Android保存和恢复ListView的滑动后位置

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);
}
}

}

}