android Fragments详解【2】

梦里梦外; 2022-01-15 04:17 155阅读 0赞

相就的XML文件：

![复制代码][copycode.gif]

<? 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"   
    android:orientation ="horizontal"   >  
  
    < fragment  class ="com.xuzhi.fragment.FragmentDemoActivity$TitlesFragment"  android:id ="@+id/titles"  android:layout\_weight ="1"   
       android:layout\_width ="0px"  android:layout\_height ="match\_parent"   
        />  
     
    < FrameLayout  android:id ="@+id/details"  android:layout\_weight ="1"  android:layout\_width ="0px"  android:layout\_height ="match\_parent"   
       android:background ="?android:attr/detailsElementBackground"   
        ></ FrameLayout >  
</ LinearLayout >

![复制代码][copycode.gif]

主界面代码（己做注释）：

![复制代码][copycode.gif]

package  com.xuzhi.fragment;  
import android.app.Activity;  
import android.app.AlertDialog;  
import android.app.Fragment;  
import android.app.FragmentTransaction;  
import android.app.ListFragment;  
import android.os.Bundle;  
import android.util.TypedValue;  
import android.view.LayoutInflater;  
import android.view.View;  
import android.view.ViewGroup;  
import android.widget.ArrayAdapter;  
import android.widget.ListView;  
import android.widget.ScrollView;  
import android.widget.TextView;  
  
public  class FragmentDemoActivity  extends Activity \{  
  
     public  static String\[\] array = \{ "text1,", "text2", "text3", "text4",  
            "text5,", "text6", "text7", "text8" \};  
  
     /\*\*  Called when the activity is first created.  \*/  
    @Override  
     public  void onCreate(Bundle savedInstanceState) \{  
         super.onCreate(savedInstanceState);   
        setContentView(R.layout.main);  
    \}  
  
          
     public  static  class TitlesFragment  extends ListFragment \{  
  
         boolean mDualPane;  
         int mCurCheckPosition = 0;  
          
        @Override  
         public  void onCreate(Bundle savedInstanceState) \{  
             //  TODO Auto-generated method stub   
             super.onCreate(savedInstanceState);  
            System.out.println("Fragment-->onCreate");  
        \}  
          
        @Override  
         public View onCreateView(LayoutInflater inflater, ViewGroup container,  
                Bundle savedInstanceState) \{  
             //  TODO Auto-generated method stub   
            System.out.println("Fragment-->onCreateView");  
             return  super.onCreateView(inflater, container, savedInstanceState);  
        \}  
          
        @Override  
         public  void onPause() \{  
             //  TODO Auto-generated method stub   
             super.onPause();  
            System.out.println("Fragment-->onPause");  
        \}  
          
          
        @Override  
         public  void onStop() \{  
             //  TODO Auto-generated method stub   
             super.onStop();  
              
            System.out.println("Fragment-->onStop");  
        \}  
          
        @Override  
         public  void onAttach(Activity activity) \{  
             //  TODO Auto-generated method stub   
             super.onAttach(activity);  
            System.out.println("Fragment-->onAttach");  
        \}  
          
        @Override  
         public  void onStart() \{  
             //  TODO Auto-generated method stub   
             super.onStart();  
            System.out.println("Fragment-->onStart");  
        \}  
          
        @Override  
         public  void onResume() \{  
             //  TODO Auto-generated method stub   
             super.onResume();  
            System.out.println("Fragment-->onResume");  
        \}  
          
        @Override  
         public  void onDestroy() \{  
             //  TODO Auto-generated method stub   
             super.onDestroy();  
            System.out.println("Fragment-->onDestroy");  
        \}  
          
          
  
        @Override  
         public  void onActivityCreated(Bundle savedInstanceState) \{  
             //  TODO Auto-generated method stub   
             super.onActivityCreated(savedInstanceState);  
            System.out.println("Fragment-->onActivityCreted");  
            setListAdapter( new ArrayAdapter<String>(getActivity(),  
                    android.R.layout.simple\_list\_item\_1, array));  
  
