編寫:[huanglizhuo](https://github.com/huanglizhuo) - 原文:[http://developer.android.com/training/tv/playback/card.html](http://developer.android.com/training/tv/playback/card.html) 在前面的課程中，我們創建一個目錄瀏覽器，實現了瀏覽 fragment，顯示了媒體項目的列表。在本課程中，我們將創建該卡視圖的媒體項目，并在瀏覽fragment中呈現出來。 [BaseCardView](http://developer.android.com/reference/android/support/v17/leanback/widget/BaseCardView.html)類以及子類顯示與媒體項目相關聯的元數據。在本節課程中使用的[ImageCardView](http://developer.android.com/reference/android/support/v17/leanback/widget/ImageCardView.html)類顯示隨著媒體項目的標題內容的圖像。 這節課介紹了GitHub上 [ Android Leanback sample app](https://github.com/googlesamples/androidtv-Leanback)的示例應用程序代碼。使用該示例代碼，開始你自己的應用程序。  ### 創建一個卡片呈現者 [Presenter](http://developer.android.com/reference/android/support/v17/leanback/widget/Presenter.html)生成視圖并把類和它們綁定起來。在你的瀏覽 fragment 中將內容呈現給用戶,你為內容卡片創建[Presenter](http://developer.android.com/reference/android/support/v17/leanback/widget/Presenter.html)并把它傳給適配器然后將內容呈現在屏幕上。在下面的代碼中,CardPresenter在[ LoaderManager](http://developer.android.com/reference/android/support/v4/app/LoaderManager.html)的[onLoadFinished](http://developer.android.com/reference/android/support/v4/app/LoaderManager.LoaderCallbacks.html#onLoadFinished(android.support.v4.content.Loader<D>, D))方法中被創建。 ~~~ @Override public void onLoadFinished(Loader<HashMap<String, List<Movie>>> arg0, HashMap<String, List<Movie>> data) { mRowsAdapter = new ArrayObjectAdapter(new ListRowPresenter()); CardPresenter cardPresenter = new CardPresenter(); int i = 0; for (Map.Entry<String, List<Movie>> entry : data.entrySet()) { ArrayObjectAdapter listRowAdapter = new ArrayObjectAdapter(cardPresenter); List<Movie> list = entry.getValue(); for (int j = 0; j < list.size(); j++) { listRowAdapter.add(list.get(j)); } HeaderItem header = new HeaderItem(i, entry.getKey(), null); i++; mRowsAdapter.add(new ListRow(header, listRowAdapter)); } HeaderItem gridHeader = new HeaderItem(i, getString(R.string.more_samples), null); GridItemPresenter gridPresenter = new GridItemPresenter(); ArrayObjectAdapter gridRowAdapter = new ArrayObjectAdapter(gridPresenter); gridRowAdapter.add(getString(R.string.grid_view)); gridRowAdapter.add(getString(R.string.error_fragment)); gridRowAdapter.add(getString(R.string.personal_settings)); mRowsAdapter.add(new ListRow(gridHeader, gridRowAdapter)); setAdapter(mRowsAdapter); updateRecommendations(); } ~~~ ### 創建一個卡片視圖 在這步中,你將用view holder創建一個卡片presenter來為卡片視圖呈現媒體項目。注意,每個presenter只能創建一個view類別。如果你有倆個不同的卡片視圖,你就得創建倆個不同的presenter 在[presenter](http://developer.android.com/reference/android/support/v17/leanback/widget/Presenter.html)實現[onCreateViewHolder](http://developer.android.com/reference/android/support/v17/leanback/widget/Presenter.html#onCreateViewHolder(android.view.ViewGroup))時創建一個可以呈現內容項目的view holder。 ~~~ @Override public class CardPresenter extends Presenter { private Context mContext; private static int CARD_WIDTH = 313; private static int CARD_HEIGHT = 176; private Drawable mDefaultCardImage; @Override public ViewHolder onCreateViewHolder(ViewGroup parent) { mContext = parent.getContext(); mDefaultCardImage = mContext.getResources().getDrawable(R.drawable.movie); ... ~~~ 在[onCreateViewHolder](http://developer.android.com/reference/android/support/v17/leanback/widget/Presenter.html#onCreateViewHolder(android.view.ViewGroup))方法中,創建呈現內容的卡片視圖。下面的例子用的是[ImageCardView](http://developer.android.com/reference/android/support/v17/leanback/widget/ImageCardView.html) 當卡片被選中時,默認的行為是放大展開。如果你想創建不同顏色的卡片可以向下面這樣調用[setSelected](http://developer.android.com/reference/android/support/v17/leanback/widget/BaseCardView.html#setSelected(boolean))方法中實現。 ~~~ ... ImageCardView cardView = new ImageCardView(mContext) { @Override public void setSelected(boolean selected) { int selected_background = mContext.getResources().getColor(R.color.detail_background); int default_background = mContext.getResources().getColor(R.color.default_background); int color = selected ? selected_background : default_background; findViewById(R.id.info_field).setBackgroundColor(color); super.setSelected(selected); } }; ... ~~~ 當用戶打開你的應用時,[Presenter.ViewHolder ](http://developer.android.com/reference/android/support/v17/leanback/widget/Presenter.ViewHolder.html)為內容項目顯示了卡片視圖。你需要調用[setFocusable(true) ](http://developer.android.com/reference/android/view/View.html#setFocusable(boolean))和[setFocusableInTouchMode(true)](http://developer.android.com/reference/android/view/View.html#setFocusableInTouchMode(boolean))方法設置接收來自D-pad的焦點控制。 ~~~ ... cardView.setFocusable(true); cardView.setFocusableInTouchMode(true); return new ViewHolder(cardView); } ~~~ 當用戶選中[ImageCardView](http://developer.android.com/reference/android/support/v17/leanback/widget/ImageCardView.html)時,它用你制定的顏色背景展開文字內容,就像下面這樣。