第一行代码学习3(10)

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新闻界面的Fragment实现


先添加一个准备好的新闻实体类,News。

public calss News{    pirvate String title;    private String content;    public News(String title, String content){        this.title = title;        this.content = content;    }    public void setTitle(String title){        this.title = title;    }    public void setContent(String content){        this.content = content;    }    public String getTitle(){        return title;    }    public String getContent(){        return content;    }}

因为标题肯定是一个列表形式的存在所以要用listview显示内容,接下来先配置子项的标题布局,news_item.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/news_title"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:singleLine="true"        android:ellipsize="end"        android:text="18sp"        android:paddingLeft="10dp"        android:paddingRight="10dp"        android:paddingTop="15dp"        android:paddingBottom="15dp"/></LinearLayout>

其中android:padding 表示给控件的周围加上补白,这样不至于内容会紧靠在边缘上。
android:singleLine 设置为true表示让这个TextView只能单行显示。
android:ellipsize 用于设定当文本内容超过控件宽度时,文本的缩略方式,这里指定成end表示在尾部进行缩略。

接下来创建新闻列表的适配器,因为新闻列表的格式是listview,需要用适配器去配置内容(适配器是配置能给用户看得见的内容,意会,因为我总是不能理解适配器的主要作用)。

public class NewsAdapter extends ArrayAdapter<News>{    private int resourceId;    public NewsAdapter(Context context, int textViewResourceId, List<News> objects) {        super(context, textViewResourceId, objects);        resourceId = textViewResourceId;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        News news = getItem(position);        View view;        if(convertView == null){            view = LayoutInflater.from(getContext()).inflate(resourceId, null);        }else{            view = convertView;        }        TextView newTitleText = (TextView)view.findViewById(R.id.news_title);        newTitleText.setText(news.getTitle());        return view;    }}

注意这里的指定泛型要是News.
接下来是新闻内容的代码,新建布局news_content_frag.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <LinearLayout         android:id="@+id/visibility_layout"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:orientation="vertical"        android:visibility="invisible">        <TextView             android:id="@+id/news_title"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:gravity="center"            android:padding="10dp"            android:textSize="20sp"/>        <ImageView             android:layout_width="match_parent"            android:layout_height="1dp"            android:scaleType="fitXY"            android:src="@drawable/line"/>        <TextView             android:id="@+id/new_content"            android:layout_width="match_parent"            android:layout_height="0dp"            android:layout_weight="1"            android:padding="15dp"            android:textSize="18sp"/>    </LinearLayout>    <ImageView        android:layout_width="1dp"        android:layout_height="match_parent"        android:layout_alignParentLeft="true"        android:scaleType="fitXY"        android:src="@drawable/line"/></RelativeLayout>

这里要注意android:scaleType属性设置为fitXY,表示让这张图片充满整个控件的大小。
接下来新建一个NewsContentFragment类用来获取新闻内容布局的实例,并做刷新。

public class NewsContentFragment extends Fragment{    private View view;    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {        view = inflater.inflate(R.layout.news_content_frag, container, false);        return view;    }    /**     * 首先在 onCreateView()方法里加载了我们刚刚创建的 news_content_frag 布局,这个没什        么好解释的。接下来又提供了一个 refresh()方法,这个方法就是用于将新闻的标题和内容显        示在界面上的。可以看到,这里通过 findViewById()方法分别获取到新闻的标题和内容控件,        然后将方法传递进来的参数设置进去     * @param newtitle     * @param newsContent     */    public void refresh(String newtitle, String newsContent){        View visibilityLayout = view.findViewById(R.id.visibility_layout);        visibilityLayout.setVisibility(View.VISIBLE);        TextView newTitleText = (TextView)view.findViewById(R.id.news_title);        TextView newContentText = (TextView)view.findViewById(R.id.new_content);        newTitleText.setText(newtitle);        newContentText.setText(newsContent);    }}

接下来新建新闻内容fragment的布局news_content.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <fragment         android:id="@+id/news_content_fragment"        android:name="com.zhaojy.androidstu_fragmentnewspriacice.NewsContentFragment"        android:layout_width="match_parent"        android:layout_height="match_parent"/></LinearLayout>

接下来新建NewsContentActivity作为显示新闻内容的活动:

public class NewsContentActivity extends Activity{    public static void actionStart(Context context, String newsTitle, String newsContent){        Intent intent = new Intent(context, NewsContentActivity.class);        intent.putExtra("news_title", newsTitle);        intent.putExtra("news_content", newsContent);        context.startActivity(intent);    }    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        requestWindowFeature(Window.FEATURE_NO_TITLE);        setContentView(R.layout.news_content);        String newsTitle = getIntent().getStringExtra("news_title");// 获取传入的新闻标题        String newsContent = getIntent().getStringExtra("news_content");// 获取传入的新闻内容        NewsContentFragment newsContentFragment = (NewsContentFragment) getFragmentManager()                .findFragmentById(R.id.news_content_fragment);//活动获取碎片信息的方式,通过manager的方式获取实例        newsContentFragment.refresh(newsTitle, newsContent);//获取到了实例以后就可以调用碎片里面的方法,刷新NewsContentFragment界面    }}

