button.setOnTouchListener(new FloatingOnTouchListener());
 private class FloatingOnTouchListener implements View.OnTouchListener {
     private int lastX;
     private int lastY;
     @Override
     public boolean onTouch(View view, MotionEvent event) {
         switch (event.getAction()) {
             case MotionEvent.ACTION_DOWN:
                 isDrag = false;
                 lastX = (int) event.getRawX();
                 lastY = (int) event.getRawY();
                 break;
             case MotionEvent.ACTION_MOVE:
                 isDrag = true;
                 int nowX = (int) event.getRawX();
                 int nowY = (int) event.getRawY();
                 int movedX = nowX - lastX;
                 int movedY = nowY - lastY;
                 lastX = nowX;
                 lastY = nowY;
                 layoutParams.x = layoutParams.x + movedX;
                 layoutParams.y = layoutParams.y + movedY;
        //获取当前手指移动的x和y，通过updateViewLayout方法将改变后的x和y设置给button
                 mWindowManager.updateViewLayout(view, layoutParams);
                 break;
             case MotionEvent.ACTION_UP:
                 if (isDrag) {
                     log("lastX=" + lastX + "  screenWidth=" + screenWidth);
          //手指抬起时，判断是需要滑动到屏幕左边还是屏幕右边
                     if (lastX >= screenWidth / 2) {
                         setAnimation(view, lastX, screenWidth);
                     } else {
                         setAnimation(view, -lastX, 0);
                     }
                 }
                 break;
         }
    //返回true则消费事件，返回false则传递事件，此处特殊处理是为了和点击事件区分
         return isDrag || view.onTouchEvent(event);
     }

  public boolean onTouchEvent(MotionEvent ev) {
        final int action = ev.getAction();
        int x, y;
        if (action == MotionEvent.ACTION_DOWN) {
            mGestureAborted = false;
        }
        if (mGestureAborted) {
            return false;
        }
        switch (action) {
            case MotionEvent.ACTION_DOWN:
        //按下的时间
                mDownTime = SystemClock.uptimeMillis();
                setPressed(true);
                if (mCode != 0) {//按下事件
                    sendEvent(KeyEvent.ACTION_DOWN, 0, mDownTime);
                } else {
                    // Provide the same haptic feedback that the system offers for virtual keys.
                    performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);
                }
                removeCallbacks(mCheckLongPress);
                postDelayed(mCheckLongPress, ViewConfiguration.getLongPressTimeout());
                break;
            case MotionEvent.ACTION_MOVE:
                x = (int)ev.getX();
                y = (int)ev.getY();
                setPressed(x >= -mTouchSlop
                        && x < getWidth() + mTouchSlop
                        && y >= -mTouchSlop
                        && y < getHeight() + mTouchSlop);
                break;
            case MotionEvent.ACTION_CANCEL:
                setPressed(false);
                if (mCode != 0) {
                    sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);
                }
                removeCallbacks(mCheckLongPress);
                break;
            case MotionEvent.ACTION_UP:
                final boolean doIt = isPressed();
                setPressed(false);
                if (mCode != 0) {
                    if (doIt) {//抬起事件
                        sendEvent(KeyEvent.ACTION_UP, 0);
                        sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
                        playSoundEffect(SoundEffectConstants.CLICK);
                    } else {
                        sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);
                    }
                } else {
                    // no key code, just a regular ImageView
                    if (doIt) {
                        performClick();
                    }
                }
                removeCallbacks(mCheckLongPress);
                break;
        }
        return true;
    }
  //以下为我们给button添加的点击事件
    private void sendEvent(int action, int flags, long when) {
        int mCode = 4;
        Log.e(TAG, "mCode="+mCode + "  flags="+flags);
        final int repeatCount = (flags & KeyEvent.FLAG_LONG_PRESS) != 0 ? 1 : 0;
        final KeyEvent ev = new KeyEvent(when - 100, when, action, mCode, repeatCount,
                0, KeyCharacterMap.VIRTUAL_KEYBOARD, 0,
                flags | KeyEvent.FLAG_FROM_SYSTEM | KeyEvent.FLAG_VIRTUAL_HARD_KEY,
                InputDevice.SOURCE_KEYBOARD);
        InputManager.getInstance().injectInputEvent(ev,
                InputManager.INJECT_INPUT_EVENT_MODE_ASYNC);
    }
  button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.e(TAG,"click dragButton ...");
                final long mDownTime = SystemClock.uptimeMillis();
                //onBackPressed();
                sendEvent(KeyEvent.ACTION_DOWN, 0, mDownTime);
                new Handler().postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        sendEvent(KeyEvent.ACTION_UP, 0, SystemClock.uptimeMillis());
                    }
                }, 300);
            }
        });