显示快速联系人徽章

本页介绍了如何向您的界面添加 QuickContactBadge 以及如何为其绑定数据。QuickContactBadge 是一个 widget，最初显示为缩略图。虽然您可以为缩略图使用任何 Bitmap，但通常会使用从联系人照片缩略图解码而来的 Bitmap。

小图片用作控件；当用户点按图片时，QuickContactBadge 会展开为一个对话框，其中包含以下内容

大图片
与联系人关联的大图片，如果图片不可用，则显示占位符图形。
应用图标
对于可由内置应用处理的每条详细信息，都有一个对应的应用图标。例如，如果联系人的详细信息包含一个或多个电子邮件地址，则会出现一个电子邮件图标。当用户点按该图标时，会显示该联系人的所有电子邮件地址。当用户点按其中一个地址时，电子邮件应用会显示一个屏幕，供用户撰写发送到所选电子邮件地址的消息。

QuickContactBadge 视图提供了即时访问联系人详细信息以及与联系人快速交流的方式。用户无需查找联系人、查找和复制信息，然后将其粘贴到相应的应用中。相反，他们可以点按 QuickContactBadge，选择他们想要使用的交流方式，然后直接将该方式的信息发送到相应的应用。

添加 QuickContactBadge 视图

要添加 QuickContactBadge，请在布局中插入一个 <QuickContactBadge> 元素，如下例所示

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent">
...
    <QuickContactBadge
               android:id=@+id/quickbadge
               android:layout_height="wrap_content"
               android:layout_width="wrap_content"
               android:scaleType="centerCrop"/>
    ...
</RelativeLayout>

检索提供程序数据

要在 QuickContactBadge 中显示联系人，您需要联系人的内容 URI 和小图片的 Bitmap。您可以从 Contacts Provider 中检索的列生成内容 URI 和 Bitmap。将这些列指定为您用于将数据加载到 Cursor 中的投影的一部分。

对于 Android 3.0（API 级别 11）及更高版本，请在您的投影中包含以下列

对于 Android 2.3.3（API 级别 10）及更低版本，请使用以下列

本页上的示例假定已加载包含这些列和任何其他选定列的 Cursor。要了解如何检索 Cursor 中的列，请参阅检索联系人列表。

设置联系人 URI 和缩略图

获得所需的列后，您可以将数据绑定到 QuickContactBadge。

设置联系人 URI

要为联系人设置内容 URI，请调用 getLookupUri(id,lookupKey) 以获取 CONTENT_LOOKUP_URI，然后调用 assignContactUri() 来设置联系人。如下例所示

Kotlin

    // The Cursor that contains contact rows
    var cursor: Cursor? = null
    // The index of the _ID column in the Cursor
    var idColumn: Int = 0
    // The index of the LOOKUP_KEY column in the Cursor
    var lookupKeyColumn: Int = 0
    // A content URI for the desired contact
    var contactUri: Uri? = null
    // A handle to the QuickContactBadge view
    ...
    cursor?.let { cursor ->
        /*
         * Insert code here to move to the desired cursor row
         */
        // Gets the _ID column index
        idColumn = cursor.getColumnIndex(ContactsContract.Contacts._ID)
        // Gets the LOOKUP_KEY index
        lookupKeyColumn = cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY)
        // Gets a content URI for the contact
        contactUri = ContactsContract.Contacts.getLookupUri(
                cursor.getLong(idColumn),
                cursor.getString(lookupKeyColumn)
        )
        binding.badge.assignContactUri(contactUri)
    }

Java

    // The Cursor that contains contact rows
    Cursor cursor;
    // The index of the _ID column in the Cursor
    int idColumn;
    // The index of the LOOKUP_KEY column in the Cursor
    int lookupKeyColumn;
    // A content URI for the desired contact
    Uri contactUri;
    ...
    /*
     * Insert code here to move to the desired cursor row
     */
    // Gets the _ID column index
    idColumn = cursor.getColumnIndex(ContactsContract.Contacts._ID);
    // Gets the LOOKUP_KEY index
    lookupKeyColumn = cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY);
    // Gets a content URI for the contact
    contactUri =
            Contacts.getLookupUri(
                cursor.getLong(idColumn),
                cursor.getString(lookupKeyColumn)
            );
    binding.badge.assignContactUri(contactUri);

