如何从信使聊天头服务等服务中检测后门按钮/主页按键？

public class BackButtonAwareLinearLayout extends LinearLayout {

    public interface BackButtonListener {
        void onBackButtonPressed();
    }

    @Nullable
    private BackButtonListener mListener;

    public BackButtonAwareLinearLayout(Context context) {
        super(context);
    }

    public BackButtonAwareLinearLayout(Context context,AttributeSet attrs) {
        super(context,attrs);
    }

    public BackButtonAwareLinearLayout(Context context,AttributeSet attrs,int defStyleAttr) {
        super(context,attrs,defStyleAttr);
    }

    public void setBackButtonListener(@Nullable BackButtonListener listener) {
        mListener = listener;
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if (event != null && event.getKeyCode() == KeyEvent.KEYCODE_BACK
                && mListener != null) {
            mListener.onBackButtonPressed();
            return true;
        }
        return super.dispatchKeyEvent(event);
    }
}

基本上,重写dispatchKeyEvent对我们来说是一个诀窍.
然后在一些xml中使用它(我称之为chat_head_container.xml)：

<?xml version="1.0" encoding="utf-8"?>
<com.pablo432.myapplication.BackButtonAwareLinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="48sp"
        android:text="Hello,world!"
        android:textColor="#000"
        android:background="#f5f5f5"
        android:gravity="center"/>

</com.pablo432.myapplication.BackButtonAwareLinearLayout>

接下来,创建一个将我们的视图添加到WindowManager的服务(虽然我想你知道如何去做,但为了完整起见我还是会发布它)：

public class ChatHeadService extends Service
        implements BackButtonAwareLinearLayout.BackButtonListener {

    private WindowManager mWindowManager;
    private BackButtonAwareLinearLayout mRootContainer;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mRootContainer = (BackButtonAwareLinearLayout) inflater.inflate(
                R.layout.chat_head_container,null,false);
        mRootContainer.setBackButtonListener(this);

        WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.MATCH_PARENT,WindowManager.LayoutParams.MATCH_PARENT,WindowManager.LayoutParams.TYPE_PHONE,WindowManager.LayoutParams.FLAG_FULLSCREEN,PixelFormat.TRANSPARENT);

        mWindowManager.addView(mRootContainer,layoutParams);
    }

    @Override
    public void onBackButtonPressed() {
        mRootContainer.setBackButtonListener(null);
        mWindowManager.removeView(mRootContainer);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mRootContainer != null) mWindowManager.removeView(mRootContainer);
    }
}

长话短说,BackButtonAwareLinearLayout公开了一个监听器接口,我们的服务需要实现并订阅自己的布局.

还要记住,这个地址处理后退按钮.要处理主页按钮,您可能需要查看https://stackoverflow.com/a/31340960和https://stackoverflow.com/a/33580971 – 基本上我的答案是来自这两个链接https://stackoverflow.com/a/15980900的一些摘要,但包含一些调整(例如,您不能在WindowManager中设置FLAG_NOT_FOCUSABLE.的LayoutParams).

当然,您需要通过调用startService在某处启动服务,在AndroidManifest.xml中声明此服务并添加SYSTEM_ALERT_WINDOW权限.