Adnroid 类似iPhone的弹性ListView滚动

从2.3开始，android开始支持listview的overscroll, 应该很方便可以做出类似iPhone的弹性滚动，及越过list顶端或者底端，然后弹性滚回。大致如下：

package com.iaiai.activity;

import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.widget.ListView;

/**
 * 
 * <p>
 * Title: BounceListView.java
 * </p>
 * <p>

 * </p>
 * <p>
 * Http: iaiai.iteye.com
 * </p>
 * <p>
 * Create time: 2011-12-30 下午3:07:49
 * </p>
 * 
 * @author 丸子
 * @version 0.0.1
 */
public class BounceListView extends ListView {

  private static final int MAX_Y_OVERSCROLL_DISTANCE = 500;

  private Context mContext;
  private int mMaxYOverscrollDistance;

  public BounceListView(Context context) {
    super(context);
    mContext = context;
    initBounceListView();
  }

  public BounceListView(Context context, AttributeSet attrs) {
    super(context, attrs);
    mContext = context;
    initBounceListView();
  }

  public BounceListView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    mContext = context;
    initBounceListView();
  }

  private void initBounceListView() {
    // get the density of the screen and do some maths with it on the max
    // overscroll distance
    // variable so that you get similar behaviors no matter what the screen
    // size

    final DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();
    final float density = metrics.density;

    mMaxYOverscrollDistance = (int) (density * MAX_Y_OVERSCROLL_DISTANCE);
  }

  @Override
  protected boolean overScrollBy(int deltaX, int deltaY, int scrollX, int scrollY, int scrollRangeX,
      int scrollRangeY, int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) {
    // This is where the magic happens, we have replaced the incoming
    // maxOverScrollY with our own custom variable mMaxYOverscrollDistance;
    return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX, scrollRangeY, maxOverScrollX,
        mMaxYOverscrollDistance, isTouchEvent);
  }

}