当用户点按 QuickContactBadge 图标时，联系人的详细信息会出现在对话框中。

设置照片缩略图

为 QuickContactBadge 设置联系人 URI 不会自动加载联系人的缩略图照片。要加载照片，请从联系人的 Cursor 行获取照片的 URI，使用该 URI 打开包含压缩缩略图照片的文件，并将该文件读取到 Bitmap 中。

注意：PHOTO_THUMBNAIL_URI 列在 3.0 之前的平台版本中不可用。对于这些版本，您必须从 Contacts.Photo 子表中检索 URI。

首先，设置变量以访问包含 Contacts._ID 和 Contacts.LOOKUP_KEY 列的 Cursor

Kotlin

    // The column in which to find the thumbnail ID
    var thumbnailColumn: Int = 0
    /*
     * The thumbnail URI, expressed as a String.
     * Contacts Provider stores URIs as String values.
     */
    var thumbnailUri: String? = null
    ...
    cursor?.let { cursor ->
        /*
         * Gets the photo thumbnail column index if
         * platform version >= Honeycomb
         */
        thumbnailColumn = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            cursor.getColumnIndex(ContactsContract.Contacts.PHOTO_THUMBNAIL_URI)
            // Otherwise, sets the thumbnail column to the _ID column
        } else {
            idColumn
        }
        /*
         * Assuming the current Cursor position is the contact you want,
         * gets the thumbnail ID
         */
        thumbnailUri = cursor.getString(thumbnailColumn)
    }

Java

    // The column in which to find the thumbnail ID
    int thumbnailColumn;
    /*
     * The thumbnail URI, expressed as a String.
     * Contacts Provider stores URIs as String values.
     */
    String thumbnailUri;
    ...
    /*
     * Gets the photo thumbnail column index if
     * platform version >= Honeycomb
     */
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        thumbnailColumn =
                cursor.getColumnIndex(ContactsContract.Contacts.PHOTO_THUMBNAIL_URI);
    // Otherwise, sets the thumbnail column to the _ID column
    } else {
        thumbnailColumn = idColumn;
    }
    /*
     * Assuming the current Cursor position is the contact you want,
     * gets the thumbnail ID
     */
    thumbnailUri = cursor.getString(thumbnailColumn);
    ...

定义一个方法，该方法接受联系人的照片相关数据和目标视图的尺寸，并以 Bitmap 形式返回正确尺寸的缩略图。首先构建一个指向缩略图的 URI

Kotlin

    /**
     * Load a contact photo thumbnail and return it as a Bitmap,
     * resizing the image to the provided image dimensions as needed.
     * @param photoData photo ID Prior to Honeycomb, the contact's _ID value.
     * For Honeycomb and later, the value of PHOTO_THUMBNAIL_URI.
     * @return A thumbnail Bitmap, sized to the provided width and height.
     * Returns null if the thumbnail is not found.
     */
    private fun loadContactPhotoThumbnail(photoData: String): Bitmap? {
        // Creates an asset file descriptor for the thumbnail file
        var afd: AssetFileDescriptor? = null
        // try-catch block for file not found
        try {
            // Creates a holder for the URI
            val thumbUri: Uri = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                // If Android 3.0 or later,
                // sets the URI from the incoming PHOTO_THUMBNAIL_URI
                Uri.parse(photoData)
            } else {
                // Prior to Android 3.0, constructs a photo Uri using _ID
                /*
                 * Creates a contact URI from the Contacts content URI
                 * incoming photoData (_ID)
                 */
                val contactUri: Uri =
                        Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_URI, photoData)
                /*
                 * Creates a photo URI by appending the content URI of
                 * Contacts.Photo
                 */
                Uri.withAppendedPath(contactUri, ContactsContract.Contacts.Photo.CONTENT_DIRECTORY)
            }

            /*
             * Retrieves an AssetFileDescriptor object for the thumbnail URI
             * using ContentResolver.openAssetFileDescriptor
             */
            afd = activity?.contentResolver?.openAssetFileDescriptor(thumbUri, "r")
            /*
             * Gets a file descriptor from the asset file descriptor.
             * This object can be used across processes.
             */
            return afd?.fileDescriptor?.let {fileDescriptor ->
                // Decodes the photo file and returns the result as a Bitmap
                // if the file descriptor is valid
                BitmapFactory.decodeFileDescriptor(fileDescriptor, null, null)
            }
        } catch (e: FileNotFoundException) {
            /*
             * Handle file not found errors
             */
            null
        } finally {
            // In all cases, close the asset file descriptor
            try {
                afd?.close()
            } catch (e: IOException) {
            }
        }
    }

