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 tokenList<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})