            View detailsFrame = getActivity().findViewById(R.id.details);  
  
            mDualPane = detailsFrame !=  null  
                    && detailsFrame.getVisibility() == View.VISIBLE;  
  
             if (savedInstanceState !=  null) \{  
                mCurCheckPosition = savedInstanceState.getInt("curChoice", 0);  // 从保存的状态中取出数据   
            \}  
  
             if (mDualPane) \{  
                getListView().setChoiceMode(ListView.CHOICE\_MODE\_SINGLE);  
  
                showDetails(mCurCheckPosition);  
            \}  
        \}  
  
        @Override  
         public  void onSaveInstanceState(Bundle outState) \{  
             //  TODO Auto-generated method stub   
             super.onSaveInstanceState(outState);  
  
            outState.putInt("curChoice", mCurCheckPosition); // 保存当前的下标   
        \}  
  
        @Override  
         public  void onListItemClick(ListView l, View v,  int position,  long id) \{  
             //  TODO Auto-generated method stub   
             super.onListItemClick(l, v, position, id);  
            showDetails(position);  
        \}  
  
         void showDetails( int index) \{  
            mCurCheckPosition = index;   
             if (mDualPane) \{  
                getListView().setItemChecked(index,  true);  
                DetailsFragment details = (DetailsFragment) getFragmentManager()  
                        .findFragmentById(R.id.details);   
                 if (details ==  null || details.getShownIndex() != index) \{  
                    details = DetailsFragment.newInstance(mCurCheckPosition);   
  
                     // 得到一个fragment 事务（类似sqlite的操作）   
                    FragmentTransaction ft = getFragmentManager()  
                            .beginTransaction();  
                    ft.replace(R.id.details, details); // 将得到的fragment 替换当前的viewGroup内容，add则不替换会依次累加   
                    ft.setTransition(FragmentTransaction.TRANSIT\_FRAGMENT\_FADE); // 设置动画效果   
                    ft.commit(); // 提交   
                \}  
            \}  else \{  
                 new AlertDialog.Builder(getActivity()).setTitle(  
                        android.R.string.dialog\_alert\_title).setMessage(  
                        array\[index\]).setPositiveButton(android.R.string.ok,  
                         null).show();  
            \}  
        \}  
    \}  
  
     /\*\*   
     \* 作为界面的一部分，为fragment 提供一个layout  
     \*  @author  terry  
     \*  
      \*/  
     public  static  class DetailsFragment  extends Fragment \{  
  
         public  static DetailsFragment newInstance( int index) \{   
            DetailsFragment details =  new DetailsFragment();  
            Bundle args =  new Bundle();  
            args.putInt("index", index);  
            details.setArguments(args);  
             return details;  
        \}  
  
         public  int getShownIndex() \{  
             return getArguments().getInt("index", 0);  
        \}  
  
        @Override  
         public View onCreateView(LayoutInflater inflater, ViewGroup container,  
                Bundle savedInstanceState) \{  
             //  TODO Auto-generated method stub   
             if (container ==  null)  
                 return  null;  
  
            ScrollView scroller =  new ScrollView(getActivity());  
            TextView text =  new TextView(getActivity());  
  
             int padding = ( int) TypedValue.applyDimension(  
                    TypedValue.COMPLEX\_UNIT\_DIP, 4, getActivity()  
                            .getResources().getDisplayMetrics());  
            text.setPadding(padding, padding, padding, padding);  
            scroller.addView(text);  
  
            text.setText(array\[getShownIndex()\]);  
             return scroller;  
        \}  
    \}  
\}

![复制代码][copycode.gif]

注意：

1.  如果你想在Fragment 里面创建menu，则必须在onCreate的时候设置让它可以存在optionMenu才可以创建，代码为：  
    
    
    ![复制代码][copycode.gif]
    
    public  static  class DetailsFragment  extends Fragment \{  
      
            @Override  
             public  void onCreate(Bundle savedInstanceState) \{  
                 //  TODO Auto-generated method stub   
                 super.onCreate(savedInstanceState);  
                setHasOptionsMenu( true);  
            \}  
    \}
    
    ![复制代码][copycode.gif]
    
    之后的操作即可以像平常Android的menu用法一样,代码为：  
    
    
    ![复制代码][copycode.gif]
    
    @Override  
             public  void onCreateOptionsMenu(Menu menu, MenuInflater inflater) \{  
                 //  TODO Auto-generated method stub   
                 super.onCreateOptionsMenu(menu, inflater);  
                 menu.add("Menu 1a").setShowAsAction(MenuItem.SHOW\_AS\_ACTION\_IF\_ROOM);  
                    menu.add("Menu 1b").setShowAsAction(MenuItem.SHOW\_AS\_ACTION\_IF\_ROOM);  
            \}  
              
            @Override  
             public  boolean onOptionsItemSelected(MenuItem item) \{  
                 //  TODO Auto-generated method stub   
                Toast.makeText(getActivity(), "index is"+getShownIndex()+" && menu text is "+item.getTitle(), 1000).show();  
                 return  super.onOptionsItemSelected(item);  
            \}
    
    ![复制代码][copycode.gif]

更多详细的使用方法，请参考SDK和APIDEMO中相关的例子和解释。

[copycode.gif]: /images/20220115/481d40c13e0a4161adc5983f7b0716fe.png