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>
 * E-Mail: [e-mail]
 * </p>
 * <p>
 * QQ: 176291935
 * </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);
	}

}