Small case of Android phone floating window

//There is only one Button in the layoutpublic class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  (savedInstanceState);
  setContentView(.activity_main);
  findViewById().setOnClickListener(new () {
   @Override
   public void onClick(View view) {
   //The purpose is to start the Service to open the suspended form    startService(new Intent(, ));
    finish();
   }
  });

 }
}

/**
  * description: Open FloatView through Service
  * Author: ldm
  * Time: 20162016/8/17 14:03
  * Email: 1786911211@
  */
public class FloatService extends Service {
 @Override
 public void onCreate() {
  ();
  (this).showFloatViewOnWindow();
 }

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

/**
  * description:
  * Author: ldm
  * Time: 20162016/8/17 11:57
  * Email: 1786911211@
  */
public class CustomViewManager {
 //Context private Context mContext;
 //Example of this class private static CustomViewManager instance;
 //Custom FloatView private FloatView mFloatView;
 //Window Management private WindowManager mWindowManager;

 private CustomViewManager(Context context) {
   = context;
  mFloatView = new FloatView(mContext);
  mWindowManager = (WindowManager) (Context.WINDOW_SERVICE);
 }

 /**
   * @param
   * @description Get instance object through singleton mode
   * @author ldm
   * @time 2016/8/17 11:59
   */
 public static CustomViewManager getInstance(Context mContext) {
  if (null == instance) {
   synchronized () {
    if (null == instance) {
     instance = new CustomViewManager(mContext);
    }
   }
  }
  return instance;
 }

 /**
   * @param
   * @description Display custom FloatView on mobile screen
   * @author ldm
   * @time 2016/8/17 13:47
   */
 public void showFloatViewOnWindow() {
   parmas = new ();
   = ();
   = ();
  //The window pattern placement position   =  | ;
  // If the gravity property is ignored, it indicates the absolute X position of the window.   = 0;
  //If the gravity property is ignored, it indicates the absolute Y position of the window.   = 0;
  //// Phone window.  It is used for telephone interactions (especially incoming calls).  It is placed above all applications, under the status bar.   = .TYPE_SYSTEM_ALERT;
  //FLAG_NOT_FOCUSABLE prevents the window from gaining focus, so that the user can't send key events and button events to the window quickly.  //FLAG_NOT_TOUCH_MODAL Even if the window is available for focus, it still sends any event outside the window to other windows after the window.   = .FLAG_NOT_FOCUSABLE;
  // Desired bitmap format.  The default is opaque.  refer to.   = PixelFormat.RGBA_8888;
  (mFloatView, parmas);
 }
}

/**
  * description:
  * Author: ldm
  * Time: 20162016/8/17 11:17
  * Email: 1786911211@
  */
public class FloatView extends View {
 //The width of the floating ball private int floatWidth = 150;
 //The height of the floating ball private int floatHeight = 150;
 //Floating ball brush private Paint mPaint;
 //Draw a text brush private Paint mTextPaint;
 private String text = "50%";

 public FloatView(Context context) {
  super(context);
  initPaint();
 }


 public int getFloatWidth() {
  return floatWidth;
 }


 public int getFloatHeight() {
  return floatHeight;
 }

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

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

 /**
   * @param
   * @description Initialize the brush
   * @author ldm
   * @time 2016/8/17 11:37
   */
 private void initPaint() {
  //Set the floating ball brush  mPaint = new Paint();
  ();
  (true);
  (true);
  //Set text brush  mTextPaint = new Paint();
  (25);
  (true);
  ();
  (true);
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  //Set the size  setMeasuredDimension(floatWidth, floatHeight);
 }

 /**
   * @param
   * @description Draw the pattern
   * @author ldm
   * @time 2016/8/17 11:44
   */
 @Override
 protected void onDraw(Canvas canvas) {
  (canvas);
  //Draw the floating ball  (floatWidth / 2, floatHeight / 2, floatWidth / 2, mPaint);
  //Draw text   metrics = ();
  //Calculate the text size and refer to: ./3826268/871765/  float textWidth = (text);
  float x = floatWidth / 2 - textWidth / 2;
  float dy = -( + ) / 2;
  float y = floatHeight / 2 + dy;
  (text, x, y, mTextPaint);
 }
}

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

 <service android:name="." />