Java

    /**
     * Load a contact photo thumbnail and return it as a Bitmap,
     * resizing the image to the provided image dimensions as needed.
     * @param photoData photo ID Prior to Honeycomb, the contact's _ID value.
     * For Honeycomb and later, the value of PHOTO_THUMBNAIL_URI.
     * @return A thumbnail Bitmap, sized to the provided width and height.
     * Returns null if the thumbnail is not found.
     */
    private Bitmap loadContactPhotoThumbnail(String photoData) {
        // Creates an asset file descriptor for the thumbnail file
        AssetFileDescriptor afd = null;
        // try-catch block for file not found
        try {
            // Creates a holder for the URI
            Uri thumbUri;
            // If Android 3.0 or later
            if (Build.VERSION.SDK_INT
                    >=
                Build.VERSION_CODES.HONEYCOMB) {
                // Sets the URI from the incoming PHOTO_THUMBNAIL_URI
                thumbUri = Uri.parse(photoData);
            } else {
            // Prior to Android 3.0, constructs a photo Uri using _ID
                /*
                 * Creates a contact URI from the Contacts content URI
                 * incoming photoData (_ID)
                 */
                final Uri contactUri = Uri.withAppendedPath(
                        ContactsContract.Contacts.CONTENT_URI, photoData);
                /*
                 * Creates a photo URI by appending the content URI of
                 * Contacts.Photo
                 */
                thumbUri =
                        Uri.withAppendedPath(
                                contactUri, ContactsContract.Contacts.Photo.CONTENT_DIRECTORY);
            }

        /*
         * Retrieves an AssetFileDescriptor object for the thumbnail URI
         * using ContentResolver.openAssetFileDescriptor
         */
        afd = getActivity().getContentResolver().
                openAssetFileDescriptor(thumbUri, "r");
        /*
         * Gets a file descriptor from the asset file descriptor.
         * This object can be used across processes.
         */
        FileDescriptor fileDescriptor = afd.getFileDescriptor();
        // Decodes the photo file and returns the result as a Bitmap
        // if the file descriptor is valid
        if (fileDescriptor != null) {
            // Decodes the bitmap
            return BitmapFactory.decodeFileDescriptor(
                    fileDescriptor, null, null);
            }
        // If the file isn't found
        } catch (FileNotFoundException e) {
            /*
             * Handle file not found errors
             */
        // In all cases, close the asset file descriptor
        } finally {
            if (afd != null) {
                try {
                    afd.close();
                } catch (IOException e) {}
            }
        }
        return null;
    }

在代码中调用 loadContactPhotoThumbnail() 方法以获取缩略图 Bitmap，并使用结果在 QuickContactBadge 中设置照片缩略图

Kotlin

    ...
    /*
     * Decodes the thumbnail file to a Bitmap
     */
    mThumbnailUri?.also { thumbnailUri ->
        loadContactPhotoThumbnail(thumbnailUri).also { thumbnail ->
            /*
             * Sets the image in the QuickContactBadge.
             * QuickContactBadge inherits from ImageView.
             */
            badge.setImageBitmap(thumbnail)
        }
    }

Java

    ...
    /*
     * Decodes the thumbnail file to a Bitmap
     */
    Bitmap mThumbnail =
            loadContactPhotoThumbnail(thumbnailUri);
    /*
     * Sets the image in the QuickContactBadge.
     * QuickContactBadge inherits from ImageView.
     */
    badge.setImageBitmap(mThumbnail);

将 QuickContactBadge 添加到 ListView

QuickContactBadge 是显示联系人列表的 ListView 的一个有用补充。使用 QuickContactBadge 显示每个联系人的缩略图照片；当用户点按缩略图时，QuickContactBadge 对话框就会出现。

