使用AsyncTask 实现网络请求及PullToRefreshListView下拉刷新

[code]package com.example.helloworld;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListView;

import com.example.util.WebUtil;
import com.handmark.pulltorefresh.library.PullToRefreshBase;
import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener;
import com.handmark.pulltorefresh.library.PullToRefreshListView;

public class ThirdActivity extends Activity {

    private List<NewsItem> aList = new ArrayList<NewsItem>();
    private PullToRefreshListView mListView;
    private NewsAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_third);
        mListView = (PullToRefreshListView) findViewById(R.id.peopleListView);
        //异步消息处理封装类 AsyncTask
        new AsyncTask<Void, Void,List<NewsItem>>() {

            @Override
            protected List<NewsItem> doInBackground(Void... arg0) {
                WebUtil webUtil = new WebUtil();
                aList = webUtil.getNewsInfo();
                Log.i("ym", "准备..");
                webUtil.postNewsInfo();
                return aList;
            }
            protected void onPostExecute(java.util.List<NewsItem> result) {

                adapter = new NewsAdapter(ThirdActivity.this, aList);
                mListView.setAdapter(adapter);

            };

        }.execute();

        //PullToRefreshListView下拉刷新响应事件
        mListView.setOnRefreshListener(new OnRefreshListener<ListView>() {

            @Override
            public void onRefresh(PullToRefreshBase<ListView> refreshView) {

                new AsyncTask<Void, Void, Void>(){

                    @Override
                    protected Void doInBackground(Void... arg0) {
                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        return null;
                    }
                    protected void onPostExecute(Void result) {
                        NewsItem newsItem = new NewsItem("我是新标题", "我是新内容");
                        aList.add(0,newsItem);
                        adapter.notifyDataSetChanged();
                        mListView.onRefreshComplete();
                    };

                }.execute();
            }
        });

        /*//子线程访问网络,匿名类
        new Thread(new Runnable() {

            @Override
            public void run() {
                WebUtil webUtil = new WebUtil();
                result = webUtil.getNewsInfo();
                Log.i("hongye", result.get(1).getContent());
            }
        }).start();*/

    }
}