IT资讯----------上拉加载，下拉刷新和缓存
来源：互联网 发布：php strcmp 编辑：程序博客网 时间：2024/05/22 00:10
该App已经上传到百度应用市场：http://shouji.baidu.com/soft/item?docid=8928185&from=as&f=search_app_it%E8%B5%84%E8%AE%AF%40list_1_image%402%40header_all_input
有兴趣的可以下载看看。接下来我会公布源代码，不过该App并没有使用代码混淆，所以可以通过反编译清楚的看到源码。
首先是对MainFragment.java编写，真对XListView实现下拉刷新和上拉加载。
@Overridepublic void onLoadMore() { new LoadDatasTask().execute(LOAD_MORE);}@Overridepublic void onRefresh() { new LoadDatasTask().execute(LOAD_REFREASH);}
我们对下拉刷新和上拉加载调用了一个异步任务，传入了操作的标识符，下面具体看个类：
/** * 记载数据的异步任 * * @author */class LoadDatasTask extends AsyncTask<Integer, Void, Integer> { @Override protected Integer doInBackground(Integer... params) { switch (params[0]) { case LOAD_MORE: loadMoreData(); break; case LOAD_REFREASH: refreashData(); break; } return -1; } @Override protected void onPostExecute(Integer result) { switch (result) { case TIP_ERROR_NO_NETWORK: Toast.makeText(getActivity(), "没网络连接", Toast.LENGTH_SHORT).show(); mAdapter.notifyDataSetChanged(); mXlistView.stopRefresh(); break; case TIP_ERROR_SERVER: Toast.makeText(getActivity(), "服务器错误", Toast.LENGTH_SHORT).show(); break; default: break; } switch (select) { case 1: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes)); break; case 2: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_cto)); break; case 3: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_blog_house)); break; case 4: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_iteye)); break; } mXlistView.stopRefresh(); mXlistView.stopLoadMore(); }}
loadMoreData();和 refreashData();
先看loadMoreData:
/** * 根据网络决定是从哪里取数据 */public void loadMoreData() { System.out.println("isLoadingDataFromNetwork------" + isLoadingDataFromNetwork); if (isLoadingDataFromNetwork) { currentPage =currentPage+ 1; List<NewsItem> newsItems = null; try { switch (select) { case 1: newsItems = newsItemBiz.getNewsItems(newTypes, currentPage); break; case 2: newsItems = newItem51CTO.getNewsItems(newTypes_cto, currentPage); break; case 3: newsItems = blogHouse.getNewsItems(newTypes_blog_house, currentPage); break; case 4: newsItems = iTeye.getNewsItems(newTypes_iteye, currentPage,newTypes_iteye); break; } newsItemDao.add(newsItems,select); mAdapter.addAll(newsItems); } catch (Exception e) { e.printStackTrace(); } } else { // 从数据库加载的 currentPage += 1; List<NewsItem> newsItems = null; switch (select) { case 1: newsItems = newsItemDao.list(newTypes, currentPage,select); break; case 2: newsItems = newsItemDao.list(newTypes_cto, currentPage,select); break; case 3: newsItems = newsItemDao.list(newTypes_blog_house, currentPage,select); break; case 4: newsItems = newsItemDao.list(newTypes_iteye, currentPage,select); break; } if(newsItems!=null) { mAdapter.addAll(newsItems); } }}
可以看到，如果当前app上的数据是从网络更新的即最新数据，我们会继续去网络加载下一页的数据，并且使用mNewsItemDao.add方法，插入我们的app的数据库中，供没有网络时使用。如果当前数据是缓存数据，我们则继续去数据库加载。
接下来看refreashData方法：
首先检查网络连接情况，没有的话，则去数据库加载，并设置isLoadingDataFromNetWork=false，如果有的话从网络加载，并清空该类型新闻的数据，更新数据库缓存数据。
下面是完整MainFragment.java：
public class MainFragment extends Fragment implements IXListViewRefreshListener, IXListViewLoadMore { private static final int LOAD_MORE = 0x110; private static final int LOAD_REFREASH = 0x111; private static final int TIP_ERROR_NO_NETWORK = 0x112; private static final int TIP_ERROR_SERVER = 0x113; //是否是第一次进入 private boolean isFirstIn = true; //是否连接网络 private boolean isConnNet = false; //选择是选择哪个博客 1：CSDN 2：51CTO 3：博客园 4：ITEYE博客 private int select; //选择的是博客的哪个 private int selectType; /** * 当前数据是否从网络获取 */ private boolean isLoadingDataFromNetwork=true; //取CSDN数据 private int newTypes = Constant.NEW_TYPE_YEJIE; //取51CTO数据 private int newTypes_cto = Constant.NEWS_TYPE_NETWORK; //取博客园数据 private int newTypes_blog_house = Constant.NEWS_TYPE_HOME; //取ITeye数据 private int newTypes_iteye = Constant.NEWS_TYPE_NEW; private