接下来创建一个用于显示新闻列表的布局,news_title_frag.xml”

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <ListView         android:id="@+id/news_title_list_view"        android:layout_width="match_parent"        android:layout_height="match_parent">    </ListView></LinearLayout>

为以上的listView设置使用的对象,该对象是一个碎片,接下来创建一个碎片加载该布局:

public class NewsTitleFragment extent Fragment implement OnItemClickListener{    private ListView newsTitleView;    private List<News> newsList;    private NewsAdapter adapter;    private boolean isTwoPane;}@Overridepublic void onAttach(Activity activity){    super.onAttach(activity);    newsList = getNews();//初始化新闻标题、内容的数据    adapter = new NewsAdapter(activity, R.layout.news_item, newsList);}@Overridepublic view onCreateView(LayoutInflater inflater, ViewGroup container, Bundle saveInstanceState){    View view = infalter.inflate(R.layout.news_title_frag, container, false);    newsTitleListView = (ListView)view.findViewById(R.id.news_title_list_view);    newsTitleListView = setAdapter(adapter);    newsTitleListView.setOnItemClickListener(this);    return view;}@Overridepublic void onActivityCreate(Bundle savedInstanceState){    super.onActivityCreated(savedInstanceState);    if(getActivity().findViewById(R.id.news_content_layout) != null){        isTwoPane = true;    }else{        isTwoPane = false;    }}@Overridepublic void onItemClick(AdapterView<?> parent, View view, int position, long id){    News news = newsList.get(position);    if(isTwoPane){        NewsContentFragment newsContentFragment = (NewsContentFragment)getFragmentManager().findFragmentById(R.is.news_content_fragment);    }else{        NewsContentActivity.actionStart(getActivity(), news.getTitle(), news.getContent());    }}    private List<News> getNews() {        List<News> newsList = new ArrayList<News>();        News news1 = new News("Succeed in College as a Learning Disabled Student","College freshmen will soon learn to live with a"                + "roommate, adjust to a new social scene and survive less-than-stellar"                + "dining hall food. Students with learning disabilities will face these"                + "transitions while also grappling with a few more hurdles.");//      news1.setTitle("Succeed in College as a Learning Disabled Student");//      news1.setContent("College freshmen will soon learn to live with a"//      + "roommate, adjust to a new social scene and survive less-than-stellar"//      + "dining hall food. Students with learning disabilities will face these"//      + "transitions while also grappling with a few more hurdles.");        newsList.add(news1);        News news2 = new News("Google Android exec poached by China's Xiaomi","China's Xiaomi has poached a key Google executive"                + "involved in the tech giant's Android phones, in a move seen as a coup"                + "for the rapidly growing Chinese smartphone maker.");//      news2.setTitle("Google Android exec poached by China's Xiaomi");//      news2.setContent("China's Xiaomi has poached a key Google executive"//      + "involved in the tech giant's Android phones, in a move seen as a coup"//      + "for the rapidly growing Chinese smartphone maker.");        newsList.add(news2);        return newsList;        }

该类用到了几个fragment的生命周期,其中onAttach()方法最先执行的时候做数据的初始化操作,getNews()获取模拟新闻的数据,以及完成NewsAdapter的创建。在onCreateView()这个我们很熟悉的方法当中加载碎片布局,并给新闻列表注册点击事件。接下来在onActivityCreate()方法中通过寻找单双页的一个标志news_content_layout的View来判断单双页模式,如果是双页,就通过getFragmentManager()找到碎片的id并实例化,调用刷新方法去刷新界面,如果是单页就启动另一个显示的活动。
接下来修改activity_main.xml的代码:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent">    <fragment         android:id="@+id/news_title_fragment"        android:name="com.zhaojy.androidstu_fragmentnewspriacice.NewsTitleFragment"        android:layout_width="match_parent"        android:layout_height="match_parent"/></LinearLayout>

为双页模式设置动态加载布局,建立layout-sw600dp的文件夹,里面同样建立activity_main的xml布局文件,但是代码如下:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <fragment         android:id="@+id/news_title_fragment"        android:name="com.zhaojy.androidstu_fragmentnewspriacice.NewsTitleFragment"        android:layout_width="0dp"        android:layout_height="match_parent"        android:layout_weight="1"/>    <FrameLayout         android:id="@+id/news_content_layout"        android:layout_width="0dp"        android:layout_height="match_parent"        android:layout_weight="3">        <fragment             android:id="@+id/news_content_fragment"            android:name="com.zhaojy.androidstu_fragmentnewspriacice.NewsContentFragment"            android:layout_width="match_parent"            android:layout_height="match_parent"/>    </FrameLayout></LinearLayout>

这样就完成了一个可以自动适配屏幕的新闻查看器。

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