我怎麼反序列化對象的不同陣列GSON

我收到JSON這樣我怎麼反序列化對象的不同陣列GSON

[ 
    { 
    "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" 
    } 
]

當然我實現類的曲目，專輯和播放列表包含了所有的領域和類

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

我「M試圖與反序列化它：

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

其中JsonResponse爲

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

但我得到的錯誤：

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響應中的某些項可能會丟失。例如

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

那麼，什麼是問題，我該如何反序列化這個JSON？

順便說一句我不能改變JSON。所以我需要一個解析它的代碼。

來源

2013-11-20 oleg.semen

我不能改變JSON。所以我需要一個解析它的代碼。 –

希望您擁有專輯，曲目和播放列表類，只需在JsonResponse中進行更改，除了JsonResonse類中的小錯誤外，您的方法是正確的。 –

謝謝大家的幫助！這是我的解決方案。

public class JsonResponse { 
    public static class Item { 
     String name; 
    } 

    public static class Tracks extends Item { 
     List<Track> tracks; 
    } 

    public static class Albums extends Item { 
     List<Album> albums; 
    } 

    public static class Playlists extends Item { 
     List<Playlist> playlists; 
    } 

    public static class JsonResponseDeserialize implements JsonDeserializer<List<? extends Item>> { 
     Gson gson = new Gson(); 
     @Override 
     public List<? extends Item> deserialize(JsonElement el, Type type, JsonDeserializationContext context) throws JsonParseException { 
      List<Item> ls = new ArrayList<Item>(); 
      JsonArray jarr = el.getAsJsonArray(); 
      for (JsonElement e : jarr) { 
       Item i; 
       if (e.getAsJsonObject().get("tracks") != null){ 
        i = gson.lsomJson(e, Tracks.class); 
        if (i != null) { 
         ls.add(i); 
         continue; 
        } 
       } 
       if (e.getAsJsonObject().get("albums") != null){ 
        i = gson.lsomJson(e, Albums.class); 
        if (i != null) { 
         ls.add(i); 
         continue; 
        } 
       } 
       if (e.getAsJsonObject().get("playlists") != null){ 
        i = gson.lsomJson(e, Playlists.class); 
        if (i != null) { 
         ls.add(i); 
         continue; 
        } 
       } 
      } 
      return ls; 
     } 
    } 

    private Tracks _tracks; 
    private Albums _albums; 
    private Playlists _playlists; 
}

反序列化：

private static List<? extends Item> getDatalsomJson(String jsonString) { 
    Type type = new TypeToken<List<? extends JsonResponse.Item>>(){}.getType(); 
    GsonBuilder gb = new GsonBuilder(); 
    gb.registerTypeAdapter(type, new JsonResponse.JsonResponseDeserialize()); 
    Gson gson = gb.create(); 
    List<? extends Item> ls = gson.lsomJson(jsonString, type); 
    return ls; 
}

來源

2013-11-21 12:35:44

lsomJson無法找到它 – Moorthy

您發佈的JSON不會顯示JSONResponse對象的數組，而是它包含類型爲Album，Tracks和Playlists的JSON對象。如果你有這個代替這將是不同的：

[ 
    { 
    { 
     "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" 
    } 
    } 
]

另外，如果你的對象最終是太複雜了，還記得你總是可以實現自己的JSONDeserializer類，並在GSONBuilder對象進行註冊調用創建權之前（）在上面。

來源

2013-11-20 17:33:40 Miquel

我無法更改JSON。所以我需要一個解析它的代碼。 –

我明白JSON結構不在你的控制之下，但是你誤解了你的東西：你沒有一個JSONResponse對象的數組，但是有一組播放列表，Track等等......所以沒問題，我只需要實現你自己的解串器;這裏是一個[示例]（http://stackoverflow.com/questions/6096940/how-do-i-write-a-custom-json-deserializer-for-gson） – Miquel

做這樣

你的數據

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POJO

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 + "]"; 
    } 

}

這裏反序列化的陣列。

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); 
    }

來源

2013-11-20 18:51:43 Prabhakaran

其實你在JsonResponse類中犯了錯誤。

其清晰的形式表明您的json格式，它從數組開始，而在JsonResponse類中，您只是編寫單個對象而不是對象集合。如果你仔細看看Gson的例外情況爲「BEGIN_OBJECT but was BEGIN_ARRAY」。這意味着Gason擁有專輯，曲目和播放列表，而不是專輯，曲目和播放列表類的對象。

只要你需要JsonResponse類變化不大如下

private List<Albums> albums; 
private List<Tracks> tracks; 
private List<Playlists> playlists;

來源

2013-11-20 19:42:30

JsonResponse類包含對象，但不列出/數組，因爲那裏是列表/數組旁邊的字符串字段「名稱」。它是類專輯的一個對象，其中包含列表專輯;和字符串名稱; –

每個列表包含它自己類型的對象，並且每個對象都有字符串字段名稱，因爲每個實例都有其自己的屬性 –

我怎麼反序列化對象的不同陣列GSON

回答

相關問題