xref: /frameworks/base/docs/html-intl/intl/ko/guide/components/loaders.jd

page.title=
parent.title=
parent.link=activities.html
@jd:body
<div id="qv-wrapper">
<div id="qv">
    <h2>  </h2>
    <ol>
    <li><a href="#summary"> API </a></li>
    <li><a href="#app">   </a>
      <ol>
        <li><a href="#requirements"></a></li>
        <li><a href="#starting"> </a></li>
        <li><a href="#restarting">  </a></li>
        <li><a href="#callback">LoaderManager  </a></li>
      </ol>
    </li>
    <li><a href="#example"></a>
       <ol>
         <li><a href="#more_examples"> </a></li>
        </ol>
    </li>
  </ol>

  <h2>Key </h2>
    <ol>
      <li>{@link android.app.LoaderManager}</li>
      <li>{@link android.content.Loader}</li>

    </ol>

    <h2> </h2>
   <ol>
     <li> <a href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/app/LoaderCursor.html">
LoaderCursor</a></li>
     <li> <a href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/app/LoaderThrottle.html">
LoaderThrottle</a></li>
   </ol>
  </div>
</div>

<p> Android 3.0  ,      
   .    .</p>
  <ul>
    <li> {@link android.app.Activity} {@link
android.app.Fragment}   .</li>
    <li>   .</li>
    <li>       
.</li>
    <li>    ,    
 .     
.</li>
  </ul>

<h2 id="summary"> API </h2>

<p>       
  .    .</p>

<table>
  <tr>
    <th>/</th>
    <th></th>
  </tr>
  <tr>
    <td>{@link android.app.LoaderManager}</td>
    <td>{@link android.app.Activity} 
{@link android.app.Fragment}   ,   {@link
android.content.Loader}    .  
{@link android.app.Activity}
  {@link android.app.Fragment}           .    
{@link android.content.CursorLoader}   ,
           .
    <br />
    <br />
       {@link android.app.LoaderManager}  .  {@link android.app.LoaderManager}    
.</td>
  </tr>
  <tr>
    <td>{@link android.app.LoaderManager.LoaderCallbacks}</td>
    <td>  {@link
android.app.LoaderManager}     .   {@link
android.app.LoaderManager.LoaderCallbacks#onCreateLoader onCreateLoader()}
       .</td>
  </tr>
  <tr>
    <td>{@link android.content.Loader}</td>
    <td>     .   
.  {@link
android.content.CursorLoader}  ,     .    
       
  . </td>
  </tr>
  <tr>
    <td>{@link android.content.AsyncTaskLoader}</td>
    <td>  {@link android.os.AsyncTask}   .</td>
  </tr>
  <tr>
    <td>{@link android.content.CursorLoader}</td>
    <td>{@link android.content.AsyncTaskLoader}  , 
{@link android.content.ContentResolver}  {@link
android.database.Cursor} .        {@link
android.content.Loader}  ,
{@link android.content.AsyncTaskLoader} 
      UI  .
      API      {@link
android.content.ContentProvider}
    .</td>
  </tr>
</table>

<p>         
   .  
      ,    {@link
android.app.LoaderManager}   {@link
android.content.CursorLoader}  {@link android.content.Loader}
  .       
    .</p>

<h2 id ="app">   </h2>
<p>  Android      . 
     .</p>
<ul>
  <li>{@link android.app.Activity}  {@link android.app.Fragment}.</li>
  <li>{@link android.app.LoaderManager} .</li>
  <li>{@link
android.content.ContentProvider}    {@link android.content.CursorLoader}. ,  
{@link android.content.Loader}  {@link android.content.AsyncTaskLoader}   
    .</li>
  <li>{@link android.app.LoaderManager.LoaderCallbacks} .
       
.</li>
<li>   (: {@link
android.widget.SimpleCursorAdapter})</li>
  <li>{@link android.content.ContentProvider}   ,
{@link android.content.CursorLoader}   .</li>
</ul>
<h3 id="starting"> </h3>

<p>{@link android.app.LoaderManager} {@link android.app.Activity} 
{@link android.app.Fragment}    {@link
android.content.Loader}  .    {@link
android.app.LoaderManager}  .</p>

<p>
 {@link
android.app.Activity#onCreate onCreate()}  ,  
{@link android.app.Fragment#onActivityCreated onActivityCreated()}   {@link android.content.Loader} .  
   .</p>

<pre>// Prepare the loader.  Either re-connect with an existing one,
// or start a new one.
getLoaderManager().initLoader(0, null, this);</pre>

<p>{@link android.app.LoaderManager#initLoader initLoader()} 
   .</p>
<ul>
  <li>   ID.   ID 0.</li>
<li>     
(  <code>null</code>).</li>

<li>{@link android.app.LoaderManager.LoaderCallbacks} .    
{@link android.app.LoaderManager}  .  
   {@link
android.app.LoaderManager.LoaderCallbacks}     
{@code this} .</li>
</ul>
<p>{@link android.app.LoaderManager#initLoader initLoader()}     
 .        .</p>
<ul>
  <li>ID     ,   
.</li>
  <li>ID    <em></em> ,
{@link android.app.LoaderManager#initLoader initLoader()}
{@link android.app.LoaderManager.LoaderCallbacks}  {@link android.app.LoaderManager.LoaderCallbacks#onCreateLoader onCreateLoader()} .
      .
  <a href="#onCreateLoader">onCreateLoader</a>  .</li>
</ul>
<p>   {@link android.app.LoaderManager.LoaderCallbacks}
    ,   
 .      
        
