Android保存和恢复ListView的滑动后位置

MainActivity如下:

package cc.testlistview;
import java.util.ArrayList;
import java.util.HashMap;
import cn.com.bravesoft.testlistviewloadmore.R;
import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;
import android.widget.SimpleAdapter;

/**
 * Demo描述: 
 * 保存和恢复ListView的当前位置
 * 
 * 注意事项:
 * onScrollStateChanged()方法中
 * v.getTop()方法的文档描述:
 * Top position of this view relative to its parent.
 * 
 * 测试方法:
 * 1 运行应用,滑动ListView
 * 2 ListView停止滑动后,按下back退出应用
 * 3 重新进入应用,ListView保持原位置
 */
public class MainActivity extends Activity {
	private int position;
	private int listViemItemTop;
	private ListView mListView;
	private SimpleAdapter mSimpleAdapter;
	private HashMap<String, Object> mHashMap;
	private ArrayList<HashMap<String, Object>> mArrayList;
	private final String LISTVIEW_PREFERENCES = "listview_preferences";

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		init();
	}

	private void init() {
		mListView = (ListView) findViewById(R.id.listView);
		mArrayList = new ArrayList<HashMap<String, Object>>();
		addDataForListView();
		mSimpleAdapter = new SimpleAdapter(
				MainActivity.this, 
				mArrayList,
				R.layout.listviewitem, 
				new String[] { "id" },
				new int[] { R.id.textView });
		mListView.setAdapter(mSimpleAdapter);
		mListView.setOnScrollListener(new OnScrollListenerImple());

	}

	private void addDataForListView() {
		for (int i = 0; i < 20; i++) {
			mHashMap = new HashMap<String, Object>();
			mHashMap.put("id", "" + i);
			mArrayList.add(mHashMap);
		}
	}

	@Override
	public void onPause() {
		super.onPause();
		SharedPreferences mySharedPreferences = 
		getSharedPreferences(LISTVIEW_PREFERENCES,Activity.MODE_PRIVATE);
		SharedPreferences.Editor edit = mySharedPreferences.edit();
		edit.putInt("listViemItemTop", listViemItemTop);
		edit.putInt("position", position);
		edit.commit();
	}

	@Override
	public void onResume() {
		super.onResume();
		SharedPreferences sharedPreferences = 
		getSharedPreferences(LISTVIEW_PREFERENCES,Activity.MODE_PRIVATE); 
		listViemItemTop = sharedPreferences.getInt("listViemItemTop", 0);
		position = sharedPreferences.getInt("position", 0);
		//reset ListView location
		mListView.setSelectionFromTop(position, listViemItemTop);
	}

	private class OnScrollListenerImple implements OnScrollListener {
		@Override
		public void onScroll(AbsListView listView, int firstVisibleItem,
				int visibleItemCount, int totalItemCount) {
			
		}
       
		@Override
		public void onScrollStateChanged(AbsListView listview, int scrollState) {
			if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
				position = mListView.getFirstVisiblePosition();
				View itemView = mListView.getChildAt(0);
				listViemItemTop = (itemView == null) ? 0 : itemView.getTop();
				System.out.println("---> listViemItemTop=" + listViemItemTop);
			}
		}

	}

}

main.xml如下:

<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

    <ListView
        android:id="@+id/listView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_centerInParent="true"
     />

</RelativeLayout>

listviewitem.xml如下:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <TextView
        android:id="@+id/textView"
        android:layout_width="fill_parent"
        android:gravity="center"
        android:layout_height="80dip"
     />

</RelativeLayout>