Android 根据不同的屏幕，加载不同的布局文件 使用refs.xml

Fragment与Activity通信Activity向Fragment传递数据:在Activity中创建Bundle数据包，并调用Fragment的setArguments(Bundle bundle)方法即可将Bundle数据包传给Fragment.Fragment向Activity传递数据或Activity需要在Fragment运行中实时通信:在Fragment中定义一个内部回调接口，再让包含该Fragment的Activity实现该回调接口，这样Fragment即可调用该回调方法将数据传给Activity.Fragment的管理与Fragment事务(Activity管理Fragment主要依靠FragmentManager)FragmentManager可以完成如下几方面功能1.使用findFragmentById(int id)或findFragmentByTag(String tag)方法获取指定Fragment;2.调用popBackStack()方法将Fragment从后台栈中弹出;3.调用addOnBackStackChangeListener()注册一个监听器，用于监听后台栈的变化.public class BookListActivity extends Activity implementsBookListFragment.Callbacks{// 定义一个旗标，用于标识该应用是否支持大屏幕private boolean mTwoPane;@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);// 指定加载R.layout.activity_book_list对应的界面布局文件// 但实际上该应用会根据屏幕分辨率家在不同的界面布局文件/*屏幕适配-->创建values-sw600dp、values-large文件夹，创建refs.xml文件如下<resources><item type="layout" name="activity_book_list">@layout/activity_book_twopane</item></resources>*/setContentView(R.layout.activity_book_list);// 如果加载的界面布局文件中包含ID为book_detail_container的组件if (findViewById(R.id.book_detail_container) != null){mTwoPane = true;((BookListFragment) getFragmentManager().findFragmentById(R.id.book_list)).setActivateOnItemClick(true);}}@Overridepublic void onItemSelected(Integer id){if (mTwoPane){// 创建Bundle，准备向Fragment传入参数Bundle arguments = new Bundle();arguments.putInt(BookDetailFragment.ITEM_ID, id);// 创建BookDetailFragment对象BookDetailFragment fragment = new BookDetailFragment();// 向Fragment传入参数fragment.setArguments(arguments);// 使用fragment替换book_detail_container容器当前显示的FragmentgetFragmentManager().beginTransaction().replace(R.id.book_detail_container, fragment).commit();}else{// 创建启动BookDetailActivity的IntentIntent detailIntent = new Intent(this, BookDetailActivity.class);// 设置传给BookDetailActivity的参数detailIntent.putExtra(BookDetailFragment.ITEM_ID, id);// 启动ActivitystartActivity(detailIntent);}}}activity_book_list.xml<!-- 直接使用BookListFragment作为界面组件 --><fragment xmlns:android="http://schemas.android.com/apk/res/android"android:name="org.crazyit.app.BookListFragment"android:id="@+id/book_list"android:layout_width="match_parent"android:layout_height="match_parent"android:layout_marginLeft="16dp"android:layout_marginRight="16dp"/>activity_book_twopane.xml<!-- 定义一个水平排列的LinearLayout，并指定使用中等分隔条 --><LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"android:orientation="horizontal"android:layout_width="match_parent"android:layout_height="match_parent"android:layout_marginLeft="16dp"android:layout_marginRight="16dp"android:divider="?android:attr/dividerHorizontal"android:showDividers="middle"><!-- 添加一个Fragment --><fragmentandroid:name="org.crazyit.app.BookListFragment"android:id="@+id/book_list"android:layout_width="0dp"android:layout_height="match_parent"android:layout_weight="1" /><!-- 添加一个FrameLayout容器 --><FrameLayoutandroid:id="@+id/book_detail_container"android:layout_width="0dp"android:layout_height="match_parent"android:layout_weight="3" /></LinearLayout>public class BookListFragment extends ListFragment{private Callbacks mCallbacks;public interface Callbacks{public void onItemSelected(Integer id);}@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);// 为该ListFragment设置AdaptersetListAdapter(new ArrayAdapter<BookContent.Book>(getActivity(),android.R.layout.simple_list_item_activated_1,android.R.id.text1, BookContent.ITEMS));  //①}// 当该Fragment被添加、显示到Activity时，回调该方法@Overridepublic void onAttach(Activity activity){super.onAttach(activity);// 如果Activity没有实现Callbacks接口，抛出异常if (!