int currentPage = 1; //CSDN private NewsItemBiz newsItemBiz; //51CTO private NewItem51CTO newItem51CTO; //博客园 private NewItemBlogHouse blogHouse; //ITeye private NewItemITeye iTeye; private me.maxwin.view.XListView mXlistView; private NewsItemAdapter mAdapter; private List<NewsItem> mDatas = new ArrayList<NewsItem>(); /** * 与数据库交互 */ private NewsItemDao newsItemDao; public MainFragment() { } public MainFragment(int newsType, int select) { this.newTypes = newsType; this.newTypes_cto = newsType + 5; this.newTypes_blog_house = newsType + 9; this.newTypes_iteye = newsType + 13; this.select = select; newsItemBiz = new NewsItemBiz(); newItem51CTO = new NewItem51CTO(); blogHouse = new NewItemBlogHouse(); iTeye = new NewItemITeye(); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View view = inflater.inflate(R.layout.tab_item_fragment_main, container, false); return view; } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); newsItemDao = new NewsItemDao(getContext()); mAdapter = new NewsItemAdapter(getActivity(), mDatas, select); mAdapter.setSelectType(newTypes_iteye); mXlistView = (me.maxwin.view.XListView) getView().findViewById(R.id.id_xlistView); mXlistView.setAdapter(mAdapter); mXlistView.setPullRefreshEnable(this); mXlistView.setPullLoadEnable(this); switch (select) { case 1: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes)); break; case 2: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_cto)); break; case 3: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_blog_house)); break; case 4: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_iteye)); break; } // mXlistView.startRefresh(); mXlistView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { NewsItem newsItem = mDatas.get(position-1); NewsItem nextItem=mDatas.get(position); Intent intent=null; if (newTypes_iteye==17){ intent = new Intent(getActivity(), SubjectsActivity.class); intent.putExtra("url", newsItem.getLink()); }else { intent = new Intent(getActivity(), NewsContentActivity.class); intent.putExtra("url", newsItem.getLink()); intent.putExtra("nextUrl", nextItem.getLink()); intent.putExtra("select", select); intent.putExtra("cuttenrPage", currentPage); } startActivity(intent); } }); if (isFirstIn) { /** * 进来时直接刷新 */ mXlistView.startRefresh(); isFirstIn = false; } else { mXlistView.NotRefreshAtBegin(); } } @Override public void onLoadMore() { new LoadDatasTask().execute(LOAD_MORE); } @Override public void onRefresh() { new LoadDatasTask().execute(LOAD_REFREASH); } /** * 记载数据的异步任 * * @author */ class LoadDatasTask extends AsyncTask<Integer, Void, Integer> { @Override protected Integer doInBackground(Integer... params) { switch (params[0]) { case LOAD_MORE: loadMoreData(); break; case LOAD_REFREASH: refreashData(); break; } return -1; } @Override protected void onPostExecute(Integer result) { switch (result) { case TIP_ERROR_NO_NETWORK: Toast.makeText(getActivity(), "没网络连接", Toast.LENGTH_SHORT).show(); mAdapter.notifyDataSetChanged(); mXlistView.stopRefresh(); break; case TIP_ERROR_SERVER: Toast.makeText(getActivity(), "服务器错误", Toast.LENGTH_SHORT).show(); break; default: break; } switch (select) { case 1: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes)); break; case 2: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_cto)); break; case 3: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_blog_house)); break; case 4: mXlistView.setRefreshTime(AppUtil.getRefreashTime(getActivity(), newTypes_iteye)); break; } mXlistView.stopRefresh(); mXlistView.stopLoadMore(); } } /** * 刷新获取数据 * * @return */ public Integer refreashData() { if (NetUtil.checkNet(getActivity())) { isConnNet = true; List<NewsItem> newsItems = null; try { switch (select) { case 1: newsItems = newsItemBiz.getNewsItems(newTypes, currentPage); List<NewsItem> newsItem1 = new ArrayList<>(); for (int i = 0; i <= newsItems.size() / 2; i++) { newsItem1.add(newsItems.get(i)); } mAdapter.setDatas(newsItem1); mDatas=newsItem1; isLoadingDataFromNetwork = true; // 设置刷新时间 AppUtil.setRefreashTime(getActivity(), newTypes); // 清除数据库数据 newsItemDao.deleteAll(newTypes,select); // 存入数据库 newsItemDao.add(newsItems,select); break; case 2: newsItems = newItem51CTO.getNewsItems(newTypes_cto, currentPage); List<NewsItem> newsItem2 = new ArrayList<>(); for (int i = 0; i <= newsItems.size() / 2; i++) { newsItem2.add(newsItems.get(i)); } mAdapter.setDatas(newsItem2); mDatas=newsItem2; isLoadingDataFromNetwork = true; // 设置刷新时间 AppUtil.setRefreashTime(getActivity(), newTypes_cto); // 清除数据库数据 newsItemDao.deleteAll(newTypes_cto,select); // 存入数据库 newsItemDao.add(newsItem2,select); break; case 3: newsItems = blogHouse.getNewsItems(newTypes_blog_house, currentPage); List<NewsItem> newsItem3 = new ArrayList<>(); for (int i = 0; i <= newsItems.size() / 2; i++) { newsItem3.add(newsItems.get(i)); } mAdapter.setDatas(newsItem3); mDatas=newsItem3; isLoadingDataFromNetwork = true; // 设置刷新时间 AppUtil.setRefreashTime(getActivity(), newTypes_blog_house); // 清除数据库数据 newsItemDao.deleteAll(newTypes_blog_house,select); // 存入数据库 newsItemDao.add(newsItem3,select); break; case 4: newsItems = iTeye.getNewsItems(newTypes_iteye, currentPage, newTypes_iteye); List<NewsItem> newsItem4 = new ArrayList<>(); for (int i = 0; i <= newsItems.size() / 2; i++) { newsItem4.add(newsItems.get(i)); } mAdapter.setDatas(newsItem4); mDatas=newsItem4; isLoadingDataFromNetwork = true; // 设置刷新时间 AppUtil.setRefreashTime(getActivity(), newTypes_iteye); // 清除数据库数据 newsItemDao.deleteAll(newTypes_iteye,select); // 存入数据库 newsItemDao.add(newsItem4,select); break; } // mDatas = newsItems; } catch (Exception e) { e.printStackTrace(); isLoadingDataFromNetwork = false; return TIP_ERROR_SERVER; } } else { isConnNet = false; isLoadingDataFromNetwork = false; List<NewsItem> newsItems = null; switch (select) { case 1: //从数据库取数据 newsItems = newsItemDao.list(newTypes, currentPage,select); break; case 2: newsItems = newsItemDao.list(newTypes_cto, currentPage,select); break; case 3: newsItems = newsItemDao.list(newTypes_blog_house, currentPage,select); break; case 4: newsItems = newsItemDao.list(newTypes_iteye, currentPage,select); break; } mDatas = newsItems; return TIP_ERROR_NO_NETWORK; } return -1; } /** * 根据网络决定是从哪里取数据 */ public void loadMoreData() { System.out.println("isLoadingDataFromNetwork------" + isLoadingDataFromNetwork); if (isLoadingDataFromNetwork) { currentPage =currentPage+ 1; List<NewsItem> newsItems = null; try { switch (select) { case 1: newsItems = newsItemBiz.getNewsItems(newTypes, currentPage); break; case 2: newsItems = newItem51CTO.getNewsItems(newTypes_cto, currentPage); break; case 3: newsItems = blogHouse.getNewsItems(newTypes_blog_house, currentPage); break; case 4: newsItems = iTeye.getNewsItems(newTypes_iteye, currentPage,newTypes_iteye); break; } newsItemDao.add(newsItems,select); mAdapter.addAll(newsItems); } catch (Exception e) { e.printStackTrace(); } } else { // 从数据库加载的 currentPage += 1; List<NewsItem> newsItems = null; switch (select) { case 1: newsItems = newsItemDao.list(newTypes, currentPage,select); break; case 2: newsItems = newsItemDao.list(newTypes_cto, currentPage,select); break; case 3: newsItems = newsItemDao.list(newTypes_blog_house, currentPage,select); break; case 4: newsItems = newsItemDao.list(newTypes_iteye, currentPage,select); break; } if(newsItems!=null) { mAdapter.addAll(newsItems); } } } @Override public void onResume() { super.onResume(); MobclickAgent.onPageStart("MainFragment"); } @Override public void onPause() { super.onPause(); MobclickAgent.onPageEnd("MainFragment"); }}
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