fragment实现横竖屏的切换

1.以新闻布局为例，首先创建新闻标题fragment 和 新闻内容fragment

1)首先创建手机新闻标题的fragment布局文件

fragment_news_list.xml

2)创建手机新闻的fragment

public class NewsListFragment extends Fragment implements AdapterView.OnItemClickListener {
    /*
    * fragment 定义的接口 用于给activity传递一个listview点击事件
    *
    * */
    public  interface  OnNewsSelectedListener{
        void onNewsSelected(Bundle bundle);
    }
    private OnNewsSelectedListener mOnNewsSelectedListener;
    public NewsListFragment() {
        // Required empty public constructor
    }
	//当引用Fragment生命周期的onAttach()方法时，就自动获取MainActivity的上下文，所以不用再通过该方法传递上下文了
   // public  void setOnNewsSelectedListener(OnNewsSelectedListener OnNewsSelectedListener){
   //    mOnNewsSelectedListener = OnNewsSelectedListener;
   // }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        //内部设置 接口回调
        if (context instanceof OnNewsSelectedListener){
            mOnNewsSelectedListener = (OnNewsSelectedListener) context;
        }else {
            throw new IllegalArgumentException("Activity must OnNewsSelectedListener");
        }
    }

    @Override
    public void onDetach() {
        mOnNewsSelectedListener = null;
        super.onDetach();

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View ret = inflater.inflate(R.layout.fragment_news_list, container, false);
        ListView listView = (ListView) ret.findViewById(R.id.news_list);
        //设置点击
        listView.setOnItemClickListener(this);
        if (listView != null){
            ArrayList data = new ArrayList<>();
            for (int i = 0; i < 100; i++) {
                data.add("News" + i);
            }

        ArrayAdapter mAdapter = new ArrayAdapter(
                getContext(),android.R.layout.simple_list_item_1,
                data
        );
            listView.setAdapter(mAdapter);
        }
        return ret;
    }

    @Override
    public void onItemClick(AdapterView parent, View view, int position, long id) {
        if (mOnNewsSelectedListener != null){
            Bundle bundle = new Bundle();
            bundle.putInt("position",position);
            bundle.putLong("id",id);
            mOnNewsSelectedListener.onNewsSelected(bundle);
        }
    }
}

3)创建新闻内容的fragment布局文件

fragment_detail_title.xml

4)创建新闻的内容的fragment

public class DetailFragment extends Fragment {

    private TextView mTextTitle;
    public DetailFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View ret = inflater.inflate(R.layout.fragment_detail, container, false);
        mTextTitle = (TextView)ret.findViewById(R.id.detail_title);

        Bundle arguments = getArguments();
        if (arguments != null){
            long id = arguments.getLong("id");
            mTextTitle.setText("id = " + id);
        }
        return ret;
    }
    public void setDetailTitle(String title){
        mTextTitle.setText(title);
    }

}

2.创建UI线程用来放置fragment，考虑到横屏竖屏的问题，需要创建不同的activity_main.xml布局文件

1)竖屏的布局文件activity_main.xml

2)横屏的布局文件activity_main.xml

3)UI线程的程序代码

public class MainActivity extends AppCompatActivity implements NewsListFragment.OnNewsSelectedListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


    }

    @Override
    public void onNewsSelected(Bundle bundle) {
        Log.d("OnNewsSelected", "bundle: " + bundle);
        FragmentManager manager = getSupportFragmentManager();
        Fragment fragment = manager.findFragmentById(R.id.fragment_detail);
        if (fragment != null && fragment.isVisible()){
            DetailFragment detailFragment = (DetailFragment) fragment;
            detailFragment.setDetailTitle(bundle.toString());
        }else{
            Intent intent = new Intent(this,DetailActivity.class);
            intent.putExtras(bundle);
            startActivity(intent);
        }

    }
}

3.当手机是竖屏状态时，点击listview中的item需要发生跳转，所以需要重新创建新的UI线程

1) 示例代码如下：

public class DetailActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail);
        // 如果 savedInstanceState == null 代表一次创建 否则代表屏幕发生过旋转

        if (savedInstanceState == null) {
            Bundle extras = getIntent().getExtras();
            if (extras != null){

                DetailFragment detailFragment = new DetailFragment();
                //将从UI线程传递过来的bundle ，通过下面的方法传递到fragment中
                detailFragment.setArguments(extras);
                FragmentManager manager = getSupportFragmentManager();
                FragmentTransaction tx = manager.beginTransaction();
                tx.replace(R.id.detail_fragment_container,detailFragment);
                //在事物提交之后 会进入到 fragment的创建的生命周期
                // 不能在这个语句执行的附近
                tx.commit();
            }
        }
    }
}

2)该UI线程的布局文件如下：