我一直在试验android.support.v4.widget.DrawerLayout并有4个片段可供抽屉选择。地图最初加载时没有任何问题，但是当我打开抽屉并更换碎片时，我无法返回地图。我只是得到一个黑屏。 Logcat显示片段已重新创建，但我什么都没得到。只是一个空白的黑屏。我可以毫无问题地在其他片段之间切换。我究竟做错了什么？我的项目的Min API为14。
我从ExploreMap加载MainActivity.java（片段）：
if (position == 0){
ExploreMap exMap = new ExploreMap();
exMap.setRetainInstance(true);
getFragmentManager().beginTransaction().replace(R.id.content_frame, exMap).commit();
}
在ExploreMap.java我执行以下操作
public class ExploreMap extends Fragment implements OnInfoWindowClickListener, android.location.LocationListener, OnMapLongClickListener{
private LocationManager mLocManager;
private GoogleMap mMap;
private MapFragment mMapFragment;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
FragmentManager fm = getActivity().getFragmentManager();
mMapFragment = (MapFragment) fm.findFragmentById(R.id.map);
if (mMapFragment == null) {
mMapFragment = MapFragment.newInstance();
fm.beginTransaction().replace(R.id.map, mMapFragment).commit();
}
if (savedInstanceState == null) {
// First incarnation of this activity.
mMapFragment.setRetainInstance(true);
}else {
// Reincarnated activity. The obtained map is the same map instance in the previous
// activity life cycle. There is no need to reinitialize it.
mMap = mMapFragment.getMap();
}
createMapIfNeeded();
return inflater.inflate(R.layout.explore_map_layout, container, false);
}
@Override
public void onResume() {
super.onResume();
//create the map
createMapIfNeeded();
}
private void createMapIfNeeded(){
if(mLocManager == null){
mLocManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
mLocManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES,
this);
}
//locmanager can return null if no last known locaiton is available.
location = mLocManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
//if a map has not already been instantiated it'll return null
if(mMap == null){
//instantiate map
mMap = mMapFragment.getMap();
//check it has been instantiated
if(mMap != null){
mMap.setOnMapLongClickListener(this);
mMap.setOnInfoWindowClickListener(this);
mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
mMap.setMyLocationEnabled(true);
//Manipulate map here (add coordinates/polylines from trip etc etc.)
UiSettings setting = mMap.getUiSettings();
setting.setTiltGesturesEnabled(true);
setting.setRotateGesturesEnabled(true);
setting.setZoomControlsEnabled(true);
setting.setMyLocationButtonEnabled(true);
if(location != null){
CameraUpdate cu = CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 15);
mMap.animateCamera(cu);
}
}
}
}
XML如下
mainactivity_layout.xml
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- As the main content view, the view below consumes the entire
space available using match_parent in both dimensions. -->
<FrameLayout
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<!-- android:layout_gravity="start" tells DrawerLayout to treat
this as a sliding drawer on the left side for left-to-right
languages and on the right side for right-to-left languages.
