WPF学习之路（九）导航和页面（续）

生命周期

如果Page1成功导航到Page2，首先会触发NavigationService的Navigating事件，标识导航开始。随后创建Page2对象，并且触发NavigationProgress事件。该事件用于提供导航进度信息，每次返回1KB数据就会引发该事件。随后触发Navigated事件，LoadCompleted紧随其后，这时表明页面已经下载完毕。Page1触发UnLoaded事件，宣告其结束。Page2触发Loaded事件，表明其开始。

实例(取自《葵花宝典--WPF自学手册》)

App.xaml

<Application x:Class="Alex_WPFAPPDemo07.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             Navigating="Application_Navigating"
             NavigationFailed="Application_NavigationFailed"
             Navigated="Application_Navigated"
             NavigationProgress="Application_NavigationProgress"
             NavigationStopped="Application_NavigationStopped"
             LoadCompleted="Application_LoadCompleted"
             FragmentNavigation="Application_FragmentNavigation"
             StartupUri="CustomPage.xaml">
    <Application.Resources>
        <Style TargetType="TextBlock">
            <Setter Property="FontSize" Value="" />
            <Setter Property="Margin" Value="" />
        </Style>
    </Application.Resources>
</Application>

App.xaml.cs

public partial class App : Application
{
    private void Application_Navigating(object sender, System.Windows.Navigation.NavigatingCancelEventArgs e)
    {
        System.Console.WriteLine("------------------------------------------");
        System.Console.Write("触发的事件为：Application_Navigating\n");
        System.Console.WriteLine("导航页面的Uri:" + e.Uri.ToString());
    }

    private void Application_NavigationFailed(object sender, System.Windows.Navigation.NavigationFailedEventArgs e)
    {
        System.Console.WriteLine("------------------------------------------");
        System.Console.Write("触发的事件为：Application_NavigationFailed\n");
        System.Console.WriteLine("失败的异常是: " + e.Exception.ToString());
        // Handled属性设置为true，从而防止异常继续上传转变为一个未处理的应用程序异常
        e.Handled = true;
    }

    private void Application_Navigated(object sender, System.Windows.Navigation.NavigationEventArgs e)
    {
        System.Console.WriteLine("------------------------------------------");
        System.Console.Write("触发的事件为：Application_Navigated\n");
        System.Console.WriteLine("导航页面的Uri:" + e.Uri.ToString());
    }

    private void Application_NavigationProgress(object sender, System.Windows.Navigation.NavigationProgressEventArgs e)
    {
        System.Console.WriteLine("------------------------------------------");
        System.Console.Write("触发的事件为：Application_NavigationProgress\n");
        System.Console.WriteLine("导航页面的Uri:" + e.Uri.ToString());
        System.Console.WriteLine("已经得到的字节数为{0}", e.BytesRead);
    }

    private void Application_NavigationStopped(object sender, System.Windows.Navigation.NavigationEventArgs e)
    {
        System.Console.WriteLine("------------------------------------------");
        System.Console.Write("触发的事件为：Application_NavigationStopped\n");
        System.Console.WriteLine("导航页面的Uri:" + e.Uri.ToString());
    }

    private void Application_LoadCompleted(object sender, System.Windows.Navigation.NavigationEventArgs e)
    {
        System.Console.WriteLine("------------------------------------------");
        System.Console.Write("触发的事件为：Application_LoadCompleted\n");
        System.Console.WriteLine("导航页面的Uri:" + e.Uri.ToString());
    }

    private void Application_FragmentNavigation(object sender, System.Windows.Navigation.FragmentNavigationEventArgs e)
    {
        System.Console.WriteLine("------------------------------------------");
        System.Console.Write("触发的事件为：Application_FragmentNavigation\n");
        System.Console.WriteLine("导航的段落为:" + e.Fragment);
    }
}

修改工程的Output type属性

效果如下图

在控制台输出中可以看到导航的整个过程都经过了哪些事件的处理

To be continue...