Wpf 異步方法更新進度條

前面用了Background方法來更新進度條，這次用更好用異步方法來更新進度條

先看效果

 

cs代碼

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace Wpf中的異步操作
{
    /// <summary>
    /// MainWindow.xaml 的交互邏輯
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            Update();
        }

        private async void Button_Click1(object sender, RoutedEventArgs e)
        {
            text.Text = "0";
            var result = await UpdateAsync();//等待方法完成
            text.Text = result.ToString();
            MessageBox.Show("異步方法完成后");//在方法完成后輸出
        }

        private void Button_Click2(object sender, RoutedEventArgs e)
        {
            text.Text = "0";
            UpdateAsync().ContinueWith(t =>
            {
                //UI線程調用更新文字
                Dispatcher.Invoke(() =>
                {
                    text.Text = t.Result.ToString();
                });
                MessageBox.Show("異步方法完成后");
            });//沒有等待，繼續往下執行

            MessageBox.Show("異步方法完成前");//在方法完成前輸出
        }

        /// <summary>
        /// 同步方法更新進度條
        /// </summary>
        private void Update()
        {
            for (int i = 0; i < 100; i++)
            {
                Thread.Sleep(50);
                bar.Value = i + 1;
            }
        }

        /// <summary>
        /// 異步方法更新進度條
        /// </summary>
        /// <returns></returns>
        private async Task<int> UpdateAsync()
        {
            var num = 0;
            for (int i = 0; i < 100; i++)
            {
                await Task.Delay(50);//等待
                bar.Value = i + 1;
                num += i;
            }
            return num;
        }
    }
}

xaml代碼

<Window
    x:Class="Wpf中的異步操作.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:local="clr-namespace:Wpf中的異步操作"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Title="MainWindow"
    Width="800"
    Height="450"
    mc:Ignorable="d">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <StackPanel Orientation="Vertical">
            <Button
                Width="200"
                Height="50"
                Click="Button_Click"
                Content="同步方法" />
            <Button
                Width="200"
                Height="50"
                Click="Button_Click1"
                Content="異步方法1" />
            <Button
                Width="200"
                Height="50"
                Click="Button_Click2"
                Content="異步方法2" />
            <TextBlock
                HorizontalAlignment="Center"
                FontSize="50"
                Text="{Binding Path=Value, ElementName=bar}" />
            <ProgressBar x:Name="bar" Height="50" />
            <TextBlock
                x:Name="text"
                HorizontalAlignment="Center"
                FontSize="50"
                Text="0" />
        </StackPanel>
    </Grid>
</Window>