(activity instanceof Callbacks)){throw new IllegalStateException("BookListFragment所在的Activity必须实现Callbacks接口!");}// 把该Activity当成Callbacks对象mCallbacks = (Callbacks) activity;}// 当该Fragment从它所属的Activity中被删除时回调该方法@Overridepublic void onDetach(){super.onDetach();// 将mCallbacks赋为null。mCallbacks = null;}// 当用户点击某列表项时回调该方法@Overridepublic void onListItemClick(ListView listView, View view, int position, long id){super.onListItemClick(listView, view, position, id);mCallbacks.onItemSelected(BookContent.ITEMS.get(position).id);}public void setActivateOnItemClick(boolean activateOnItemClick){getListView().setChoiceMode(activateOnItemClick ? ListView.CHOICE_MODE_SINGLE: ListView.CHOICE_MODE_NONE);}}public class BookDetailActivity extends Activity{@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);// 指定加载/res/layout目录下的activity_book_detail.xml布局文件// 该界面布局文件内只定义了一个名为book_detail_container的FrameLayoutsetContentView(R.layout.activity_book_detail);// 将ActionBar上应用图标转换成可点击的按钮getActionBar().setDisplayHomeAsUpEnabled(true);if (savedInstanceState == null){// 创建BookDetailFragment对象BookDetailFragment fragment = new BookDetailFragment();// 创建Bundle对象，Bundle arguments = new Bundle();arguments.putInt(BookDetailFragment.ITEM_ID, getIntent().getIntExtra(BookDetailFragment.ITEM_ID, 0));// 向Fragment传入参数fragment.setArguments(arguments);// 将指定fragment添加到book_detail_container容器中getFragmentManager().beginTransaction().add(R.id.book_detail_container, fragment).commit();}}@Overridepublic boolean onOptionsItemSelected(MenuItem item){if (item.getItemId() == android.R.id.home){// 创建启动BookListActivity的IntentIntent intent = new Intent(this, BookListActivity.class);// 添加额外的Flag，将Activity栈中处于FirstActivity之上的Activity弹出intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);// 启动intent对应的ActivitystartActivity(intent);return true;}return super.onOptionsItemSelected(item);}}public class BookDetailFragment extends Fragment{public static final String ITEM_ID = "item_id";// 保存该Fragment显示的Book对象BookContent.Book book;@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);// 如果启动该Fragment时包含了ITEM_ID参数if (getArguments().containsKey(ITEM_ID)){book = BookContent.ITEM_MAP.get(getArguments().getInt(ITEM_ID));}}// 重写该方法，该方法返回的View将作为Fragment显示的组件@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){// 加载/res/layout/目录下的fragment_book_detail.xml布局文件View rootView = inflater.inflate(R.layout.fragment_book_detail,container, false);if (book != null){// 让book_title文本框显示book对象的title属性((TextView) rootView.findViewById(R.id.book_title)).setText(book.title);// 让book_desc文本框显示book对象的desc属性((TextView) rootView.findViewById(R.id.book_desc)).setText(book.desc);}return rootView;}}model层public class BookContent{public static class Book{public Integer id;public String title;public String desc;public Book(Integer id, String title, String desc){this.id = id;this.title = title;this.desc = desc;}@Overridepublic String toString(){return title;}}public static List<Book> ITEMS = new ArrayList<Book>();public static Map<Integer, Book> ITEM_MAP = new HashMap<Integer, Book>();static{addItem(new Book(1, "疯狂Java讲义", "一本全面、深入的Java学习图书，已被多家高校选做教材。"));addItem(new Book(2, "疯狂Android讲义", "Android学习者的首选图书，常年占据京东、当当、亚马逊3大网站Android销量排行榜的榜首"));addItem(new Book(3, "轻量级Java EE企业应用实战", "全面介绍Java EE开发的Struts 2、Spring 3、Hibernate 4框架"));}private static void addItem(Book book){ITEMS.add(book);ITEM_MAP.put(book.id, book);}}