imageView.setOnTouchListener(imgListener);

public void getActionBarHeight() {
    TypedValue tv = new TypedValue();
    if (getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true))
        actionBarHeight = TypedValue.complexToDimensionPixelSize(tv.data,getResources().getDisplayMetrics());
}

private View.OnTouchListener imgListener = new View.OnTouchListener() {
    private float lengthXFromLeftToTouchEvent, lengthYFromTopToTouchEvent;
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction()) {  
            case MotionEvent.ACTION_DOWN:
                //計算點下去的位置到圖片左上角位置的距離
                lengthXFromLeftToTouchEvent = event.getRawX() - imageView.getX();
                lengthYFromTopToTouchEvent = event.getRawY() - imageView.getY() - actionBarHeight;
                break;
                
            case MotionEvent.ACTION_MOVE:
                mx = (int) (event.getRawX() - lengthXFromLeftToTouchEvent);
                my = (int) (event.getRawY() - lengthYFromTopToTouchEvent - actionBarHeight);
                v.layout(mx, my, mx + v.getWidth(), my + v.getHeight());
                break;
                
            case MotionEvent.ACTION_UP:
                imageView.layout(mx, my, mx + imageView.getWidth(), my + imageView.getHeight());
                break;
        }
        return true;
    }
};

@Override
protected void onPause() {
    super.onPause();
    sharedpreferencesEditor.saveInt("lengthXFromLeftToTouchEvent", mx);
    sharedpreferencesEditor.saveInt("lengthYFromTopToTouchEvent", my);
}

public void initView() {
    imageView = findViewById(R.id.imageView);
    mx = sharedpreferencesEditor.readInt("lengthXFromLeftToTouchEvent");
    my = sharedpreferencesEditor.readInt("lengthYFromTopToTouchEvent");
    imageView.layout(mx, my, mx + imageView.getWidth(), my + imageView.getHeight());
}

v.layout(mx, my, mx + v.getWidth(), my + v.getHeight());

v.setX(mx);
v.setY(mx);