添加 QuickContactBadge 元素

首先，将 QuickContactBadge 视图元素添加到您的 item 布局中。例如，如果您想为您检索的每个联系人显示一个 QuickContactBadge 和一个姓名，请将以下 XML 放入布局文件中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">
    <QuickContactBadge
        android:id="@+id/quickcontact"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:scaleType="centerCrop"/>
    <TextView android:id="@+id/displayname"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_toRightOf="@+id/quickcontact"
              android:gravity="center_vertical"
              android:layout_alignParentRight="true"
              android:layout_alignParentTop="true"/>
</RelativeLayout>

在以下各部分中，此文件称为 contact_item_layout.xml。

设置自定义 CursorAdapter

要将 CursorAdapter 绑定到包含 QuickContactBadge 的 ListView，请定义一个扩展 CursorAdapter 的自定义 adapter。这种方法允许您在将 Cursor 中的数据绑定到 QuickContactBadge 之前对其进行处理。这种方法还允许您将多个 Cursor 列绑定到 QuickContactBadge。在常规 CursorAdapter 中，这些操作都无法实现。

您定义的 CursorAdapter 子类必须重写以下方法

CursorAdapter.newView()
膨胀新的 View 对象以容纳 item 布局。在该方法的重写中，存储布局的子 View 对象的句柄，包括子 QuickContactBadge。采用这种方法，您可以避免在每次膨胀新布局时都获取子 View 对象的句柄。

您必须重写此方法，以便能够获取各个子 View 对象的句柄。这项技术让您可以在 CursorAdapter.bindView() 中控制它们的绑定。

CursorAdapter.bindView()
将数据从当前的 Cursor 行移动到 item 布局的子 View 对象。您必须重写此方法，以便能够将联系人的 URI 和缩略图都绑定到 QuickContactBadge。默认实现只允许列和 View 之间存在一对一映射。

以下代码段包含 CursorAdapter 的自定义子类的示例

定义自定义列表 adapter

定义 CursorAdapter 的子类，包括其构造函数，并重写 newView() 和 bindView()

Kotlin

    /**
     * Defines a class that holds resource IDs of each item layout
     * row to prevent having to look them up each time data is
     * bound to a row
     */
    private data class ViewHolder(
            internal var displayname: TextView? = null,
            internal var quickcontact: QuickContactBadge? = null
    )

    /**
     *
     *
     */
    private inner class ContactsAdapter(
            context: Context,
            val inflater: LayoutInflater = LayoutInflater.from(context)
    ) : CursorAdapter(context, null, 0) {
        ...
        override fun newView(
                context: Context,
                cursor: Cursor,
                viewGroup: ViewGroup
        ): View {
            /* Inflates the item layout. Stores view references
             * in a ViewHolder class to prevent having to look
             * them up each time bindView() is called.
             */
            return ContactListLayoutBinding.inflate(inflater,
                    viewGroup,
                    false).also { binding ->
                view.tag = ViewHolder().apply {
                    displayname = binding.displayname
                    quickcontact = binding.quickcontact
                }
            }.root
        }
        ...
        override fun bindView(view: View?, context: Context?, cursor: Cursor?) {
            (view?.tag as? ViewHolder)?.also { holder ->
                cursor?.apply {
                    ...
                    // Sets the display name in the layout
                    holder.displayname?.text = getString(displayNameIndex)
                    ...
                    /*
                     * Generates a contact URI for the QuickContactBadge
                     */
                    ContactsContract.Contacts.getLookupUri(
                            getLong(idIndex),
                            cursor.getString(lookupKeyIndex)
                    ).also { contactUri ->
                        holder.quickcontact?.assignContactUri(contactUri)
                    }

                    getString(photoDataIndex)?.also {photoData ->
                        /*
                         * Decodes the thumbnail file to a Bitmap.
                         * The method loadContactPhotoThumbnail() is defined
                         * in the section "Set the contact URI and thumbnail."
                         */
                        loadContactPhotoThumbnail(photoData)?.also { thumbnailBitmap ->
                            /*
                             * Sets the image in the QuickContactBadge.
                             * QuickContactBadge inherits from ImageView.
                             */
                            holder.quickcontact?.setImageBitmap(thumbnailBitmap)
                        }
                    }
                }
            }

        }
    }

Java

    private class ContactsAdapter extends CursorAdapter {
        private LayoutInflater inflater;
        ...
        public ContactsAdapter(Context context) {
            super(context, null, 0);

