{
 "code":0,
 "msg":"ok",
 "data":{
  "id":5638,
  "newsId":5638
 }
}

public class JsonBean {
 private int id;
 private int newsId;

 public int getId() {
  return id;
 }

 public void setId(int id) {
  this.id = id;
 }

 public int getNewsId() {
  return newsId;
 }

 public void setNewsId(int newsId) {
  this.newsId = newsId;
 }
}

{
 "code":0,
 "msg":"ok",
 "data":{
  "id":5638,
  "newsId":""
 }
}

public class IntegerDefault0Adapter implements JsonSerializer<Integer>, JsonDeserializer<Integer> {
 @Override
 public Integer deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
   throws JsonParseException {
  try {
   if (json.getAsString().equals("") || json.getAsString().equals("null")) {//定义为int类型,如果后台返回""或者null,则返回0
    return 0;
   }
  } catch (Exception ignore) {
  }
  try {
   return json.getAsInt();
  } catch (NumberFormatException e) {
   throw new JsonSyntaxException(e);
  }
 }

 @Override
 public JsonElement serialize(Integer src, Type typeOfSrc, JsonSerializationContext context) {
  return new JsonPrimitive(src);
 }
}

public class DoubleDefault0Adapter implements JsonSerializer<Double>, JsonDeserializer<Double> {
 @Override
 public Double deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
  try {
   if (json.getAsString().equals("") || json.getAsString().equals("null")) {//定义为double类型,如果后台返回""或者null,则返回0.00
    return 0.00;
  }
   } catch (Exception ignore) {
  }
  try {
   return json.getAsDouble();
  } catch (NumberFormatException e) {
   throw new JsonSyntaxException(e);
  }
 }

 @Override
 public JsonElement serialize(Double src, Type typeOfSrc, JsonSerializationContext context) {
  return new JsonPrimitive(src);
 }
}

public class LongDefault0Adapter implements JsonSerializer<Long>, JsonDeserializer<Long> {
 @Override
 public Long deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
  throws JsonParseException {
  try {
   if (json.getAsString().equals("") || json.getAsString().equals("null")) {//定义为long类型,如果后台返回""或者null,则返回0
     return 0l;
    }
   } catch (Exception ignore) {
  }
  try {
   return json.getAsLong();
  } catch (NumberFormatException e) {
   throw new JsonSyntaxException(e);
  }
 }

 @Override
 public JsonElement serialize(Long src, Type typeOfSrc, JsonSerializationContext context) {
  return new JsonPrimitive(src);
 }
}

return new Retrofit.Builder()
  .client(okHttpClient)//设置网络访问框架
  .addConverterFactory(GsonConverterFactory.create(buildGson()))//添加json转换框架
  .addCallAdapterFactory(RxJavaCallAdapterFactory.create())//让Retrofit支持RxJava
  .baseUrl(baseUrl)
  .build();

/**
 * 增加后台返回""和"null"的处理
 * 1.int=>0
 * 2.double=>0.00
 * 3.long=>0L
 *
 * @return
 */
public static Gson buildGson() {
 if (gson == null) {
  gson = new GsonBuilder()
    .registerTypeAdapter(Integer.class, new IntegerDefault0Adapter())
    .registerTypeAdapter(int.class, new IntegerDefault0Adapter())
    .registerTypeAdapter(Double.class, new DoubleDefault0Adapter())
    .registerTypeAdapter(double.class, new DoubleDefault0Adapter())
    .registerTypeAdapter(Long.class, new LongDefault0Adapter())
    .registerTypeAdapter(long.class, new LongDefault0Adapter())
    .create();
 }
 return gson;
}