【上位机——WPF】App.xml和Application类简介

概述

xaml类型的文件包含两部分，一部分以.xaml扩展名结尾的前端代码，另一部分以.xaml.cs结尾的后端代码，通常我们也把后端代码称为隐藏代码。

App.xaml

<Application x:Class="WpfDemo1.App"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:local="clr-namespace:WpfDemo1"StartupUri="MainWindow.xaml"><Application.Resources><!--这里编写一些资源 通用样式--></Application.Resources>
</Application>

x:Class=“WpfDemo1.App” :指的是App.xaml.cs文件中的App类
xmlns:local=“clr-namespace:WpfDemo1” :指的是本地的命名空间(也是项目名)
StartupUri=“MainWindow.xaml”:指定程序要启动的窗口

App.xaml.cs

using System.Configuration;
using System.Data;
using System.Windows;namespace WpfDemo1
{/// <summary>/// Interaction logic for App.xaml/// </summary>public partial class App : Application{}}Application:继承了所有控件的祖先

入门代码

App.xaml

<Application x:Class="WpfDemo1.App"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:local="clr-namespace:WpfDemo1"StartupUri="MainWindow.xaml"><Application.Resources><ResourceDictionary><!--定义Button按钮前景色为红色--><Style TargetType="Button" x:Key="ButtonStyle"><Setter Property="Foreground" Value="Red"></Setter></Style></ResourceDictionary></Application.Resources>
</Application>

MainWindow.xml

<Window x:Class="WpfDemo1.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:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"xmlns:local="clr-namespace:WpfDemo1"mc:Ignorable="d"Title="MainWindow" Height="450" Width="800"><Grid><!--Style 加载的是App.xaml文件中的Style标签 key为ButtonStyle的样式--><Button Content="Hello world" Width="200" Height="40"  Style="{StaticResource ButtonStyle}"></Button></Grid>
</Window>

Application生命周期

using System.Configuration;
using System.Data;
using System.Windows;namespace WpfDemo1
{/// <summary>/// Interaction logic for App.xaml/// </summary>public partial class App : Application{/// <summary>/// 应用程序启动时，做一些初始化的工作/// </summary>/// <param name="e"></param>protected override void OnStartup(StartupEventArgs e){base.OnStartup(e);}/// <summary>/// 当应用程序结束时/// </summary>/// <param name="e"></param>protected override void OnExit(ExitEventArgs e){base.OnExit(e);}/// <summary>/// 当应用程序被激活时/// </summary>/// <param name="e"></param>protected override void OnActivated(EventArgs e){base.OnActivated(e);}/// <summary>/// 当应用程序处于非激活状态/// </summary>/// <param name="e"></param>protected override void OnDeactivated(EventArgs e){base.OnDeactivated(e);}}}

窗体的声明周期

using System.Text;
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 WpfDemo1
{/// <summary>/// Interaction logic for MainWindow.xaml/// </summary>public partial class MainWindow : Window{public MainWindow(){InitializeComponent();//创建窗体源时引发此事件 比load还要提前this.SourceInitialized += (o, e) => {Console.WriteLine("SourceInitialized");};//窗体加载时引发此事件this.Loaded += (o, e) => {Console.WriteLine("Loaded");};//窗体被激活引发此事件this.Activated += (o, e) => {Console.WriteLine("Activated");};//窗体非激活引发此事件this.Deactivated += (o, e) => {Console.WriteLine("Deactivated");};//释放资源引发此事件this.Unloaded += (o, e) => { Console.WriteLine("Unloaded"); };this.Closing += (o, e) => { Console.WriteLine("Closing"); };this.Closed += (o, e) => { Console.WriteLine("Closed"); };//渲染页面this.ContentRendered += (o, e) => { Console.WriteLine("ContentRendered"); };//等同于//this.ContentRendered += OnContentRendered;}private void OnContentRendered(object sender,EventArgs e) {Console.WriteLine("ContentRendered");}}
}