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Android列表视图(ListView)
ListView是一个显示滚动项列表的示视图组(viewgroup)，通过使用适配器(Adapter)把这些列表项自动插入到列表中。适配器比如从一个数组或是数据库查询获取到数据，然后转换每一项成为可放入到列表的视图。
列表的显示需要三个元素：
(1) ListView：用来展示列表的view。
(2) 适配器：用来把数据映射到ListView上。
(3) 数据：具体的将被映射的字符串、图片或是基本组件。
图1
对于我们如何使用适配器来动态插入view，参考链接：
1. 使用加载器(Using a Loader)
为了实现异步加载数据，且为了避免在查询时阻塞APP主线程，从Android3.0开始引入CursorLoader，这是一种查询Cursor的标准方式。当CursorLoader接收到Cursor结果(查询结束)，LoaderCallbacks接收到对onLoadFinished()方法的回调，此方法使用新的Cursor来更新适配器，然后列表视图显示这个结果。
虽然CursorLoader的API是从Android3.0(API 11)开始引入的，但可以通过使用支持的库来使用：及之后的版本。
public class ListViewLoader extends ListActivity implements LoaderManager.LoaderCallbacks<Cursor> { // This is the Adapter being used to display the list's data SimpleCursorAdapter mAdapter; // These are the Contacts rows that we will retrieve static final String[] PROJECTION = new String[] { ContactsContract.Data._ID, ContactsContract.Data.DISPLAY_NAME}; // This is the select criteria static final String SELECTION = "((" + ContactsContract.Data.DISPLAY_NAME + " NOTNULL)AND (" + ContactsContract.Data.DISPLAY_NAME + " != ''))"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Create a progress bar to display whilethe list loads ProgressBar progressBar = new ProgressBar(this); progressBar.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, Gravity.CENTER)); progressBar.setIndeterminate(true); getListView().setEmptyView(progressBar); // Must add the progress bar to the root ofthe layout ViewGroup root = (ViewGroup) findViewById(android.R.id.content); root.addView(progressBar); // For the cursor adapter, specify whichcolumns go into which views String[] fromColumns = { ContactsContract.Data.DISPLAY_NAME}; int[] toViews = { android.R.id.text1}; // The TextViewin simple_list_item_1 // Create an empty adapter we will use todisplay the loaded data. // We pass null for the cursor, then updateit in onLoadFinished() mAdapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_1, null, fromColumns, toViews, 0); setListAdapter(mAdapter); // Prepare the loader. Eitherre-connect with an existing one, // or start a new one. getLoaderManager().initLoader(0, null, this); } // Called when a new Loader needs to be created public Loader<Cursor> onCreateLoader(int id, Bundle args) { // Now create and return a CursorLoaderthat will take care of // creating a Cursor for the data beingdisplayed. return new CursorLoader(this, ContactsContract.Data.CONTENT_URI, PROJECTION, SELECTION, null, null); } // Called when a previously created loader has finished loading public void onLoadFinished(Loader<Cursor> loader, Cursor data) { // Swap the new cursor in. (Theframework will take care of closing the // old cursor once we return.) mAdapter.swapCursor(data); } // Called when a previously created loader is reset, making the dataunavailable public void onLoaderReset(Loader<Cursor> loader) { // This is called when the last Cursorprovided to onLoadFinished() // above is about to be closed. We needto make sure we are no // longer using it. mAdapter.swapCursor(null); } @Override public void onListItemClick(ListView l, View v, int position, long id) { // Do something when a list item is clicked } }
链接:
Android开发者：
Android之ListView原理学习与优化总结
Android的CursorLoader用法小结
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