Xamarin.Forms Android PDA 监听手机按键

资料来源：网络整理时间：2023/2/14 0:56:42 共计：3586 浏览

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！

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