Grid.InputBindings>
      <Border Background="Black" Opacity="0.5" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
          <!-- 使用 StackPanel 垂直排列进度条和文本 -->
          <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" Margin="0, 50, 0, 0">
              <!-- 进度条居中显示 -->
              <ProgressBar x:Name="LoadingProgressBar"
                   IsIndeterminate="True"
                   Height="50" 
                   Width="200" 
                   HorizontalAlignment="Center"
                   VerticalAlignment="Center" 
                   Margin="0, 0, 0, 0"  
                   MouseDoubleClick="LoadingProgressBar_MouseDoubleClick"/>

              <!-- 显示的文字 -->
              <TextBlock Text="双击屏幕取消查询"
                 HorizontalAlignment="Center"
                 Foreground="White"
                 FontSize="30"
                 VerticalAlignment="Center"/>
          </StackPanel>
      </Border>
  </Grid>

后端代码

 private void LoadingProgressBar_MouseDoubleClick(object sender, MouseButtonEventArgs e)
 {
     viewModel.CancelTaskCommand.Execute(null);

 }

viewModel代码

 [RelayCommand]
 private  async void SelectInfo()
 {

     try
     {

         string sql = "..........";
        
         ChangeLoadingStatus(true);//进入加载状态

         // 创建 CancellationTokenSource，并获取 CancellationToken
         _cancellationTokenSource = new CancellationTokenSource();
         var token = _cancellationTokenSource.Token;

         // 启动异步任务，并传递 token
         List<ToolStr50> result = await Task.Run(() => ExecuteQueryWithCancellation(sql, token), token); 

         ChangeLoadingStatus(false);//结束加载状态

         TaxinclusiveSum = "合计含税金额:0";
         InfoCount = "数据汇总:0条";
      
     }
     catch (OperationCanceledException ex)
     {
         ChangeLoadingStatus(false);//结束加载状态
         Notification.Error(ex.Message, millisecondTimeOut: 2200);
     }
     catch (Exception ex)
     {
         ChangeLoadingStatus(false);//结束加载状态
         Notification.Error("系统异常-" + ex.Message, millisecondTimeOut: 2200);

     }
 }

 private async Task<List<ToolStr50>> ExecuteQueryWithCancellation(string sql, CancellationToken token)
 {
     try
     {
         // 直接传递 CancellationToken 到数据库查询
         return await dal.db.SqlQueryable<ToolStr50>(sql)
                             .ToListAsync(token);  // 将 token 传递给 ToListAsync
     }
     catch (OperationCanceledException)
     {
         // 如果任务被取消，处理取消逻辑
         throw new OperationCanceledException("查询已取消", null, token);
     }
 }



 [RelayCommand]
 // 取消任务的方法
 public void CancelTask()
 {
     _cancellationTokenSource?.Cancel(); // 请求取消
 }