如何反序列化可能是字符串，对象或列表的json / gson

我有以下json

"notes": {"note": [ { "content": "Having wisdom teeth removed.", "from": "employee" }, { "content": "Get well soon", "from": "manager" } ]}, 

问题在于价值也是如此

  "notes": "", 

要么

 "notes": {"note": { "content": "This is a test note.", "from": "employee" }}, 

并将其存储在这些中

 public class Notes { @SerializedName ("note") public List note; } public class Note { @SerializedName ("content") public String content; @SerializedName ("from") public String from; } 

我相信我解决了不是数组而是通过这样做成为单个对象的问题

 public class Json { private static Gson gson; private static class MyNoteClassTypeAdapter implements JsonDeserializer<List> { public List deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext ctx) { List vals = new ArrayList(); if (json.isJsonArray()) { for (JsonElement e : json.getAsJsonArray()) { vals.add((RequestsDTO.Note) ctx.deserialize(e, RequestsDTO.Note.class)); } } else if (json.isJsonObject()) { vals.add((RequestsDTO.Note) ctx.deserialize(json,RequestsDTO.Note.class)); } else { throw new RuntimeException("Unexpected JSON type: " + json.getClass()); } return vals; } } public static Gson getGson() { if (gson == null) { Type ListType = new TypeToken<List>() {}.getType(); GsonBuilder builder = new GsonBuilder(); builder.registerTypeAdapter(DateTime.class, new DateTimeSerializer()); builder.registerTypeAdapter(ListType, new MyNoteClassTypeAdapter()); gson = builder.create(); } return gson; } } 

现在，当整个事情刚刚回来时，我被困在了……

Answer 1

我的想法是尝试将"note"字段（来自"notes" JSONObject ）作为JSONArray ，如果它抛出exception将意味着没有"note" JSONArray进入"notes" JSONObject ，这意味着"note"是JSONObject 。 我们可以通过note字段为String来找出情况。

 try { //String jsonString="{\"notes\": {\"note\": [{\"content\": \"Having wisdom teeth removed.\",\"from\": \"employee\" }, {\"content\": \"Get well soon\", \"from\": \"manager\"} ] }}"; //String jsonString="{\"notes\": { \"note\": {\"content\": \"This is a test note.\",\"from\": \"employee\"}}}"; String jsonString="{\"notes\": { \"note\": \"\"}}"; JSONObject jsonObject=new JSONObject(jsonString); JSONObject jsonObjectNotes=jsonObject.getJSONObject("notes"); try{ JSONArray jsonArrayNote=jsonObjectNotes.getJSONArray("note"); for (int i = 0; i < jsonArrayNote.length(); i++) { JSONObject jsonObject2= jsonArrayNote.getJSONObject(i); String stringContent=jsonObject2.getString( "content"); String stringFrom= jsonObject2.getString( "from"); Log.e(getClass().getName(), "content="+stringContent +"; from="+stringFrom); } } catch(JSONException e){ //that means that jsonObjectNotes has no jsonArray with name "notes" and "notes" is jsonObject try{ JSONObject jsonObject3=jsonObjectNotes.getJSONObject("note"); String stringContent=(String) jsonObject3.get( "content"); String stringFrom=(String) jsonObject3.get( "from"); Log.e(getClass().getName(), "content="+stringContent +"; from="+stringFrom); } catch(JSONException ex){ //that means that jsonObjectNotes has no jsonObject with name "notes" and "notes" is empty String String stringNote=jsonObjectNotes.getString("note") ; Log.e(getClass().getName(), "note is string ="+ stringNote); } } } catch (JSONException e) { e.printStackTrace(); } 

在我的示例代码中，另一个get操作也可以抛出jsonExceptions但我认为你明白了。

Answer 2

看看Genson图书馆http://code.google.com/p/genson/ 。 如果您的类是内部类，则将它们设置为静态。 以下代码应该可以解决您的问题。

 Genson genson = new Genson.Builder().withDeserializerFactory(new NotesDeserializerFactory()).create(); Notes notes = genson.deserialize(in, Notes.class); // Define a factory so you can delegate the deserialization to existing mechanisms for lists and beans class NotesDeserializerFactory implements Factory> { @Override public Deserializer create(Type type, Genson genson) { Converter> noteListConverter = genson.provideConverter(new GenericType>() {}.getType()); Converter noteConverter = genson.provideConverter(Note.class); return new NotesDeserializer(noteListConverter, noteConverter); } } // define an implementation for you Notes class so you can handle the different cases class NotesDeserializer implements Deserializer { private final Converter> noteListConverter; private final Converter noteConverter; public NotesDeserializer(Converter> noteListConverter, Converter noteConverter) { this.noteListConverter = noteListConverter; this.noteConverter = noteConverter; } @Override public Notes deserialize(ObjectReader reader, Context ctx) throws TransformationException, IOException { Notes notes = new Notes(); if (reader.getValueType() == ValueType.ARRAY) notes.note = noteListConverter.deserialize(reader, ctx); else if (reader.getValueType() == ValueType.OBJECT) notes.note = Arrays.asList(noteConverter.deserialize(reader, ctx)); else { // it is a litteral (string, numeric, boolean, null) notes.note = new ArrayList(); } return notes; } } 

Answer 3

请参阅下面的代码片段，使用Gson库反序列化您的json，无exception。

 String jsonStr = "your json string "; Gson gson = new Gson(); JsonObject jsonObj = gson.fromJson (jsonStr, JsonElement.class).getAsJsonObject(); JsonElement elem = jsonObj.get("note"); if(elem.isJsonArray()) { //**Array** List notelist = gson.fromJson(elem.toString(), new TypeToken>(){}.getType()); } else if(elem.isJsonObject()) { //**Object** Note note = gson.fromJson(elem.toString(), Note.class); } else { //**String** String note = elem.toString(); }