public class MainActivity extends AppCompatActivity {
  private ImageButton ibOk ;
  private int lastX;
  private int lastY;
  private int startLeft;
  private int startRight;
  private int startTop;
  private int startBottom;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ibOk = (ImageButton) findViewById(R.id.ib_ok);
    ibOk.setOnTouchListener(new View.OnTouchListener() {
      @Override
      public boolean onTouch(View v, MotionEvent event) {
        int action = event.getAction();
        //获取手机触摸的坐标
        int x = (int) event.getX();
        int y = (int) event.getY();
        switch (action) {
          case MotionEvent.ACTION_DOWN://按下,获取小球初始的位置
            startLeft = ibOk.getLeft();
            startRight = ibOk.getRight();
            startTop = ibOk.getTop();
            startBottom = ibOk.getBottom();
            lastX = x;
            lastY = y;
            break;
          case MotionEvent.ACTION_MOVE://移动,小球跟随手指的移动
            int offsetX = x - lastX;
            int offsetY = y - lastY;
            ibOk.layout(ibOk.getLeft() + offsetX, ibOk.getTop() + offsetY,
                ibOk.getRight() + offsetX, ibOk.getBottom() + offsetY);
            break;
          case MotionEvent.ACTION_UP://当手指抬起时,回到小球初始的位置
            ibOk.layout(startLeft, startTop, startRight, startBottom);
            break;
        }
        return true;

      }
    });
  }
  
}