参考APIDEMO：sdk\samples\android-19\content\LoaderCursor

1、创建主布局文件，里面只包含一个Fragment。

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:id="@+id/FrameLayout1"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context=".MainActivity" >

    <fragment

        android:id="@+id/fragment_list"

        android:name="com.example.android.content.loadercursor.CursorLoaderListFragment"

        android:layout_width="match_parent"

        android:layout_height="match_parent" />

</FrameLayout>

2、创建主Activity文件中的android:name加载相应的Fragment

package com.example.android.content.loadercursor;

import android.app.Activity;

import android.app.ListFragment;

import android.app.LoaderManager;

import android.database.Cursor;

import android.os.Bundle;

import android.widget.SearchView;

/**

 * The entry point to the CursorLoader sample. This sample demonstrates the use

 * of the {@link LoaderManager} to retrieve data from a {@link Cursor}. Here, a

 * list of contacts is displayed in a {@link ListFragment} and filtered using a

 * {@link SearchView} ActionBar item.

 */

public class MainActivity extends Activity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

    }

}

3、创建相应的Fragment

package com.example.android.content.loadercursor;

import android.app.ListFragment;

import android.app.LoaderManager;

import android.content.CursorLoader;

import android.content.Loader;

import android.database.Cursor;

import android.net.Uri;

import android.os.Bundle;

import android.provider.ContactsContract.Contacts;

import android.view.View;

import android.widget.ListView;

import android.widget.SearchView;

import android.widget.SimpleCursorAdapter;

import android.widget.Toast;

/**

 * A {@link ListFragment} that shows the use of a {@link LoaderManager} to

 * display a list of contacts accessed through a {@link Cursor}.

 */

/*

 * (1)继承Fragment或者其子类，用于创建一个Fragment。实现LoaderManager.LoaderCallbacks接口，用于与Loader的交互

 * 。 官方文档： A callback interface for a client to interact with the LoaderManager.

 * For example, you use the onCreateLoader() callback method to create a new

 * loader.

 */

public class CursorLoaderListFragment extends ListFragment implements

		LoaderManager.LoaderCallbacks<Cursor> {

	// This is the Adapter being used to display the list's data.

	SimpleCursorAdapter mAdapter;

	// The SearchView for doing filtering.

	SearchView mSearchView;

	/*

	 * （2）在Activity被创建时调用此方法。Called when the fragment's activity has been

	 * created and this fragment's view hierarchy instantiated. You typically

	 * initialize a Loader within the activity's onCreate() method, or within

	 * the fragment's onActivityCreated() method.

	 */@Override

	public void onActivityCreated(Bundle savedInstanceState) {

		super.onActivityCreated(savedInstanceState);

		// Give some text to display if there is no data. In a real

		// application this would come from a resource.

		setEmptyText("No phone numbers");

		/*

		 * Create an empty adapter we will use to display the loaded data. The

		 * simple_list_item_2 layout contains two rows on top of each other

		 * (text1 and text2) that will show the contact's name and status.

		 */

		// （3）设置Fragment的顯示內容

		mAdapter = new SimpleCursorAdapter(getActivity(),

				android.R.layout.simple_list_item_2, null, new String[] {

						Contacts.DISPLAY_NAME, Contacts.CONTACT_STATUS },

				new int[] { android.R.id.text1, android.R.id.text2 }, 0);

		setListAdapter(mAdapter);

		// Start out with a progress indicator.

		setListShown(false);

		// Prepare the loader. Either re-connect with an existing one,

		// or start a new one.

		/*

		 * (4)創建一個Loader，此Loader用于為Fragment載入內容。You typically initialize a

		 * Loader within the activity's onCreate() method, or within the

		 * fragment's onActivityCreated() method.

		 * 此方法將自動調用LoaderManager.LoaderCallbacks接口的onCreateLoader方法。

		 */

		getLoaderManager().initLoader(0, null, this);

	}

	/**

	 * An item has been clicked in the {@link ListView}. Display a toast with

	 * the tapped item's id.

	 */

	@Override

	public void onListItemClick(ListView l, View v, int position, long id) {

		Toast.makeText(getActivity(), "Item clicked: " + id, Toast.LENGTH_LONG)

				.show();

	}

	// These are the Contacts rows that we will retrieve.

	static final String[] CONTACTS_SUMMARY_PROJECTION = new String[] {

			Contacts._ID, Contacts.DISPLAY_NAME, Contacts.CONTACT_STATUS,

			Contacts.LOOKUP_KEY, };

	/*

	 * （5）Loader被創建時的操作，一般用于加載內容。In this example, the onCreateLoader() callback

	 * method creates a CursorLoader. You must build the CursorLoader using its

	 * constructor method, which requires the complete set of information needed

	 * to perform a query to the ContentProvider.

	 */public Loader<Cursor> onCreateLoader(int id, Bundle args) {

		// This is called when a new Loader needs to be created. This

		// sample only has one Loader, so we don't care about the ID.

		// First, pick the base URI to use depending on whether we are

		// currently filtering.

		Uri baseUri;

		baseUri = Contacts.CONTENT_URI;

		// Now create and return a CursorLoader that will take care of

		// creating a Cursor for the data being displayed.

		String select = "((" + Contacts.DISPLAY_NAME + " NOTNULL) AND ("

				+ Contacts.HAS_PHONE_NUMBER + "=1) AND ("

				+ Contacts.DISPLAY_NAME + " != '' ))";

		String order = Contacts.DISPLAY_NAME + " COLLATE LOCALIZED ASC";

		return new CursorLoader(getActivity(), baseUri,

				CONTACTS_SUMMARY_PROJECTION, select, null, order);

	}

	/*

	 * （6）内容被加载完成后的操作。The loader will release the data once it knows the

	 * application is no longer using it. For example, if the data is a cursor

	 * from a CursorLoader, you should not call close() on it yourself. If the

	 * cursor is being placed in a CursorAdapter, you should use the

	 * swapCursor() method so that the old Cursor is not closed.

	 */public void onLoadFinished(Loader<Cursor> loader, Cursor data) {

		// Swap the new cursor in. (The framework will take care of closing the

		// old cursor once we return.)

		// Swap in a new Cursor, returning the old Cursor. Unlike

		// changeCursor(Cursor), the returned old Cursor is not closed.

		mAdapter.swapCursor(data);

		// The list should now be shown.

		if (isResumed()) {

			setListShown(true);

		} else {

			setListShownNoAnimation(true);

		}

	}

	// (7)Loader被重新加载时的操作。

	public void onLoaderReset(Loader<Cursor> loader) {

		// This is called when the last Cursor provided to onLoadFinished()

		// above is about to be closed. We need to make sure we are no

		// longer using it.

		mAdapter.swapCursor(null);

	}

}