一個json參數包含數組或對象中的數據。如何檢查數據是使用GSON的數組或對象

Question

我有無法更改的Web服務。所以我有一個參數叫內容。該參數包含數組或對象的數據。我的意思是有時候我以數組格式獲取數據，有時候我以對象格式獲取數據。

我正在使用gson庫（https://github.com/google/gson）來解析json。我創建了一個自定義類，並在此使用該參數。

class { 

@SerializedName("content") 
    private List<Content> content; 

    public List<Content> getContent() { 
     return content; 
    } 

    public void setContent(List<Content> content) { 
     this.content = content; 
    } 

所以當我在數組中獲取數據。沒關係。但它正在爲對象而崩潰。

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 409 path $.response.content 

更新：

當PARAM 內容是陣列則解析正確的。但是當內容參數是字符串。我收到錯誤。

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 410 path $.response.content 

我使用了TypeAdapterFactory。

public class ArrayAdapterFactory implements TypeAdapterFactory { 

    @Override 
    @SuppressWarnings("unchecked") 
    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) { 

     if (type.getRawType()!= Templetegt4StoryResponse.Response.Content.class) return null; 

     TypeAdapter<Templetegt4StoryResponse.Response.Content> defaultAdapter = (TypeAdapter<Templetegt4StoryResponse.Response.Content>) gson.getDelegateAdapter(this, type); 

     TypeAdapter<T> typeAdapter = (TypeAdapter<T>) new AddressAdapter(defaultAdapter); 
     return typeAdapter; 

     //return (TypeAdapter<T>) new AddressAdapter(defaultAdapter); 
    } 

} 


public class AddressAdapter extends TypeAdapter<Templetegt4StoryResponse.Response.Content> { 

    protected TypeAdapter<Templetegt4StoryResponse.Response.Content> defaultAdapter; 

    /** 
    * @param defaultAdapter 
    */ 
    public AddressAdapter(TypeAdapter<Templetegt4StoryResponse.Response.Content> defaultAdapter) { 
     this.defaultAdapter = defaultAdapter; 
    } 

    /** 
    * {@inheritDoc} 
    */ 
    @Override 
    public void write(JsonWriter out, Templetegt4StoryResponse.Response.Content value) throws IOException { 
     defaultAdapter.write(out, value); 
    } 

    /** 
    * {@inheritDoc} 
    */ 
    @Override 
    public Templetegt4StoryResponse.Response.Content read(JsonReader in) throws IOException { 
     System.out.println("in.peek = "+in.peek()); 

     if (in.peek()==JsonToken.STRING) { 
      in.skipValue(); 
      return null; 
     } 
     System.out.println("in.peek = "+in.peek()); 

     return defaultAdapter.read(in); 
    } 

}

我叫它

Gson gson = new GsonBuilder().registerTypeAdapterFactory(new ArrayAdapterFactory()).create(); 
return gson.fromJson(str, Templetegt4StoryResponse.class); 


public class Templetegt4StoryResponse { 

    @SerializedName("content") 
    private List<Content> content; 


    public class Content{ 

     @SerializedName("sequence_no") 
     private String sequence_no; 

     @SerializedName("is_url_code") 
     private String is_url_code; 
} 

}

這是JSON。內容參數可以採用兩種格式。

content: [ 
{ 
sequence_no: "1", 
is_url_code: "is_url", 
} 
] 


content: "this is new text", 

Answer 1

在GSON你可以使用自定義序列，

創建自定義TypeAdapter這樣，

class ArrayAdapter<T> extends TypeAdapter<List<T>> { 

    private Class<T> adapterclass; 

    public ArrayAdapter(Class<T> adapterclass) { 
     this.adapterclass = adapterclass; 
    } 

    @Override 
    public List<T> read(JsonReader reader) throws IOException { 

     List<T> list = new ArrayList<T>(); 
     Gson gson = new GsonBuilder().registerTypeAdapterFactory(new ArrayAdapterFactory()).create(); 

     final JsonToken token = reader.peek(); 
     // Handling of Scenario 2(Check JavaDoc for the class) : 
     if (token == JsonToken.STRING || token == JsonToken.NUMBER || 
       token == JsonToken.BOOLEAN) { 
      T inning = (T) gson.fromJson(reader, adapterclass); 
      list.add(inning); 
     } else if (token == JsonToken.BEGIN_OBJECT) { 
      // Handling of Scenario 1(Check JavaDoc for the class) : 
      T inning = (T) gson.fromJson(reader, adapterclass); 
      list.add(inning); 
     } else if (token == JsonToken.BEGIN_ARRAY) { 
      reader.beginArray(); 
      while (reader.hasNext()) { 
       @SuppressWarnings("unchecked") 
       T inning = (T) gson.fromJson(reader, adapterclass); 
       list.add(inning); 
      } 
      reader.endArray(); 
     } 

     return list; 
    } 

    @Override 
    public void write(JsonWriter writer, List<T> value) throws IOException { 

    } 


} 

，創造這樣typeAdapter工廠，

public class ArrayAdapterFactory implements TypeAdapterFactory { 

    @Override 
    @SuppressWarnings({"unchecked", "rawtypes"}) 
    public <T> TypeAdapter<T> create(final Gson gson, final TypeToken<T> type) { 

     TypeAdapter<T> typeAdapter = null; 
     try { 
      if (type.getRawType() == ArrayList.class) { 

       typeAdapter = new ArrayAdapter((Class) ((ParameterizedType) type.getType()).getActualTypeArguments()[0]); 
      } 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

     return typeAdapter; 

    } 

} 

經過此登記呃這個工廠與你的gson對象，

Gson gson = new GsonBuilder().registerTypeAdapterFactory(new ArrayAdapterFactory()).create(); 

Answer 2

if (json instanceof JSONObject) 
    //you have an object 
else if (json instanceof JSONArray) 
    //you have an array