碎片最佳实践-简易版的新闻应用

先上成果图

小屏幕小屏幕

点击后点击后
大屏幕Nexus7大屏幕Nexus7
点击后点击后

主体思想

写两个activity_main布局文件，一个在layout文件夹下，另一个置于layout-sw600dp下。前者只有一个titleFragment碎片，后者还会加上contentFragment碎片，系统根据设备大小加载不同的activity_main。但是也由于两种布局下都包含titleFragment碎片，在点击ListView时，面临两种选择。其一，若为单页模式，就跳转到包含内容布局的活动。若为双页，获取右碎片实例(getFragmentManager.findFragmentById)，refresh下即可。至于如何判断当前处于单页还是双页，两个activity_main不同的就是大屏幕的多了一个右侧碎片，给这个碎片加上id,在titleFragment中的onActivityCreated(活动加载完成才执行的函数) 用getActivity().findViewById(右侧碎片的id)来判断。getActivity是获取与该碎片相关联的活动

遇到的问题

  1. 继承自android.app.Fragment的碎片类，里面的onAttach(Context context) 在API23中
    不会被调用，导致里面的初始化操作不会执行

解决办法: 将onAttach()中代码转移进onCreateView()

  1. 代码无异常，运行时抛出ActivityNotFound异常

解决办法：在AndroidManifest下注册活动

上代码

代码结构

结构结构

News.class

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public class News {

    private String title;
    private String 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;
    }
}

NewsAdapter.class

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public class NewsAdapter extends ArrayAdapter<News>{

    private int resourceId;

    private View view;

    private ViewHolder viewHolder;

    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);
        if(convertView == null){
            view = LayoutInflater.from(getContext()).inflate(resourceId,null);
            viewHolder = new ViewHolder();
            viewHolder.titleTextView = (TextView) view.findViewById(R.id.title_item_tv);
            view.setTag(viewHolder);
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();
        }

        viewHolder.titleTextView.setText(news.getTitle());
        return view;
    }

    class ViewHolder{
        TextView titleTextView;
    }
}

NewsContentFragment.class

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public class NewsContentFragment extends Fragment{

    private View view;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.content_frag,container,false);
        return view;
    }

    public void refresh(String title, String content){
        LinearLayout linearLayout = (LinearLayout) view.findViewById(R.id.content);
        linearLayout.setVisibility(View.VISIBLE);
        TextView title_tv = (TextView) view.findViewById(R.id.tv_title);
        TextView content_tv = (TextView) view.findViewById(R.id.tv_content);
        title_tv.setText(title);
        content_tv.setText(content);
    }

}

NewsTitleFragment.class

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public class NewsTitleFragment extends Fragment implements AdapterView.OnItemClickListener{

    private List<News> newsList = new ArrayList<News>();

    private Boolean twoPane;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        initData();
        NewsAdapter adapter = new NewsAdapter(getActivity(),R.layout.title_item,newsList);
        View view = inflater.inflate(R.layout.newstitle_frag,container,false);
        ListView NewsTitleListView = (ListView) view.findViewById(R.id.title_list_view);
        NewsTitleListView.setAdapter(adapter);
        NewsTitleListView.setOnItemClickListener(this);
        return view;
    }

    public void initData(){
        News news1 = new News();
        news1.setTitle("Google will accept Gaby to be the CEO");
        news1.setContent("To reduce housing inventories, more migrant rural workers should be issued with urban-residency permits, which will allow them to purchase housing in cities, according to a statement released after a meeting of the Political Bureau of the CPC Central Committee presided over by President ***.");
        newsList.add(news1);

        News news2 = new News();
        news2.setTitle("High-tech products at Light of the Internet Expo Baidu 'self-driving' cars to hit roads in 3 years");
        news2.setContent("Baidu indicated that the new business unit will focus on research and development of self-driving technology as well as build the industrial chain to support the production of next-generation cars.");
        newsList.add(news2);

        News news3 = new News();
        news3.setContent("In the future, vehicles could be self-driven and controlled by smart systems. We have set a target to commercialize our operations in the next three years,\" he said, adding that in 10 years, about 80 percent of the newly produced vehicles would be equipped with self-driving technologies");
        news3.setTitle("Reasonable economomic growth rate targeted");
        newsList.add(news3);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if(getActivity().findViewById(R.id.content_frag_layout) == null){
            twoPane = false;
        } else{
            twoPane = true;
        }
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        News news = newsList.get(position);
        if(twoPane){
            NewsContentFragment newsContentFragment = (NewsContentFragment) getFragmentManager().findFragmentById(R.id.content_frag_layout);
            newsContentFragment.refresh(news.getTitle(), news.getContent());
        } else{
            contentActivity.actionStart(getActivity(),news.getTitle(),news.getContent());
        }
    }
}

content_frag.xml

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:visibility="invisible">

        <TextView
            android:id="@+id/tv_title"
            android:textSize="20sp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="10dp"/>

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="1dp"
            android:src="@drawable/vandh"
            android:scaleType="fitXY"/>

        <TextView
            android:id="@+id/tv_content"
            android:textSize="20sp"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:padding="15dp"/>
    </LinearLayout>

    <ImageView
        android:layout_width="1dp"
        android:layout_height="match_parent"
        android:src="@drawable/vandh"
        android:layout_alignParentLeft="true"/>
</RelativeLayout>

newsTitle_frag.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:id="@+id/title_list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></ListView>
</LinearLayout

title_item.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/title_item_tv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:singleLine="true"
        android:ellipsize="end"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"
        android:paddingTop="15dp"
        android:paddingBottom="15dp"/>
</LinearLayout>

content.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <fragment
        android:id="@+id/content_alone"
        android:name="com.example.gaby.fragmentbestpacticey.NewsContentFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout

layout-anctivity_main

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <fragment
        android:id="@+id/title_frag"
        android:name="com.example.gaby.fragmentbestpacticey.NewsTitleFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</RelativeLayout>

layout-sw600dp-activity_main

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<?xml version="1.0" encoding="utf-8"?>
<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.example.gaby.fragmentbestpacticey.NewsTitleFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"/>

    <fragment
        android:id="@+id/content_frag_layout"
        android:name="com.example.gaby.fragmentbestpacticey.NewsContentFragment"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="3"
        />

</LinearLayout>
posted @ 2016-03-20 22:03  Gabyler  阅读(489)  评论(0)  编辑  收藏  举报