Question

我想将一个对象传递给一个包。现在我用GSON转换为Json对象。

bundle被传递，bundle有正确的字符串表示，但是当我从字符串创建对象时，我收到了一个巨大的错误。

FATAL EXCEPTION: main
    java.lang.RuntimeException: Failed to invoke private android.net.Uri() with no args
            at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:107)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:162)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
            at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
            at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
            at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
            at com.google.gson.Gson.fromJson(Gson.java:803)
            at com.google.gson.Gson.fromJson(Gson.java:768)
            at com.google.gson.Gson.fromJson(Gson.java:717)
            at com.google.gson.Gson.fromJson(Gson.java:689)
            at com.test.fragment.QFragment.onCreateView(QFragment.java:54)
            at android.app.Fragment.performCreateView(Fragment.java:1788)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:899)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1101)
            at android.app.BackStackRecord.run(BackStackRecord.java:688)
            at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1559)
            at android.app.FragmentManagerImpl$1.run(FragmentManager.java:445)
            at android.os.Handler.handleCallback(Handler.java:730)
            at android.os.Handler.dispatchMessage(Handler.java:92)
            at android.os.Looper.loop(Looper.java:158)
            at android.app.ActivityThread.main(ActivityThread.java:5789)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:843)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.InstantiationException: can't instantiate class android.net.Uri
            at java.lang.reflect.Constructor.constructNative(Native Method)
            at java.lang.reflect.Constructor.newInstance(Constructor.java:417)
            at com.google.gson.internal.ConstructorConstructor$3.construct(ConstructorConstructor.java:104)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:162)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
            at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
            at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
            at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
            at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
            at com.google.gson.Gson.fromJson(Gson.java:803)
            at com.google.gson.Gson.fromJson(Gson.java:768)
            at com.google.gson.Gson.fromJson(Gson.java:717)
            at com.google.gson.Gson.fromJson(Gson.java:689)
            at com.test.fragment.QFragment.onCreateView(QFragment.java:54)
            at android.app.Fragment.performCreateView(Fragment.java:1788)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:899)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1101)
            at android.app.BackStackRecord.run(BackStackRecord.java:688)
            at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1559)
            at android.app.FragmentManagerImpl$1.run(FragmentManager.java:445)
            at android.os.Handler.handleCallback(Handler.java:730)
            at android.os.Handler.dispatchMessage(Handler.java:92)
            at android.os.Looper.loop(Looper.java:158)
            at android.app.ActivityThread.main(ActivityThread.java:5789)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:843)
            at dalvik.system.NativeStart.main(Native Method)

我正在进行这样的转换：

public static QFragment newInstance(FModel oModel) {
    QFragment fragment = new QFragment();
    fragment.mOModel = oModel;
    Bundle bdl = new Bundle();
    bdl.putString("oModel", new Gson().toJson(oModel));
    fragment.setArguments(bdl);
    return fragment;
}

和我在createView上的片段：

 String jsonMyObject = null;
        Bundle args = this.getArguments();
        if (args != null) {
            jsonMyObject = args.getString("oModel");
        }
        mOrderModel = new Gson().fromJson(jsonMyObject, FModel.class);

解决此问题的最佳方法是什么？我是否需要更改为可序列化或可分割？

Answer 1

在FModel中发现问题的确有一个Uri。

写下来解决这个问题：

public class UriSerializer implements JsonSerializer<Uri> {
    public JsonElement serialize(Uri src, Type typeOfSrc, JsonSerializationContext context) {
        return new JsonPrimitive(src.toString());
    }
}

public class UriDeserializer implements JsonDeserializer<Uri> {
    @Override
    public Uri deserialize(final JsonElement src, final Type srcType,
                           final JsonDeserializationContext context) throws JsonParseException {
        return Uri.parse(src.getAsString());
    }
}

并按照以下方式进行Gson转换：

Gson gson = new GsonBuilder()
                .registerTypeAdapter(Uri.class, new UriSerializer())
                .create();
        bdl.putString("oModel",gson.toJson(oModel));

并在oncreate中重建：

Gson gson = new GsonBuilder()
                    .registerTypeAdapter(Uri.class, new UriDeserializer())
                    .create();
            jsonMyObject = args.getString("oModel");
            mOrderModel = gson.fromJson(jsonMyObject, FModel.class);

Answer 2

仅供参考，您可以通过将两个接口实现组合到一个类中来同时使用序列化和反序列化。

public class UriInOut implements JsonSerializer<Uri>, JsonDeserializer<Uri> {
  @Override
  public JsonElement serialize(Uri src, Type typeOfSrc, JsonSerializationContext context) {
    return new JsonPrimitive(src.toString());
  }

  @Override
  public Uri deserialize(final JsonElement src, final Type srcType,
                         final JsonDeserializationContext context) throws JsonParseException {
    return Uri.parse(src.getAsString());
  }
}
....
new GsonBuilder()   
    .registerTypeAdapter(Uri.class, new UriInOut())
    .create();

Answer 3

您也可以使用more efficient

的TypeAdapter

public final class UriAdapter extends TypeAdapter<Uri> {
  @Override 
  public void write(JsonWriter out, Uri uri) throws IOException {
    out.value(uri.toString());
  }

  @Override 
  public Uri read(JsonReader in) throws IOException {
    return Uri.parse(in.nextString());
  }
}

从Gson字符串创建对象不起作用

3 个答案: