Android 始终在顶部布局不起作用

我想在顶部创建一个图层，这样它就会出现在你能看到的每一个页面上（所有应用程序和…），如下图所示：

它在ide（android studio）中没有错误，但它不工作，它只显示一个没有视图的白色屏幕，在logcat中可以看到下面的错误

E/art:pid 18140的setrlimit（RLIMIT_CORE）失败：不允许操作

清单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.tpck.myapp">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">

<meta-data
    android:name="com.google.android.gms.version"
    android:value="@integer/google_play_services_version" />

<activity android:name=".AAA"
    android:exported="true">

    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>

</activity>

<service
    android:name="HUD"
    android:exported="false"
   />
</application>

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

</manifest>

服务

package com.tpck.myapp;

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Toast;

public class HUD extends Service {
HUDView mView;

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

@Override
public void onCreate() {
super.onCreate();

Toast.makeText(getBaseContext(),"onCreate",    Toast.LENGTH_LONG).show();
mView = new HUDView(this);
WindowManager.LayoutParams params = new WindowManager.LayoutParams(

        WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
        WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
        PixelFormat.TRANSLUCENT);
        params.gravity = Gravity.RIGHT | Gravity.TOP;
        params.setTitle("Load Average");
 WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
wm.addView(mView, params);
}

@Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(getBaseContext(),"onDestroy", Toast.LENGTH_LONG).show();
if(mView != null)
{
    ((WindowManager) getSystemService(WINDOW_SERVICE)).removeView(mView);
    mView = null;
}
    }
}

class HUDView extends ViewGroup {
private Paint mLoadPaint;

public HUDView(Context context) {
super(context);
Toast.makeText(getContext(),"HUDView", Toast.LENGTH_LONG).show();

mLoadPaint = new Paint();
mLoadPaint.setAntiAlias(true);
mLoadPaint.setTextSize(10);
mLoadPaint.setARGB(255, 255, 0, 0);
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawText("Hello World", 5, 15, mLoadPaint);
}

@Override
protected void onLayout(boolean arg0, int arg1, int arg2, int arg3,    int     arg4) {
}

@Override
public boolean onTouchEvent(MotionEvent event) {


Toast.makeText(getContext(),"onTouchEvent", Toast.LENGTH_LONG).show();
return true;
    }
}

---

看一看。这个库正是您想要的。

哦，我明白了……您希望您的窗口始终显示在所有其他内容之上。就像facebook的聊天记录。我不知道怎么做，将删除我的答案。tnx，我已经使用了你的库，但我有一个问题，我已经设置了一个按钮到头部视图，如果我想解释更多，我希望它将用户返回到我的应用程序：我在我的应用程序中有一个按钮，通过意图打开另一个应用程序，我希望通过单击头部按钮返回到我的应用程序，但当用户单击时，他返回到我应用程序中的新活动，我的MainActivity已再次创建，所有MainActivity布局元素都已重置，如何解决此问题？这不是上述问题的解决方案。。。这可能是一个工作周围。。。

package com.tpck.myapp;

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Toast;

public class HUD extends Service {
HUDView mView;

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

@Override
public void onCreate() {
super.onCreate();

Toast.makeText(getBaseContext(),"onCreate",    Toast.LENGTH_LONG).show();
mView = new HUDView(this);
WindowManager.LayoutParams params = new WindowManager.LayoutParams(

        WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY,
        WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
        PixelFormat.TRANSLUCENT);
        params.gravity = Gravity.RIGHT | Gravity.TOP;
        params.setTitle("Load Average");
 WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
wm.addView(mView, params);
}

@Override
public void onDestroy() {
super.onDestroy();
Toast.makeText(getBaseContext(),"onDestroy", Toast.LENGTH_LONG).show();
if(mView != null)
{
    ((WindowManager) getSystemService(WINDOW_SERVICE)).removeView(mView);
    mView = null;
}
    }
}

class HUDView extends ViewGroup {
private Paint mLoadPaint;

public HUDView(Context context) {
super(context);
Toast.makeText(getContext(),"HUDView", Toast.LENGTH_LONG).show();

mLoadPaint = new Paint();
mLoadPaint.setAntiAlias(true);
mLoadPaint.setTextSize(10);
mLoadPaint.setARGB(255, 255, 0, 0);
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawText("Hello World", 5, 15, mLoadPaint);
}

@Override
protected void onLayout(boolean arg0, int arg1, int arg2, int arg3,    int     arg4) {
}

@Override
public boolean onTouchEvent(MotionEvent event) {


Toast.makeText(getContext(),"onTouchEvent", Toast.LENGTH_LONG).show();
return true;
    }
}