发布：2021/10/25 11:18:34作者：管理员 来源：本站 浏览次数：1107
1.介绍
项目中，有个需求是监听手机音量按键，并在ContentPage页面进行事件处理。
2.解决方案
1.新建事件发送者
新建 MyKeyEventPublish.cs ，代码如下
public class MyKeyEventPublish
{
//全局静态变量，以便在需要监听时使用
public static MyKeyEventPublish myKeyEventPublish { get; set; }
public delegate void OnKeyDown_callback(int keyCode);
public OnKeyDown_callback cb;
public Action<int> OnKeyDown { set; get; }
}
2.App.cs
public App(MyKeyEventPublish myKeyEventPublish)
{
InitializeComponent();
//监听手机按键
MyKeyEventPublish.myKeyEventPublish = myKeyEventPublish;
//起始页
MainPage = new NavigationPage(new Login());
}
3.MainActivity.cs (Android)
//按键事件发布者
MyKeyEventPublish myKeyEventPublish;
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
//实例化按键发布者
myKeyEventPublish = new MyKeyEventPublish();
base.OnCreate(savedInstanceState);
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
LoadApplication(new App(myKeyEventPublish));
}
//监听键盘按下
public override bool OnKeyDown([GeneratedEnum]Keycode keyCode, KeyEvent e)
{
if (keyCode == Android.Views.Keycode.Back) {
return base.OnKeyDown(keyCode,e);
}
if (myKeyEventPublish == null || myKeyEventPublish.OnKeyDown == null) return true;
//键值更改事件发布方法
myKeyEventPublish.OnKeyDown((int)keyCode);
return true;
//return base.OnKeyDown(keyCode, e); //不屏蔽原有功能
}
4.ContentPage.cs 页面使用
public Login()
{
InitializeComponent();
NavigationPage.SetHasNavigationBar(this, false);
this.Appearing += Login_Appearing;
this.Disappearing += Login_Disappearing;
}
//页面销毁
private void Login_Disappearing(object sender, EventArgs e)
{
MyKeyEventPublish.myKeyEventPublish.OnKeyDown -= OnKeyDownCallBack;
}
//页面显示
private void Login_Appearing(object sender, EventArgs e)
{
MyKeyEventPublish.myKeyEventPublish.OnKeyDown += OnKeyDownCallBack;
}
//这个是处理函数
void OnKeyDownCallBack(int keyCode)
{
Console.WriteLine("keycode:" + keyCode);
}
以上是全部代码，如有问题，请及时评论！我会一一解答！请多多点赞哦！