  ,   {@link
android.app.LoaderManager.LoaderCallbacks#onLoadFinished onLoadFinished()}
({@link android.app.LoaderManager#initLoader initLoader()} ).
      .      <a href="#onLoadFinished">
onLoadFinished</a> .</p>

<p>{@link android.app.LoaderManager#initLoader initLoader()}
  {@link android.content.Loader} ,       
. {@link android.app.LoaderManager}  
 . {@link android.app.LoaderManager}
    ,     
.    ,  
    (,          
<a href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/app/LoaderThrottle.html"> LoaderThrottle</a>   ).
    {@link
android.app.LoaderManager.LoaderCallbacks},      
   .      <a href="#callback">LoaderManager  </a> .</p>

<h3 id="restarting">  </h3>

<p>    {@link android.app.LoaderManager#initLoader initLoader()}  ,
  ID      .
,  .         
.</p>

<p>   {@link
android.app.LoaderManager#restartLoader restartLoader()} .  , 
{@link android.widget.SearchView.OnQueryTextListener} 
     .       
    .</p>

<pre>
public boolean onQueryTextChanged(String newText) {
    // Called when the action bar search text has changed.  Update
    // the search filter, and restart the loader to do a new query
    // with this filter.
    mCurFilter = !TextUtils.isEmpty(newText) ? newText : null;
    getLoaderManager().restartLoader(0, null, this);
    return true;
}</pre>

<h3 id="callback">LoaderManager  </h3>

<p>{@link android.app.LoaderManager.LoaderCallbacks} 
{@link android.app.LoaderManager}       . </p>
<p>,  {@link android.content.CursorLoader}  
    .   
   @link android.app.Activity#onStop
onStop()}  {@link android.app.Activity#onStart onStart()}     ,
       
 .       {@link android.app.LoaderManager.LoaderCallbacks}
 .       
       .</p>

<p>{@link android.app.LoaderManager.LoaderCallbacks}   
.</p>
<ul>
  <li>{@link android.app.LoaderManager.LoaderCallbacks#onCreateLoader onCreateLoader()} -
 ID    {@link android.content.Loader} .
</li></ul>
<ul>
  <li> {@link android.app.LoaderManager.LoaderCallbacks#onLoadFinished onLoadFinished()}
-      .
</li></ul>
<ul>
  <li>{@link android.app.LoaderManager.LoaderCallbacks#onLoaderReset onLoaderReset()}
-           
.
</li>
</ul>
<p>       .</p>

<h4 id ="onCreateLoader">onCreateLoader</h4>

<p>   (  {@link
android.app.LoaderManager#initLoader initLoader()} ),   ID   
 .   , {@link
android.app.LoaderManager.LoaderCallbacks}  {@link
android.app.LoaderManager.LoaderCallbacks#onCreateLoader onCreateLoader()} . 
  .   {@link
android.content.CursorLoader},   {@link
android.content.Loader}    . </p>

<p> , {@link
android.app.LoaderManager.LoaderCallbacks#onCreateLoader onCreateLoader()}
   {@link android.content.CursorLoader} .
{@link android.content.CursorLoader}      . 
{@link
android.content.ContentProvider}         .     .</p>
<ul>
  <li><em>uri</em>    URI. </li>
  <li><em></em>    .
<code>null</code>    ,  . </li>
  <li><em></em>     ,
SQL WHERE   (WHERE  ).
<code>null</code>   URI    . </li>
  <li><em>selectionArgs</em>   ?  .  
 <em>selectionArgs</em>   ,   
 .   . </li>
  <li><em>sortOrder</em>  SQL ORDER BY   
   (ORDER BY  ). <code>null</code>
    ,   .</li>
</ul>
<p>:</p>
<pre>
 // If non-null, this is the current filter the user has provided.
String mCurFilter;
...
public Loader&lt;Cursor&gt; 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;
  if (mCurFilter != null) {
    baseUri = Uri.withAppendedPath(Contacts.CONTENT_FILTER_URI,
          Uri.encode(mCurFilter));
  } else {
    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 = &quot;((&quot; + Contacts.DISPLAY_NAME + &quot; NOTNULL) AND (&quot;
      + Contacts.HAS_PHONE_NUMBER + &quot;=1) AND (&quot;
      + Contacts.DISPLAY_NAME + &quot; != '' ))&quot;;
  return new CursorLoader(getActivity(), baseUri,
      CONTACTS_SUMMARY_PROJECTION, select, null,
      Contacts.DISPLAY_NAME + &quot; COLLATE LOCALIZED ASC&quot;);
}</pre>
<h4 id="onLoadFinished">onLoadFinished</h4>

<p>       .
        
