为了实现您的需要,您需要扩展一些将用作视图的根容器的 ViewGroup。让我们从这个开始:
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对我们来说是一个技巧。
然后在一些 xml 中使用它(我将其称为 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(尽管我想您知道如何做到这一点,但为了完整起见,我无论如何都会发布它):
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 公开了一个侦听器接口,我们的服务需要实现该接口并将其自身订阅到布局。
另请记住,这解决了处理后退按钮的问题。要处理主页按钮,您可能需要看看https://stackoverflow.com/a/31340960 https://stackoverflow.com/a/31340960 and https://stackoverflow.com/a/33580971 https://stackoverflow.com/a/33580971- 基本上我的答案是这两个链接的一些总结+https://stackoverflow.com/a/15980900 https://stackoverflow.com/a/15980900但包含一些调整(例如,您不能在 WindowManager.LayoutParams 中设置 FLAG_NOT_FOCUSABLE)。
当然,您需要通过调用startService在某个地方启动您的服务,在AndroidManifest.xml中声明该服务并添加SYSTEM_ALERT_WINDOW权限。