谷歌地图代码中的BadParcelableException

Question

运行稍微修改过的Google Maps示例会在Google Maps代码中抛出BadParcelableException。LatLng类是可打包的，但找不到。似乎Google Maps代码正在试图解包未被其打包的对象。问题出在什么情况下？

package com.example.mapdemo;

import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapView;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

import android.os.Bundle;

public class RawMapViewDemoActivity extends android.support.v4.app.FragmentActivity {
    private MapView mMapView;

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

        mMapView = (MapView) findViewById(R.id.map);
        mMapView.onCreate(savedInstanceState);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        mMapView.onSaveInstanceState(outState);

        outState.putParcelable("marker", new LatLng(0, 0));
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);

        LatLng ll = savedInstanceState.getParcelable("marker");
    }
}

..。

FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity 
    ComponentInfo{com.example.mapdemo/com.example.mapdemo.RawMapViewDemoActivity}: 
    android.os.BadParcelableException: ClassNotFoundException when unmarshalling: 
    com.google.android.gms.maps.model.LatLng
   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
   at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:2832)
   at android.app.ActivityThread.access$1600(ActivityThread.java:117)
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
   at android.os.Handler.dispatchMessage(Handler.java:99)
   at android.os.Looper.loop(Looper.java:130)
   at android.app.ActivityThread.main(ActivityThread.java:3683)
   at java.lang.reflect.Method.invokeNative(Native Method)
   at java.lang.reflect.Method.invoke(Method.java:507)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
   at dalvik.system.NativeStart.main(Native Method)

Caused by: android.os.BadParcelableException: 
ClassNotFoundException when unmarshalling: com.google.android.gms.maps.model.LatLng
   at android.os.Parcel.readParcelable(Parcel.java:1958)
   at android.os.Parcel.readValue(Parcel.java:1846)
   at android.os.Parcel.readMapInternal(Parcel.java:2083)
   at android.os.Bundle.unparcel(Bundle.java:208)
   at android.os.Bundle.getBundle(Bundle.java:1078)
   at com.google.android.gms.maps.internal.MapStateHelper
       .getParcelableFromMapStateBundle(MapStateHelper.java:41)
   at maps.y.ae.a(Unknown Source)
   at maps.y.bm.onCreate(Unknown Source)
   at com.google.android.gms.maps.internal.IMapViewDelegate$Stub
       .onTransact(IMapViewDelegate.java:66)
   at android.os.Binder.transact(Binder.java:279)
   at com.google.android.gms.maps.internal.IMapViewDelegate$a$a
       .onCreate(Unknown Source)
   at com.google.android.gms.maps.MapView$b.onCreate(Unknown Source)
   at com.google.android.gms.internal.c$3.a(Unknown Source)
   at com.google.android.gms.internal.i.b(Unknown Source)
   at com.google.android.gms.maps.MapView$a.a(Unknown Source)
   at com.google.android.gms.maps.MapView$a.a(Unknown Source)
   at com.google.android.gms.internal.c.a(Unknown Source)
   at com.google.android.gms.internal.c.onCreate(Unknown Source)
   at com.google.android.gms.maps.MapView.onCreate(Unknown Source)
   at com.example.mapdemo.RawMapViewDemoActivity
       .onCreate(RawMapViewDemoActivity.java:40)
   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
   ... 12 more

Answer 1

为了补充这里的现有答案，在调用mapView.onCreate之前，我已经从保存状态中删除了我的包裹，它工作得很好。

但是，在将ViewPager添加到我的片段后，我没有意识到BadParcelableException已经返回，并且代码已经投入生产。事实证明，ViewPager也保存了它的状态，并且因为它是Support Library的一部分，所以Google Map无法找到要对其进行解包的类。

所以我选择颠倒这个过程，而不是从我知道的Bundle中删除包裹，我选择为地图创建一个新的Bundle，只复制地图的状态。

private final static String BUNDLE_KEY_MAP_STATE = "mapData";

@Override
public void onSaveInstanceState(Bundle outState) {
    // Save the map state to it's own bundle
    Bundle mapState = new Bundle();
    mapView.onSaveInstanceState(mapState);
    // Put the map bundle in the main outState
    outState.putBundle(BUNDLE_KEY_MAP_STATE, mapState);
    super.onSaveInstanceState(outState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_map, container, false);
    mapView = (MapView) view.findViewById(R.id.mapView);
    mapView.getMapAsync(this);

    Bundle mapState = null;
    if (savedInstanceState != null) {
        // Load the map state bundle from the main savedInstanceState
        mapState = savedInstanceState.getBundle(BUNDLE_KEY_MAP_STATE);
    }

    mapView.onCreate(mapState);
    return view;
}

Answer 2

我尝试了前面的两个答案，但没有成功，但我找到了另一个解决方法：

保存状态时，在将数据添加到捆绑包之前，请注意转发MapView.onSaveInstanceState调用(您做得很好)：

@Override
public void onSaveInstanceState(Bundle outState) {

    // Forward the call BEFORE adding our LatLng array, else it will crash :
    _mapView.onSaveInstanceState(outState);

    // Put your Parcelable in the bundle:
    outState.putParcelableArray("myLatLng", new LatLng(0, 0) );
}

在恢复onCreate / onRestore中的状态时，检查捆绑包是否不为空，如果是，获取您的包裹，然后在转发调用之前将其从捆绑包中移除：

@Override
public void onCreate(Bundle savedInstanceState) {

    // If the bundle is not null, get your Parcelable :
    LatLng myLatLng = null;
    if(savedInstanceState != null) {

        myLatLng = (LatLng) savedInstanceState.getParcelable("myLatLng");

        // Remove your Parcelable from the bundle, else it will crash :
        savedInstanceState.remove("myLatLng");
    }

    // Forward the call :
    _mapView.onCreate(savedInstanceState);
    setUpMapIfNeeded();
}

Answer 3

此问题已在code.google.com here上归档，以防您想要启动它。

同时，我已经设法绕过了这个问题，只需将我的Parcelable添加到捆绑包中，然后再将其添加到最终的onSaveInstanceState捆绑包中。这是因为捆绑包是MapView的内部ClassLoader已知的类。

我创建了两个非常小的util方法来为我做这件事。下面是代码

public static Parcelable unbundleParcelable(String key, Bundle src) {
    Bundle b = src.getBundle(key);
    if (b != null) {
        return b.getParcelable("bundle_parcelable_util_key");
    }
    return null;
}

public static void bundleParcelable(String key, Bundle dest, Parcelable parcelable) {
    Bundle b = new Bundle();
    b.putParcelable("bundle_parcelable_util_key", parcelable);
    dest.putBundle(key, b);
}

我已经修改了前一篇文章中的代码，以使用我的临时解决方案。下面是我如何使用它。

@Override
public void onSaveInstanceState(Bundle outState) {

    // Forward the call BEFORE adding our LatLng array, else it will crash :
    _mapView.onSaveInstanceState(outState);

    // Put your Parcelable in the bundle:
    bundleParcelable("myLatLng", outState, new LatLng(0, 0));
}

@Override
public void onCreate(Bundle savedInstanceState) {
    // Forward the call :
    _mapView.onCreate(savedInstanceState);

    LatLng myLatLng = null;
    if(savedInstanceState != null) {
        // Extract your Parcelable
        myLatLng = (LatLng) unbundleParcelable("myLatLng", savedInstanceState);
    }

    setUpMapIfNeeded();
}

这应该适用于您在项目中使用的任何自定义Parcelable。