片段中的 GoogleMap V2 在片段重新加载时停止正常工作

Question

我有一个带有两个片段的 DrawerLayout，其中一个有一个 GoogleMap。在启动时，地图可以正常工作。但是，如果我切换到第二个片段并将 nswitch 切换回第一个片段，或者如果发生方向更改，则地图会丢失地图右上角的“缩放到我的位置”按钮，并且不会显示我的位置蓝点和精度半径。但是我仍然可以显示地图，并且可以用 mu 手指放大和缩小。我在我的代码中做错了吗？我该如何解决这个问题？

主要活动

public class MainActivity extends Activity {
    private DrawerLayout mDrawerLayout;
    private ListView mDrawerList; 
    private ActionBarDrawerToggle mDrawerToggle; 
    public static FragmentManager mapFragmentManager;
    private CharSequence mDrawerTitle;

    private CharSequence mTitle;

    private String[] navMenuTitles;
    private TypedArray navMenuIcons;

    private ArrayList<NavDrawerItem> navDrawerItems;
    private NavDrawerListAdapter adapter;

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

        mTitle = mDrawerTitle = getTitle();
        mapFragmentManager = getFragmentManager();
        navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);

        navMenuIcons = getResources()
                .obtainTypedArray(R.array.nav_drawer_icons);

        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.list_slidermenu);

        navDrawerItems = new ArrayList<NavDrawerItem>();

        navDrawerItems.add(new NavDrawerItem(navMenuTitles[0], navMenuIcons.getResourceId(0, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[1], navMenuIcons.getResourceId(1, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[2], navMenuIcons.getResourceId(2, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[3], navMenuIcons.getResourceId(3, -1), true, "22"));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[4], navMenuIcons.getResourceId(4, -1)));
        navDrawerItems.add(new NavDrawerItem(navMenuTitles[5], navMenuIcons.getResourceId(5, -1), true, "50+"));


        navMenuIcons.recycle();

        mDrawerList.setOnItemClickListener(new SlideMenuClickListener());

        adapter = new NavDrawerListAdapter(getApplicationContext(), navDrawerItems);
        mDrawerList.setAdapter(adapter);

        // enabling action bar app icon and behaving it as toggle button
        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);

        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
                R.drawable.ic_drawer, //nav menu toggle icon
                R.string.app_name, // nav drawer open - description for accessibility
                R.string.app_name // nav drawer close - description for accessibility
        ) {
            public void onDrawerClosed(View view) {
                getActionBar().setTitle(mTitle);
                invalidateOptionsMenu();
            }

            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle(mDrawerTitle);
                invalidateOptionsMenu();
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);

        if (savedInstanceState == null) {
            displayView(0);
        }
    }

    private class SlideMenuClickListener implements
            ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
            // display view for selected nav drawer item
            displayView(position);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        switch (item.getItemId()) {
        case R.id.action_settings:
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // if nav drawer is opened, hide the action items
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
        menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
        return super.onPrepareOptionsMenu(menu);
    }


    private void displayView(int position) {
        // update the main content by replacing fragments
        Fragment fragment = null;
        switch (position) {
        case 0:
            fragment = new HomeFragment();
            break;
        case 1:
            fragment = new SecondFragment();
            break;

        default:
            break;
        }

        if (fragment != null) {
            FragmentManager fragmentManager = getFragmentManager();
            fragmentManager.beginTransaction().replace(R.id.frame_container, fragment).commit();
            // update selected item and title, then close the drawer
            mDrawerList.setItemChecked(position, true);
            mDrawerList.setSelection(position);
            setTitle(navMenuTitles[position]);
            mDrawerLayout.closeDrawer(mDrawerList);
        } else {
            // error in creating fragment
            Log.e("MainActivity", "Error in creating fragment");
        }
    }

    @Override
    public void setTitle(CharSequence title) {
        mTitle = title;
        getActionBar().setTitle(mTitle);
    }



    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        mDrawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

}

首页片段

public  class HomeFragment extends Fragment{
    public HomeFragment() { }
    private View view;
    public static GoogleMap mMap;
    static LocationManager locationManager;
    Context con;
    static Double latitude;
    static Double longitude;
    boolean gotCategories=false;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
        if (container == null) { return null;  }

        if(view==null){ 
            view = (View) inflater.inflate(R.layout.map_fragment, container, false);
        }
        con = getActivity();


        setUpMapIfNeeded(); 

        return view;
    }

    public static void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            // Try to obtain the map from the SupportMapFragment.
            mMap = ((MapFragment) MainActivity.mapFragmentManager.findFragmentById(R.id.location_map))
                    .getMap();
            // Check if we were successful in obtaining the map.
            if (mMap != null) {
                mMap.setMyLocationEnabled(true);
            }
        }
    } 

    @Override
    public void onResume() {
        super.onResume();
         setUpMapIfNeeded(); 
    }

    @Override
    public void onDestroyView() {
        // TODO Auto-generated method stub
        super.onDestroyView();
        try{MainActivity.mapFragmentManager.beginTransaction().remove(MainActivity.mapFragmentManager.findFragmentById(R.id.location_map)).commit();
        }catch(Exception e){}
    }

}

Answer 1

像往常一样，我在发布问题后立即找到了答案...... 在 onDestroyView 我添加了 mMap=null;线......所以现在 setUpMapIfNeeded 函数将再次运行并再次实例化地图，并且会像新的一样好。希望这可以帮助某人

@Override
    public void onDestroyView() {
        // TODO Auto-generated method stub
        super.onDestroyView();
        try{MainActivity.mapFragmentManager.beginTransaction().remove(MainActivity.mapFragmentManager.findFragmentById(R.id.location_map)).commit();
        }catch(Exception e){}
        mMap = null;
    }