android弹性效果,android仿照ipone的弹性效果

package com.example.bounce;

import android.content.Context;

import android.util.AttributeSet;

import android.util.DisplayMetrics;

import android.widget.ListView;

public class BounceListView extends ListView{

private static final int MAX_Y_OVERSCROLL_DISTANCE = 200;

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);

}

}

package com.example.bounce;

import java.util.ArrayList;

import java.util.List;

import android.app.Activity;

import android.os.Bundle;

import android.widget.ArrayAdapter;

public class BounceListViewActivity extends Activity {

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_bounce_list_view);

BounceListView mBounceLv = (BounceListView)findViewById(R.id.list);

mBounceLv.setAdapter(new ArrayAdapter(this,android.R.layout.simple_list_item_1,getData()));

}

private List getData(){

List data = new ArrayList();

data.add("测试数据1");

data.add("测试数据2");

data.add("测试数据3");

data.add("测试数据4");

data.add("测试数据5");

data.add("测试数据6");

data.add("测试数据7");

data.add("测试数据8");

data.add("测试数据9");

data.add("测试数据10");

data.add("测试数据11");

data.add("测试数据12");

data.add("测试数据13");

return data;

}

}