java – 如何使用GSON反序列化不同对象的数组

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我收到这样的JSON

[
  {
    "albums" : [
      {"id":"0", "name":"name"},
      {"id":"1", "name":"name"}
    ],
    "name":"name"
  },
  {
    "tracks" : [
      {"id":"0", "name":"name", "duration":"3:30"},
      {"id":"1", "name":"name", "duration":"2:40"}
    ],
    "name":"name"
  },
  {
    "playlists" : [
      {"id":"0", "name":"name", "tracksCount":"3"},
      {"id":"1", "name":"name", "tracksCount":"40"}
    ],
    "name":"name"
  }
]

当然,我实现了包含所有字段和类的Track,Album和Playlist类

Tracks {
  String name;
  List<Track> tracks;
}
Albums {
  String name;
  List<Album> albums;
}
Playlists {
  String name;
  List<Playlist> playlists;
}

我试图用以下方法对其进行反序列化：

Gson gson = new Gson();
JsonResponse[] rez = gson.fromJson(str, JsonResponse[].class);

JsonResponse在哪里

class JsonResponse {
  Albums albums;
  Tracks tracks;
  Playlists playlists;
}

但我得到错误：

11-20 19:24:55.210: E/AndroidRuntime(5432): FATAL EXCEPTION: main
11-20 19:24:55.210: E/AndroidRuntime(5432):
com.google.gson.JsonSyntaxException: java.lang.IllegalStateException:
Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 13 11-20
19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:176)
11-20 19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:93)
11-20 19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:172)
11-20 19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
11-20 19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.internal.bind.ArrayTypeAdapter.read(ArrayTypeAdapter.java:72)
11-20 19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.Gson.fromJson(Gson.java:803) 11-20 19:24:55.210:
E/AndroidRuntime(5432): at
com.google.gson.Gson.fromJson(Gson.java:768) 11-20 19:24:55.210:
E/AndroidRuntime(5432): at
com.google.gson.Gson.fromJson(Gson.java:717) 11-20 19:24:55.210:
E/AndroidRuntime(5432): at
com.google.gson.Gson.fromJson(Gson.java:689) 11-20 19:24:55.210:
11-20 19:24:55.210: E/AndroidRuntime(5432): at
android.os.ResultReceiver$MyRunnable.run(ResultReceiver.java:43) 11-20
19:24:55.210: E/AndroidRuntime(5432): at
android.os.Handler.handleCallback(Handler.java:587) 11-20
19:24:55.210: E/AndroidRuntime(5432): at
android.os.Handler.dispatchMessage(Handler.java:92) 11-20
19:24:55.210: E/AndroidRuntime(5432): at
android.os.Looper.loop(Looper.java:130) 11-20 19:24:55.210:
E/AndroidRuntime(5432): at
android.app.ActivityThread.main(ActivityThread.java:3687) 11-20
19:24:55.210: E/AndroidRuntime(5432): at
java.lang.reflect.Method.invokeNative(Native Method) 11-20
19:24:55.210: E/AndroidRuntime(5432): at
java.lang.reflect.Method.invoke(Method.java:507) 11-20 19:24:55.210:
E/AndroidRuntime(5432): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
11-20 19:24:55.210: E/AndroidRuntime(5432): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 11-20
19:24:55.210: E/AndroidRuntime(5432): at
dalvik.system.NativeStart.main(Native Method) 11-20 19:24:55.210:
E/AndroidRuntime(5432): Caused by: java.lang.IllegalStateException:
Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 13 11-20
19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.stream.JsonReader.beginObject(JsonReader.java:374)
11-20 19:24:55.210: E/AndroidRuntime(5432): at
com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:165)
11-20 19:24:55.210: E/AndroidRuntime(5432): … 21 more

附： json响应中的某些项可能会被遗漏.例如

[
  {
    "albums" : [
      {"id":"0", "name":"name"},
      {"id":"1", "name":"name"}
    ],
    "name":"name"
  }
 ]

那么问题是什么？如何反序列化这个JSON？

顺便说一句,我不能改变JSON.所以我需要一个解析它的代码.

解决方法:

这样做

你的数据

    String json = "[{\"albums\":[{\"id\":\"0\",\"name\":\"name\"},{\"id\":\"1\",\"name\":\"name\"}],\"name\":\"name\"},{\"tracks\":[{\"id\":\"0\",\"name\":\"name\",\"duration\":\"3:30\"},{\"id\":\"1\",\"name\":\"name\",\"duration\":\"2:40\"}],\"name\":\"name\"},{\"playlists\":[{\"id\":\"0\",\"name\":\"name\",\"tracksCount\":\"3\"},{\"id\":\"1\",\"name\":\"name\",\"tracksCount\":\"40\"}],\"name\":\"name\"}]";

你的pojos

class JsonResponse {
      ArrayList<Album> albums;
      ArrayList<Track> tracks;
      ArrayList<Playlist> playlists;
      String name;
    @Override
    public String toString() {
        return "JsonResponse [albums=" + albums + ", tracks=" + tracks
                + ", playlists=" + playlists + ", name=" + name + "]";
    }     
}



class Track{
    int id;
    String name;
    String duration;
    @Override
    public String toString() {
        return "Track [id=" + id + ", name=" + name + ", duration=" + duration
                + "]";
    }    
}

class Album{
    int id;
    String name;
    @Override
    public String toString() {
        return "Album [id=" + id + ", name=" + name + "]";
    }   
}

class Playlist{ 
    int id;
    String name;
    int tracksCount;
    @Override
    public String toString() {
        return "Playlist [id=" + id + ", name=" + name + ", tracksCount="
                + tracksCount + "]";
    }

}

这里是反序列化的数组.

   JsonParser parser = new JsonParser();
   JsonArray Jarray = parser.parse(json).getAsJsonArray();
   Gson gson = new Gson();
   for(JsonElement obj : Jarray )
   {
        JsonResponse jsonResponse = gson.fromJson( obj , JsonResponse.class);
        System.out.println(jsonResponse);
   }

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