  .     
    (  ),      .  
 ,     .</p>


<p>            
 .     {@link
android.content.CursorLoader}  ,   {@link
android.database.Cursor#close close()}   . 
{@link android.widget.CursorAdapter}  , {@link
android.widget.SimpleCursorAdapter#swapCursor swapCursor()}   . 
 {@link android.database.Cursor}  . :</p>

<pre>
// This is the Adapter being used to display the list's data.<br
/>SimpleCursorAdapter mAdapter;
...

public void onLoadFinished(Loader&lt;Cursor&gt; loader, Cursor data) {
    // Swap the new cursor in. (The framework will take care of closing the
    // old cursor once we return.)
    mAdapter.swapCursor(data);
}</pre>

<h4 id="onLoaderReset">onLoaderReset</h4>

<p>            
.         
      . </p>
<p> 
{@link android.widget.SimpleCursorAdapter#swapCursor swapCursor()} ,
  <code>null</code> .</p>

<pre>
// This is the Adapter being used to display the list's data.
SimpleCursorAdapter mAdapter;
...

public void onLoaderReset(Loader&lt;Cursor&gt; 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);
}</pre>


<h2 id="example"></h2>

<p>    {@link android.widget.ListView}  {@link
android.app.Fragment}   . 
       .  {@link
android.content.CursorLoader}     .</p>

<p>        
 
{@link android.Manifest.permission#READ_CONTACTS READ_CONTACTS}    .</p>

<pre>
public static class CursorLoaderListFragment extends ListFragment
    implements OnQueryTextListener, LoaderManager.LoaderCallbacks&lt;Cursor&gt; {

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

  // If non-null, this is the current filter the user has provided.
  String mCurFilter;

  @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(&quot;No phone numbers&quot;);

    // We have a menu item to show in action bar.
    setHasOptionsMenu(true);

    // Create an empty adapter we will use to display the loaded data.
    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);

    // Prepare the loader. Either re-connect with an existing one,
    // or start a new one.
    getLoaderManager().initLoader(0, null, this);
  }

  @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    // Place an action bar item for searching.
    MenuItem item = menu.add(&quot;Search&quot;);
    item.setIcon(android.R.drawable.ic_menu_search);
    item.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
    SearchView sv = new SearchView(getActivity());
    sv.setOnQueryTextListener(this);
    item.setActionView(sv);
  }

  public boolean onQueryTextChange(String newText) {
    // Called when the action bar search text has changed. Update
    // the search filter, and restart the loader to do a new query
    // with this filter.
    mCurFilter = !TextUtils.isEmpty(newText) ? newText : null;
    getLoaderManager().restartLoader(0, null, this);
    return true;
  }

  @Override public boolean onQueryTextSubmit(String query) {
    // Don't care about this.
    return true;
  }

  @Override public void onListItemClick(ListView l, View v, int position, long id) {
    // Insert desired behavior here.
    Log.i(&quot;FragmentComplexList&quot;, &quot;Item clicked: &quot; + id);
  }

  // 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.CONTACT_PRESENCE,
    Contacts.PHOTO_ID,
    Contacts.LOOKUP_KEY,
  };
  public Loader&lt;Cursor&gt; 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;
    if (mCurFilter != null) {
      baseUri = Uri.withAppendedPath(Contacts.CONTENT_FILTER_URI,
          Uri.encode(mCurFilter));
    } else {
      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 = &quot;((&quot; + Contacts.DISPLAY_NAME + &quot; NOTNULL) AND (&quot;
        + Contacts.HAS_PHONE_NUMBER + &quot;=1) AND (&quot;
        + Contacts.DISPLAY_NAME + &quot; != '' ))&quot;;
    return new CursorLoader(getActivity(), baseUri,
        CONTACTS_SUMMARY_PROJECTION, select, null,
        Contacts.DISPLAY_NAME + &quot; COLLATE LOCALIZED ASC&quot;);
  }

  public void onLoadFinished(Loader&lt;Cursor&gt; loader, Cursor data) {
    // Swap the new cursor in. (The framework will take care of closing the
    // old cursor once we return.)
    mAdapter.swapCursor(data);
  }

  public void onLoaderReset(Loader&lt;Cursor&gt; 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);
  }
}</pre>
<h3 id="more_examples"> </h3>

<p>        <strong>ApiDemos</strong>
 .</p>
<ul>
  <li><a href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/app/LoaderCursor.html">
LoaderCursor</a>      
.</li>
  <li><a href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/app/LoaderThrottle.html"> LoaderThrottle</a>      
          .</li>
</ul>

<p>SDK       <a href="http://developer.android.com/resources/samples/get.html">
</a> . </p>