OnDetach/onAttach 片段重新创建片段活动

Posted 2023-02-16

【中文标题】OnDetach/onAttach 片段重新创建片段活动

【英文标题】：OnDetach/onAttach fragment recreate fragment activity

【发布时间】：2013-02-21 08:46:13

【问题描述】：

我想分离/附加我的片段，但是如何设置，附加后该片段不会重新创建。

在片段中我有 WebView；当我选择和取消选择标签时，webview 加载起始页。

这是我的代码：

  public class MainActivity extends Activity implements OnClickListener, OnMenuItemClickListener 


    ActionBar bar;
    View v;

     public static TextView tilt;
    LayoutInflater inflater;



    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
        onAddTab();
        View v=getLayoutInflater().inflate(R.layout.action_bar, null);
         ImageButton im = (ImageButton)v.findViewById(R.id.tab_toggle);
        im.setOnClickListener(this);
        getActionBar().setBackgroundDrawable(getResources().getDrawable(R.drawable.shape_layout));
        getActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
        getActionBar().setCustomView(v);
        onToggleTabs();



        

    @Override
    public void onClick(View v) 
        // TODO Auto-generated method stub
        switch (v.getId())
        case R.id.tab_toggle:

            onAddTab();

            break;
        

    

    public void onAddTab() 
        final ActionBar bar = getActionBar();
        View v=getLayoutInflater().inflate(R.layout.layout_tab, null);
        tilt = (TextView)v.findViewById(R.id.tit_le);

        ActionBar.LayoutParams lp = new ActionBar.LayoutParams(ActionBar.LayoutParams.WRAP_CONTENT, ActionBar.LayoutParams.WRAP_CONTENT); 
        lp.gravity = Gravity.CENTER;
        v.setLayoutParams(lp);
        closetab = (ImageButton)v.findViewById(R.id.close);
        closetab.setOnClickListener(new OnClickListener() 

            @Override
            public void onClick(View v) 
                // TODO Auto-generated method stub
                onRemoveTab();


            
        );

        bar.addTab(bar.newTab()
                .setCustomView(v)
                .setTabListener(new TabListener<Web>(this, "Tag A", Web.class)));

    



    public void onRemoveTab() 
        final ActionBar bar = getActionBar();
        Tab tab = bar.getSelectedTab();

            bar.removeTab(tab);

    

    public void onToggleTabs() 
        final ActionBar bar = getActionBar();


            bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);


    

    public void onRemoveAllTabs(View v) 
        getActionBar().removeAllTabs();
    




    public static class TabListener<T extends Fragment>  implements ActionBar.TabListener

       private final Activity myActivity;
       private final String myTag;
       private final Class<T> myClass;

       public TabListener(Activity activity, String tag, Class<T> cls) 
           myActivity = activity;
           myTag = tag;
           myClass = cls;
       

 @Override
 public void onTabSelected(Tab tab, FragmentTransaction ft) 

  Fragment myFragment = myActivity.getFragmentManager().findFragmentByTag(myTag);

  // Check if the fragment is already initialized
        if (myFragment == null) 
            // If not, instantiate and add it to the activity
            myFragment = Fragment.instantiate(myActivity, myClass.getName());
            ft.add(R.id.fragment0, myFragment, myTag);
         else 
            // If it exists, simply attach it in order to show it
            ft.attach(myFragment);
        

 

 @Override
 public void onTabUnselected(Tab tab, FragmentTransaction ft) 

  Fragment myFragment = myActivity.getFragmentManager().findFragmentByTag(myTag);

  if (myFragment != null) 
            // Detach the fragment, because another one is being attached
            ft.detach(myFragment);

        

 

 @Override
 public void onTabReselected(Tab tab, FragmentTransaction ft) 
  // TODO Auto-generated method stub

 
    

有片段：

public class Web extends Fragment implements OnLongClickListener, OnClickListener


@Override
public void onCreate(Bundle savedInstanceState) 
    // TODO Auto-generated method stub

    super.onCreate(savedInstanceState);



@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) 
    // TODO Auto-generated method stub
    c=this.getActivity();

    v = inflater.inflate(R.layout.activity_main, container, false);
    return v;


@SuppressWarnings("deprecation")
@Override
public void onActivityCreated(Bundle savedInstanceState) 
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);
setRetainInstance(true);


wv = (WebView)v.findViewById(R.id.wv);
wv.setWebChromeClient(new WebChromeClient()
    @Override
    public void onProgressChanged(WebView view, int progress) 
        // TODO Auto-generated method stub
        super.onProgressChanged(view, progress);

               if(progress < 100 && pr.getVisibility() == ProgressBar.GONE)
                   pr.setVisibility(ProgressBar.VISIBLE);

               
               pr.setProgress(progress);
               if(progress == 100) 
                   pr.setVisibility(ProgressBar.GONE);

               
            
);
wv.setWebViewClient(new MyWebViewClient());











wv.loadUrl("http://www.google.com");
wv.setOnLongClickListener(this);

【参考方案1】：

试试setRetainInstance(boolean)

还可以查看以下帖子： android fragments setRetainInstance(true) not works (Android support library) Fragment setRetainInstance not works (Android support lib) Understanding Fragment's setRetainInstance(boolean)

【讨论】：

我在 onActivityCreated 中设置了 RetainInstance(true)，但还是同样的问题，Activity 重新创建。

“这只能与不在后台堆栈中的片段一起使用” - 你考虑过这个吗？

我的片段不在后栈中。

但是您写了“活动重新创建”-确实如此，然后没有创建片段。你确定你检查的方式正确吗？