            /*
             * Gets an inflater that can instantiate
             * the ListView layout from the file
             */
            inflater = LayoutInflater.from(context);
            ...
        }
        ...
        /**
         * Defines a class that holds resource IDs of each item layout
         * row to prevent having to look them up each time data is
         * bound to a row
         */
        private class ViewHolder {
            TextView displayname;
            QuickContactBadge quickcontact;
        }
        ...
        @Override
        public View newView(
                Context context,
                Cursor cursor,
                ViewGroup viewGroup) {
            /* Inflates the item layout. Stores view references
             * in a ViewHolder class to prevent having to look
             * them up each time bindView() is called.
             */
            final ContactListLayoutBinding binding =
            ContactListLayoutBinding.inflate(inflater, 
                viewGroup,
                false);
            final ViewHolder holder = new ViewHolder();
            holder.displayname =
                    binding.displayName;
            holder.quickcontact =
                    binding.quickContact;
            view.setTag(holder);
            return binding.root;
        }
        ...
        @Override
        public void bindView(
                View view,
                Context context,
                Cursor cursor) {
            final ViewHolder holder = (ViewHolder) view.getTag();
            final String photoData =
                    cursor.getString(photoDataIndex);
            final String displayName =
                    cursor.getString(displayNameIndex);
            ...
            // Sets the display name in the layout
            holder.displayname = cursor.getString(displayNameIndex);
            ...
            /*
             * Generates a contact URI for the QuickContactBadge
             */
            final Uri contactUri = Contacts.getLookupUri(
                    cursor.getLong(idIndex),
                    cursor.getString(lookupKeyIndex));
            holder.quickcontact.assignContactUri(contactUri);
            String photoData = cursor.getString(photoDataIndex);
            /*
             * Decodes the thumbnail file to a Bitmap.
             * The method loadContactPhotoThumbnail() is defined
             * in the section "Set the contact URI and thumbnail."
             */
            Bitmap thumbnailBitmap =
                    loadContactPhotoThumbnail(photoData);
            /*
             * Sets the image in the QuickContactBadge.
             * QuickContactBadge inherits from ImageView.
             */
            holder.quickcontact.setImageBitmap(thumbnailBitmap);
    }

设置变量

在您的代码中，设置变量，包括包含必需列的 Cursor 投影，如下例所示。

注意：以下代码段使用了 loadContactPhotoThumbnail() 方法，该方法定义在设置联系人 URI 和缩略图部分中。

Kotlin

/*
 * Defines a projection based on platform version. This ensures
 * that you retrieve the correct columns.
 */
private val PROJECTION: Array<out String> = arrayOf(
        ContactsContract.Contacts._ID,
        ContactsContract.Contacts.LOOKUP_KEY,
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            ContactsContract.Contacts.DISPLAY_NAME_PRIMARY
        } else {
            ContactsContract.Contacts.DISPLAY_NAME
        },
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            ContactsContract.Contacts.PHOTO_FILE_ID
        } else {
            /*
             * Although it's not necessary to include the
             * column twice, this keeps the number of
             * columns the same regardless of version
             */
            ContactsContract.Contacts._ID
        }
)
...
class ContactsFragment : Fragment(), LoaderManager.LoaderCallbacks<Cursor> {
    ...
    // Defines a ListView
    private val listView: ListView? = null
    // Defines a ContactsAdapter
    private val adapter: ContactsAdapter? = null
    ...
    // Defines a Cursor to contain the retrieved data
    private val cursor: Cursor? = null
    /*
     * As a shortcut, defines constants for the
     * column indexes in the Cursor. The index is
     * 0-based and always matches the column order
     * in the projection.
     */
    // Column index of the _ID column
    private val idIndex = 0
    // Column index of the LOOKUP_KEY column
    private val lookupKeyIndex = 1
    // Column index of the display name column
    private val displayNameIndex = 3
    /*
     * Column index of the photo data column.
     * It's PHOTO_THUMBNAIL_URI for Honeycomb and later,
     * and _ID for previous versions.
     */
    private val photoDataIndex: Int =
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) 3 else 0
    ...

