加载数据时ProgressBar没有设置动画;并且加载不';使用wait时不要等待
本文关键字:加载 使用 wait 等待 数据 设置 动画 ProgressBar | 更新日期: 2024-10-19 23:03:26
在我的应用程序中,需要从数据库加载数据。在此期间,将显示一个启动屏幕。我想有一个进度条动画,所以把它添加到启动屏幕xaml;
<ProgressBar Margin="5" DockPanel.Dock="Top" IsIndeterminate="True" />
这是可行的,但动画基本上在每次长时间检索数据时停止。我的负载数据如下所示;
private void loadData()
{
getData1FromDB();
displayData1_OnScreen();
getData2FromDB();
displayData2_OnScreen();
getData3FromDB();
displayData3_OnScreen();
}
因此,当getData1FromDB()
正在运行时,进度条动画将停止。认为这个问题可以像;
private async void loadData()
{
await Task.Run(() => getData1FromDB());
displayData1_OnScreen();
getData2FromDB();
await Task.Run(() => displayData2_OnScreen());
getData3FromDB();
await Task.Run(() => displayData3_OnScreen());
}
这引发了另一个问题。当getData1FromDB()
运行时,程序进入displayData1_OnScreen
。由于getData1FromDB()
未完成,因此未显示任何数据。
如何在不重写整个加载过程的情况下解决此问题?
编辑:基于评论;
没有其他东西在呼叫displayData1_OnScreen
,老实说,我也很惊讶。我唯一能想到的是loadData()
是从构造函数调用的。
老实说,不,我不确定这就是问题所在。我正在尝试进行更多的调试,看看@BradleyDotNET提出它后实际发生了什么。
对于getData1FromDB
的问题,这有点难以解决。基本上,它基于参数集构建一个sqlCMD字符串,然后像这样运行它;
DataTable dt = new DataTable();
string ConString = ConnectionString();
using (MySqlConnection con = new MySqlConnection(ConString))
{
MySqlDataAdapter da = new MySqlDataAdapter();
MySqlCommand cmd = new MySqlCommand(sqlCMD, con);
con.Open();
da.SelectCommand = cmd;
da.Fill(dt);
con.Close();
}
return dt;
值得一提的是,即使loadData()在构造函数-中运行,下面的repo尝试似乎也能完成您想要的操作
CS:
using System;
using System.ComponentModel;
using System.Linq.Expressions;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
namespace WpfAsyncAwaitProgressbar
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
DataContext = new TestViewModel();
}
}
public class TestViewModel : INotifyPropertyChanged
{
public TestViewModel()
{
Text1 = Text2 = Text3 = "Loading ...";
loadData();
}
public string Text1 { get; private set; }
public string Text2 { get; private set; }
public string Text3 { get; private set; }
public Visibility ProgressbarVisibility { get; private set; }
private async void loadData()
{
setBusyMode(true);
await Task.Run(() => getData1FromDB());
await Task.Run(() => getData2FromDB());
await Task.Run(() => getData3FromDB());
setBusyMode(false);
}
private void getData1FromDB()
{
Thread.Sleep(3000);
Text1 = "Data Result 1";
raisePropertyChanged(() => Text1);
}
private void getData2FromDB()
{
Thread.Sleep(2000);
Text2 = "Data Result 2";
raisePropertyChanged(() => Text2);
}
private void getData3FromDB()
{
Thread.Sleep(1000);
Text3 = "Data Result 3";
raisePropertyChanged(() => Text3);
}
private void setBusyMode(bool isBusy)
{
ProgressbarVisibility = isBusy ? Visibility.Visible : Visibility.Hidden;
raisePropertyChanged(() => ProgressbarVisibility);
}
#region INotifyPropertyChanged
public event PropertyChangedEventHandler PropertyChanged;
protected void raisePropertyChanged<TProperty>(Expression<Func<TProperty>> projection)
{
var memberExpression = (MemberExpression)projection.Body;
raisePropertyChanged(memberExpression.Member.Name);
}
private void raisePropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#endregion INotifyPropertyChanged
}
}
XAML:
<Window x:Class="WpfAsyncAwaitProgressbar.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" SizeToContent="WidthAndHeight">
<StackPanel>
<TextBlock Text="{Binding Text1}"/>
<TextBlock Text="{Binding Text2}"/>
<TextBlock Text="{Binding Text3}"/>
<ProgressBar Visibility="{Binding ProgressbarVisibility}"
IsIndeterminate="True"
Height="10"/>
</StackPanel>
</Window>
-
除事件处理程序外,不应使用async void:http://channel9.msdn.com/Series/Three-Essential-Tips-for-Async/Tip-1-Async-void-is-for-top-level-event-handlers-only
-
wpf中有一些动画,即使UI线程被阻止,也可以在图形卡上运行,但它们非常有限,我不相信
这个代码怎么样?
private async Task loadData()
{
await Task.Run(getData1FromDB);
displayData1_OnScreen();
await Task.Run(getData2FromDB);
displayData2_OnScreen();
await Task.Run(getData3FromDB);
displayData3_OnScreen();
}