android仿ios下拉框,android自定义ListView仿IOS阻尼效果

今天又在IOS上看到列表的"阻尼"效果&＃xff0c;就是列表拉到表头或者表尾时&＃xff0c;还可以继续往上或往下拉&＃xff0c;松开手后&＃xff0c;整个列表会弹回去&＃xff0c;来看效果图&＃xff1a;

整个实现重点在overScrollBy这个方法上&＃xff0c;当你滚动listview时会触发此事件&＃xff0c;它会根据表头或表尾的坐标&＃xff0c;及你所给的maxOverScrollY最大滚动纵坐标值来计算listview的表头或表尾的坐标。

默认的ListView的overScrollBy方法中maxOverScrollY&＃61;0&＃xff1b;所以你只能看到在表头或表尾有一条带颜色的线闪灯&＃xff0c;据说&＃xff0c;这是为了避免IOS的专利....

下面来看实现方式&＃xff1a;

activity_main.xml&＃xff1a;

android:id&＃61;"&＃64;&＃43;id/mylistview"

android:layout_width&＃61;"match_parent"

android:layout_height&＃61;"match_parent" >

MainActivity.java&＃xff1a;

public class MainActivity extends Activity {

private BaseListView listview;

&＃64;Override

protected void onCreate(Bundle savedInstanceState)

{

super.onCreate(savedInstanceState);

requestWindowFeature(Window.FEATURE_NO_TITLE);

setContentView(R.layout.activity_main);

listview &＃61; (BaseListView) findViewById(R.id.mylistview);

ArrayAdapter adapter &＃61; new ArrayAdapter(this, android.R.layout.simple_expandable_list_item_1, new String[] { "A", "A", "A", "A", "A", "A", "A", "A", "A"});

listview.setAdapter(adapter);

}

}      这个是重点

BaseListView.java

public class BaseListView extends ListView

{

private static final int MAX_Y_OVERSCROLL_DISTANCE &＃61; 200;

private Context mContext;

private int mMaxYOverscrollDistance;

public BaseListView(Context context)

{

super(context);

mContext &＃61; context;

initBounceListView();

}

public BaseListView(Context context, AttributeSet attrs)

{

super(context, attrs);

mContext &＃61; context;

initBounceListView();

}

public BaseListView(Context context, AttributeSet attrs, int defStyle)

{

super(context, attrs, defStyle);

mContext &＃61; context;

initBounceListView();

}

private void initBounceListView()

{

final DisplayMetrics metrics &＃61; mContext.getResources().getDisplayMetrics();

final float density &＃61; metrics.density;

mMaxYOverscrollDistance &＃61; (int) (density * MAX_Y_OVERSCROLL_DISTANCE);

}

&＃64;Override

protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX, int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent)

{

return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, maxOverScrollX, mMaxYOverscrollDistance, isTouchEvent);

}

}

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