建立搜索接口

Beginning in Android 3.0, using the SearchView widget as an item in the action bar is the preferred way to provide search in your app. Like with all items in the action bar, you can define the SearchView to show at all times, only when there is room, or as a collapsible action, which displays the SearchView as an icon initially, then takes up the entire action bar as a search field when the user clicks the icon.

Note: Later in this class, you will learn how to make your app compatible down to Android 2.1 (API level 7) for devices that do not support SearchView.

Add the Search View to the Action Bar

To add a SearchView widget to the action bar, create a file named res/menu/options_menu.xml in your project and add the following code to the file. This code defines how to create the search item, such as the icon to use and the title of the item. The collapseActionView attribute allows your SearchView to expand to take up the whole action bar and collapse back down into a normal action bar item when not in use. Because of the limited action bar space on handset devices, using the collapsibleActionView attribute is recommended to provide a better user experience.

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/search"
          android:title="@string/search_title"
          android:icon="@drawable/ic_search"
          android:showAsAction="collapseActionView|ifRoom"
          android:actionViewClass="android.widget.SearchView" />
</menu>

Note: If you already have an existing XML file for your menu items, you can add the <item> element to that file instead.

To display the SearchView in the action bar, inflate the XML menu resource (res/menu/options_menu.xml) in the onCreateOptionsMenu() method of your activity:

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.options_menu, menu);

    return true;
}

If you run your app now, the SearchView appears in your app's action bar, but it isn't functional. You now need to define how the SearchView behaves.

Create a Searchable Configuration

A searchable configuration defines how the SearchView behaves and is defined in a res/xml/searchable.xml file. At a minimum, a searchable configuration must contain an android:label attribute that has the same value as the android:label attribute of the <application> or <activity> element in your Android manifest. However, we also recommend adding an android:hint attribute to give the user an idea of what to enter into the search box:

<?xml version="1.0" encoding="utf-8"?>

<searchable xmlns:android="http://schemas.android.com/apk/res/android"
        android:label="@string/app_name"
        android:hint="@string/search_hint" />

In your application's manifest file, declare a <meta-data> element that points to the res/xml/searchable.xml file, so that your application knows where to find it. Declare the element in an <activity> that you want to display the SearchView in:

<activity ... >
    ...
    <meta-data android:name="android.app.searchable"
            android:resource="@xml/searchable" />

</activity>

In the onCreateOptionsMenu() method that you created before, associate the searchable configuration with the SearchView by calling setSearchableInfo(SearchableInfo):

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.options_menu, menu);

    // Associate searchable configuration with the SearchView
    SearchManager searchManager =
           (SearchManager) getSystemService(Context.SEARCH_SERVICE);
    SearchView searchView =
            (SearchView) menu.findItem(R.id.search).getActionView();
    searchView.setSearchableInfo(
            searchManager.getSearchableInfo(getComponentName()));

    return true;
}

The call to getSearchableInfo() obtains a SearchableInfo object that is created from the searchable configuration XML file. When the searchable configuration is correctly associated with your SearchView, the SearchView starts an activity with the ACTION_SEARCH intent when a user submits a query. You now need an activity that can filter for this intent and handle the search query.

Create a Searchable Activity

A SearchView tries to start an activity with the ACTION_SEARCH when a user submits a search query. A searchable activity filters for the ACTION_SEARCH intent and searches for the query in some sort of data set. To create a searchable activity, declare an activity of your choice to filter for the ACTION_SEARCH intent:

<activity android:name=".SearchResultsActivity" ... >
    ...
    <intent-filter>
        <action android:name="android.intent.action.SEARCH" />
    </intent-filter>
    ...
</activity>

In your searchable activity, handle the ACTION_SEARCH intent by checking for it in your onCreate() method.

Note: If your searchable activity launches in single top mode (android:launchMode="singleTop"), also handle the ACTION_SEARCH intent in the onNewIntent() method. In single top mode, only one instance of your activity is created and subsequent calls to start your activity do not create a new activity on the stack. This launch mode is useful so users can perform searches from the same activity without creating a new activity instance every time.

public class SearchResultsActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        ...
        handleIntent(getIntent());
    }

    @Override
    protected void onNewIntent(Intent intent) {
        ...
        handleIntent(intent);
    }

    private void handleIntent(Intent intent) {

        if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
            String query = intent.getStringExtra(SearchManager.QUERY);
            //use the query to search your data somehow
        }
    }
    ...
}

If you run your app now, the SearchView can accept the user's query and start your searchable activity with the ACTION_SEARCH intent. It is now up to you to figure out how to store and search your data given a query.