• 写AdapterFactory类，实现TypeAdapterFactory接口

public class BaseJsonDataEmptyStringAdapterFactory implements TypeAdapterFactory {

    @Override
    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {

        Class<? super T> rawType = typeToken.getRawType();
        TypeAdapter<T> originAdapter = gson.getAdapter(typeToken);

        //如果是String类型，则直接用原来的Adapter转换
        return String.class.equals(rawType) ? originAdapter : new Adapter(gson,originAdapter, rawType);
    }

    private class Adapter<E> extends TypeAdapter<E> {

        private final Gson context;
        private final Class<E> componentType;
        private final TypeAdapter<E> componentTypeAdapter;

        public Adapter(Gson context, TypeAdapter<E> componentTypeAdapter, Class<E> componentType) {
            this.context = context;
            this.componentTypeAdapter =componentTypeAdapter;
            this.componentType = componentType;
        }

        @Override
        public void write(JsonWriter out, E value) throws IOException {
            if(componentTypeAdapter != null) {
                componentTypeAdapter.write(out, value);
            }
        }

        @Override
        public E read(final JsonReader in) throws IOException {

            //如果下一个为JsonToken.STRING的起点，说明是下个节点是字符串
            if (in.peek() == JsonToken.STRING) {
                in.skipValue();
                return null;
            }
            if(componentTypeAdapter != null) {
                return componentTypeAdapter.read(in);
            }
            return null;
        }
    }
}

• 在有错误的字段加上@JsonAdapter即可

public class BaseJson<T> implements Serializable{

    @JsonAdapter(BaseJsonDataEmptyStringAdapterFactory.class)
    private T data;
    private String code;
    private String error;
    private String message;
    ...
}