android - getActionProvider : item does not implement SupportMenuItem

Question

我正在尝试在 fragment 的上下文操作栏中使用支持库来实现 ShareActionProvider。我在正常操作栏( onCreateOptionsMenu() )中实现它时没有遇到任何问题，但是当我在 CAB 中尝试它时( MultiModeListener 接口(interface)中的 onCreateActionMode() )，我收到错误:

getActionProvider: item does not implement SupportMenuItem; returning null

在 https://cells-source.cs.columbia.edu/plugins/gitiles/platform/frameworks/support/+/30837f1095c803f332f4a1c3f0917c8afdd50156/v4/java/android/support/v4/view/MenuItemCompat.java 查看 Android 源代码，问题似乎是因为我的 MenuItem 不是 SupportMenuItem 的实例:

 public static ActionProvider getActionProvider(MenuItem item) {
    if (item instanceof SupportMenuItem) {
        return ((SupportMenuItem) item).getSupportActionProvider();
    }

    // TODO Wrap the framework ActionProvider and return it
    Log.w(TAG, "getActionProvider: item does not implement SupportMenuItem; returning null");
    return null;
}

关于如何解决这个问题有什么想法吗？

list :

<activity
            android:name=".myactivity_ActionBarActivity"
            android:theme="@style/Theme.AppCompat.Light"
            android:windowSoftInputMode="stateUnchanged">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                </intent-filter>
            </activity>

Activity :

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;

public class myactivity_ActionBarActivity extends ActionBarActivity{
    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.actionbaractivity_layout); //loads a fragment

    }
}

fragment :

import android.support.v7.widget.ShareActionProvider;
import android.support.v4.view.MenuItemCompat;
import android.view.MenuItem;
import android.view.Menu;
import android.support.v4.app.Fragment;

...
...

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    ...
    ...
    //Handle Action mode events
    myListView.setMultiChoiceModeListener(new MultiChoiceModeListener() {
        private ShareActionProvider mShareActonProvider;
        ....
        ....
        @Override
        public boolean onCreateActionMode(ActionMode mode,
        Menu menu) {
            MenuInflater inflater = mode.getMenuInflater();
            inflater.inflate(R.menu.chatsession_contextmenu, menu);

            //get the ShareActionProvider from the menu item
            MenuItem item = menu.findItem(R.id.share_menu);
            mShareActonProvider = (ShareActionProvider) MenuItemCompat.getActionProvider(item);

            return true;
        }
    }

    ...
    ...
}

菜单布局文件:

<?xml version="1.0" encoding="utf-8" ?>
    <menu xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:myapp="http://schemas.android.com/apk/res-auto">
        <item
            android:id="@+id/delete_menu"
            android:title="Delete message"
            myapp:showAsAction="ifRoom|withText"
            android:icon="@drawable/ic_action_discard">
        </item>

        <item
            android:id="@+id/share_menu"
            android:title="Share message"
            myapp:showAsAction="ifRoom|withText"
            android:icon="@drawable/ic_action_share"
            myapp:actionProviderClass="android.support.v7.widget.ShareActionProvider">
            </item>

    </menu>

编辑 1:

问题的根源似乎是作为参数传递给 onCreateActionMode(ActionMode mode, Menu menu) 和 的 Menu 对象的差异onCreateOptionsMenu(菜单菜单，MenuInflater 充气器)。只有 onCreateOptionsMenu 中的那个有 MenuWrapperICS。这是 Debug模式下两个对象的屏幕截图:

onCreateActionMode(ActionMode mode, Menu menu) :

onCreateOptionsMenu(Menu menu, MenuInflater inflater) :

Answer 1

问题在于 MultipleModeListener 接口(interface)扩展了 android.view.ActionMode.Callback，如源代码所示 http://androidxref.com/4.4.2_r2/xref/frameworks/base/core/java/android/widget/AbsListView.java#6301 .如果您使用支持库中的 ShareActionProvider，则需要 android.support.v7.view.ActionMode.Callback。

解决方案是创建您自己的 ActionMode.CallBack 实现，而不是使用框架的 MultipleModeListener。通过这种方式，您可以确保在需要的地方使用支持库。

例如:

1. 在您的 fragment 中导入 v7 版本的 ActionMode 和 ActionBarActivity

   import android.support.v7.view.ActionMode;
   import android.support.v7.app.ActionBarActivity;
   

2. 为您的 ListView 创建一个 onClickListener 并使用 startSupportActionMode 启动您的自定义 ActionMode.CallBack 实现

   myListView.setItemsCanFocus(false);
   myListView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
   actionMode = null;
   myListView.setOnItemClickListener(new OnItemClickListener(){
       @Override
       public void onItemClick(AdapterView<?> parent, View view, int position, long id){
                   if(myListView.getCheckedItemCount() == 0){
                       actionMode.finish();
                       return;
                   }
   
                       if(actionMode == null){
                           actionMode = ((ActionBarActivity)getActivity()).startSupportActionMode(new ContextualActionBar());
                       }
   
               }
           });
   

3. 创建自定义 ActionMode.Callback 实现

   private class ContextualActionBar implements ActionMode.Callback{
       private ShareActionProvider mShareActionProvider;
   
       @Override
       public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
           switch(item.getItemId()){
   
           case R.id.share_menu :
               mode.finish();
               return true;
   
           default :
               return false;
           }
       }
   
       @Override
       public boolean onCreateActionMode(ActionMode mode, Menu menu) {
           MenuInflater inflater = mode.getMenuInflater();
           inflater.inflate(R.menu.chatsession_contextmenu, menu);
   
           //Initialize the ShareActionProvider
           MenuItem shareMenuItem = menu.findItem(R.id.share_menu);
           mShareActionProvider = (ShareActionProvider) MenuItemCompat.getActionProvider(shareMenuItem);
           Intent shareIntent = new Intent(Intent.ACTION_SEND);
           shareIntent.setType("text/plain");
           shareIntent.putExtra(Intent.EXTRA_TEXT, "test message");
           mShareActionProvider.setShareIntent(shareIntent);
           return true;
       }
   
       @Override
       public void onDestroyActionMode(ActionMode mode) {
           //Nullify the actionMode object 
           //so that the onClickListener can identify whether the ActionMode is ON  
           actionMode = null;
   
           //Uncheck all checked messages 
           SparseBooleanArray selectedItems = myListView.getCheckedItemPositions();
           for(int i=0;i<selectedItems.size();i++){
               myListView.setItemChecked(selectedItems.keyAt(i), false);
           }
       }
   
       @Override
       public boolean onPrepareActionMode(ActionMode arg0, Menu arg1) {
           // TODO Auto-generated method stub
           return false;
       }
   
   }