android.widget.ImageView
方法：
(1)
public void setVisibility (int visibility) //visibility:能见度,可见性
Added in API level 1
Set the enabled state of this view. //激活的,可行的
VISIBLE:======>View类里面的一个常量:Constant Value: 0 (0x00000000)
Constant Value: 4 (0x00000004)Constant Value: 8 (0x00000008)
public static final int VISIBLE
Added in API level 1
This view is visible. Use with setVisibility(int) and android:visibility.
INVISIBLE:======>View类里面的一个常量:
public static final int INVISIBLE
Added in API level 1
This view is invisible, but it still takes up space for layout purposes. Use with setVisibility(int) and android:visibility.
GONE: ======>View类里面的一个常量:
public static final int GONE
Added in API level 1
This view is invisible, and it doesn't take any space for layout purposes. Use with setVisibility(int) and android:visibility.