The drawer is given a fixed width in dp and extends the full height of
the container. A solid background is used for contrast
with the content view. -->
<ListView
android:id="@+id/left_drawer"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:choiceMode="singleChoice"
android:divider="@android:color/transparent"
android:dividerHeight="0dp"
android:background="#111"/>
</android.support.v4.widget.DrawerLayout>
和exploremap_layout.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<FrameLayout
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
答案 0 :(得分：2)
经过几天的撞击我的头后，我发现了问题，或者我应该说问题。 tsp建议使用上面的库也可以使用，但是我想让它与Google提供的android.support.v4.widget.DrawerLayout一起使用。
问题是2倍。
setRetainInstance(true)，原始MapFragment实例保留在内存中。由于原因，我仍然不完全理解，一旦返回到ExploreMap片段，MapFragment的原始实例就不会重新出现。为了解决这个问题，我在MapFragment最初创建时为其指定了一个名为“mapfrag”的String标记，并将变量设置为public static。接下来在Activity中，抽屉代码用于切换片段，我执行findFragmentByTag()并测试其null，如果它不为null则删除MapFragment。然而＃1只能让你走到一半，因为当你回到ExploreMap时它会重新出现，但是MapFragment中的基础GoogleMap一直向我返回null而我无法获得地图完全配置。
2）我发现了这篇文章MapFragment return null。建议扩展自己的MapFragment并实现一个接口，以便在MapFragment创建完成时通知，几乎可以保证非空的GoogleMap。
和WHAMMY !!你有谷歌抽屉布局工作谷歌地图。这是我完整的工作代码。
MainActivity.java
if (position == 0){
exMap = new ExploreMap();
exMap.setRetainInstance(true);
getFragmentManager().beginTransaction().replace(R.id.content_frame, exMap).commit();
}
if(position == 1){
//remove map frag here instead of in explore map
Fragment f = getFragmentManager().findFragmentByTag("mapfrag");
if(f != null){
getFragmentManager().beginTransaction().remove(f).commit();
}
Ms fragment = new Ms();
getFragmentManager().beginTransaction().replace(R.id.content_frame, fragment).commit();
}
if(position == 2){
Fragment f = getFragmentManager().findFragmentByTag("mapfrag");
if(f != null){
getFragmentManager().beginTransaction().remove(f).commit();
}
Settings fragment = new Settings();
getFragmentManager().beginTransaction().replace(R.id.content_frame, fragment).commit();
}
if(position == 3){
Fragment f = getFragmentManager().findFragmentByTag("mapfrag");
if(f != null){
getFragmentManager().beginTransaction().remove(f).commit();
}
About fragment = new About();
getFragmentManager().beginTransaction().replace(R.id.content_frame, fragment).commit();
}
ExploreMap.java 中的
public class ExploreMap extends Fragment implements MyMapFragment.MapCallback, OnInfoWindowClickListener, android.location.LocationListener, OnMapLongClickListener{
private LocationManager mLocManager;
private GoogleMap mMap;
public static MyMapFragment mMapFragment;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.explore_map_layout, container, false);
FragmentManager fm = getActivity().getFragmentManager();
mMapFragment = (MyMapFragment) fm.findFragmentById(R.id.map_framelayout);
if (mMapFragment == null) {
mMapFragment = new MyMapFragment();
mMapFragment.setRetainInstance(true);
mMapFragment.setMapCallback(this);
fm.beginTransaction().replace(R.id.map_framelayout, mMapFragment,"mapfrag").commit();
}
createMapIfNeeded();
return v;
}
@Override
public void onMapReady(GoogleMap map) {
createMapIfNeeded();
}
private void createMapIfNeeded(){
if(mLocManager == null){
mLocManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
mLocManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES,
this);
}
//locmanager can return null if no last known locaiton is available.
location = mLocManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
//if a map has not already been instantiated it'll return null
if(mMap == null){
//instantiate map
mMap = mMapFragment.getMap();
//check it has been instantiated
if(mMap != null){
mMap.setOnMapLongClickListener(this);
mMap.setOnInfoWindowClickListener(this);
mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
mMap.setMyLocationEnabled(true);
//Manipulate map here (add coordinates/polylines from trip etc etc.)
UiSettings setting = mMap.getUiSettings();
setting.setTiltGesturesEnabled(true);
setting.setRotateGesturesEnabled(true);
setting.setZoomControlsEnabled(true);
setting.setMyLocationButtonEnabled(true);
if(location != null){
CameraUpdate cu = CameraUpdateFactory.newLatLngZoom(new LatLng(location.getLatitude(), location.getLongitude()), 15);
mMap.animateCamera(cu);
}
}
}
}
现在MyMapFragment.java
public class MyMapFragment extends MapFragment{
private MapCallback callback;
public static interface MapCallback
{
public void onMapReady(GoogleMap map);
}
public void setMapCallback(MapCallback callback)
{
this.callback = callback;
}
@Override public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
if(callback != null) callback.onMapReady(getMap());
}
}
CHEERS !!!
答案 1 :(得分：0)
我希望这对你有用： https://github.com/jfeinstein10/SlidingMenu https://play.google.com/store/apps/details?id=com.slidingmenu.example&hl=en
答案 2 :(得分：-1)
在邮件线程上找到此问题的简便解决方法。这解决了我的问题。 使用相对布局并将此透明视图直接放在上面 你的地图片段。示例：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
class="com.google.android.gms.maps.SupportMapFragment"/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/transparent" />
</RelativeLayout>