Java

public class ContactsFragment extends Fragment implements
        LoaderManager.LoaderCallbacks<Cursor> {
...
    // Defines a ListView
    private ListView listView;
    // Defines a ContactsAdapter
    private ContactsAdapter adapter;
    ...
    // Defines a Cursor to contain the retrieved data
    private Cursor cursor;
    /*
     * Defines a projection based on platform version. This ensures
     * that you retrieve the correct columns.
     */
    private static final String[] PROJECTION =
            {
                ContactsContract.Contacts._ID,
                ContactsContract.Contacts.LOOKUP_KEY,
                (Build.VERSION.SDK_INT >=
                 Build.VERSION_CODES.HONEYCOMB) ?
                        ContactsContract.Contacts.DISPLAY_NAME_PRIMARY :
                        ContactsContract.Contacts.DISPLAY_NAME
                (Build.VERSION.SDK_INT >=
                 Build.VERSION_CODES.HONEYCOMB) ?
                        ContactsContract.Contacts.PHOTO_FILE_ID :
                        /*
                         * Although it's not necessary to include the
                         * column twice, this keeps the number of
                         * columns the same regardless of version
                         */
                        ContactsContract.Contacts._ID
            };
    /*
     * As a shortcut, defines constants for the
     * column indexes in the Cursor. The index is
     * 0-based and always matches the column order
     * in the projection.
     */
    // Column index of the _ID column
    private int idIndex = 0;
    // Column index of the LOOKUP_KEY column
    private int lookupKeyIndex = 1;
    // Column index of the display name column
    private int displayNameIndex = 3;
    /*
     * Column index of the photo data column.
     * It's PHOTO_THUMBNAIL_URI for Honeycomb and later,
     * and _ID for previous versions.
     */
    private int photoDataIndex =
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ?
            3 :
            0;
    ...

设置 ListView

在 Fragment.onCreate() 中，实例化自定义 cursor adapter 并获取 ListView 的句柄

Kotlin

    override fun onCreateView(
            inflater: LayoutInflater,
            container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {
        return FragmentListViewBinding.inflate(...).let { binding ->
            ...
            /*
             * Gets a handle to the ListView in the file
             * contact_list_layout.xml
             */
            listView = binding.contactList
            mAdapter?.also {
                listView?.adapter = it
            }
            ...
        }.root
    }
    ...

Java

    @Override
    public View onCreateView(LayoutInflater inflater,
            ViewGroup container, Bundle savedInstanceState) {
        FragmentListViewBinding binding = FragmentListViewBinding.inflate(...)
        ...
        /*
         * Gets a handle to the ListView in the file
         * contact_list_layout.xml
         */
        if (binding.contactListView != null && adapter != null) {
            binding.contactListView.setAdapter(adapter);
        }
        ...
    }
    ...

在 onViewCreated() 中，将 ContactsAdapter 绑定到 ListView

Kotlin

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    /*
     * Instantiates the subclass of
     * CursorAdapter
     */
    mAdapter = activity?.let {
        ContactsAdapter(it).also { adapter ->
            // Sets up the adapter for the ListView
            listView?.adapter = adapter
        }
    }
}

Java

@Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        ...
        /*
         * Instantiates the subclass of
         * CursorAdapter
         */
        mAdapter = new ContactsAdapter(getActivity());
        // Sets up the adapter for the ListView
        if (listView != null && mAdapter != null) {
            listView.setAdapter(mAdapter);
        }
        ...
    }
    ...

当您返回包含联系人数据的 Cursor 时（通常在 onLoadFinished() 中），调用 swapCursor() 将 Cursor 数据移动到 ListView。这会为联系人列表中的每个条目显示 QuickContactBadge。

Kotlin

override fun onLoadFinished(loader: Loader<Cursor>, cursor: Cursor) {
    // When the loader has completed, swap the cursor into the adapter
    mAdapter?.swapCursor(cursor)
}

Java

public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
        // When the loader has completed, swap the cursor into the adapter
        mAdapter.swapCursor(cursor);
    }

当您使用 CursorAdapter（或其子类）将 Cursor 绑定到 ListView，并且使用 CursorLoader 加载 Cursor 时，始终在 onLoaderReset() 的实现中清除对 Cursor 的引用。如下例所示

Kotlin

    override fun onLoaderReset(loader: Loader<Cursor>) {
        // Removes remaining reference to the previous Cursor
        adapter?.swapCursor(null)
    }

Java

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        // Removes remaining reference to the previous Cursor
        adapter.swapCursor(null);
    }