如何在 Retrofit 2.0 响应中处理 JSON 空对象？答案

【问题标题】：How to proceed JSON empty object in Retrofit 2.0 response?如何在 Retrofit 2.0 响应中处理 JSON 空对象？
【发布时间】：2016-04-20 10:08:48
【问题描述】：

这里是一个json响应的例子。如您所见，新闻、number_likes、number_comment、number_post、user、owner 等字段始终存在。但是诸如：地点、地点标记、评论、相册、照片之类的字段并不总是存在。这取决于新闻的类型。

{
"result": true,
"news_list": [
{
"news": {
"id": "67",
"text": "",
"text_post": "",
"date_create": "1460321713"
},
"number_likes": "0",
"number_comment": "0",
"number_post": "0",
"user": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/08382.jpeg",
"last_activity": "1460035798"
},
"owner": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/08382.jpeg",
"last_activity": "1460035798"
},
"place": {
"id": "1",
"name": "test",
"avatar": ""
},
"place_mark": {
"id": "1",
"date_create": "1460321699"
}
},
{
"news": {
"id": "66",
"text": "",
"text_post": "",
"date_create": "1460321623"
},
"number_likes": "0",
"number_comment": "0",
"number_post": "0",
"user": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/08382.jpeg",
"last_activity": "1460035798"
},
"owner": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/08082.jpeg",
"last_activity": "1460035798"
},
"place": {
"id": "1",
"name": "test",
"avatar": ""
},
"comment": {
"id": "1",
"parent_id": "",
"text": "qwer",
"rating": "0",
"date_create": "1460321472"
},
"photos": []
},
{
"news": {
"id": "65",
"text": "new news",
"text_post": "",
"date_create": "1460320767"
},
"number_likes": "0",
"number_comment": "0",
"number_post": "0",
"user": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/08082.jpeg",
"last_activity": "1460035798"
},
"owner": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/0882.jpeg",
"last_activity": "1460035798"
},
"photos": [
{
"photo": {
"id": "84",
"name": "",
"filename": "2d20f883cb023a1ff14f32d0ee79a02c.jpeg",
"mime_type": "image/jpeg",
"height": "540",
"width": "442",
"link": "http://base_url/userPhotos/41/album/original/29a02c.jpeg"
}
},
{
"photo": {
"id": "85",
"name": "",
"filename": "2d20f883cb023a1ff14f32d0ee79a02c.jpeg",
"mime_type": "image/jpeg",
"height": "540",
"width": "442",
"link": "http://base_url/userPhotos/41/album/original/2d20f2c.jpeg"
}
}
]
},
{
"news": {
"id": "64",
"text": "",
"text_post": "",
"date_create": "1460320759"
},
"number_likes": "0",
"number_comment": "0",
"number_post": "0",
"user": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/0809fb.jpeg",
"last_activity": "1460035798"
},
"owner": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/0882.jpeg",
"last_activity": "1460035798"
},
"album": {
"id": "34",
"name": "asdfgh",
"description": "",
"position": ""
},
"photo": ""
}
]
}

这是我的响应模型：

public class GetNewsResponse {

private String result;

private List<NewsList> news_list;

private Errors errors;

public String getResult() {
    return result;
}

public List<NewsList> getNews_list() {
    return news_list;
}

public Errors getErrors() {
    return errors;
}


public class NewsList {

    private String number_likes;

    private String number_comment;

    private String number_post;

    private News news;

    private User user;

    private Owner owner;

    private Place place;

    private PlaceMark place_mark;

    private Comment comment;

    private Album album;

    private List<Photo2> photos;

    public String getNumber_likes() {
        return number_likes;
    }

    public String getNumber_comment() {
        return number_comment;
    }

    public String getNumber_post() {
        return number_post;
    }

    public News getNews() {
        return news;
    }

    public User getUser() {
        return user;
    }

    public Owner getOwner() {
        return owner;
    }

    public Place getPlace() {
        return place;
    }

    public PlaceMark getPlaceMark() {
        return place_mark;
    }

    public Comment getComment() {
        return comment;
    }

    public Album getAlbum() {
        return album;
    }

    public List<Photo2> getPhotos() {
            return photos;
    }
}


public class News {

    private String id;

    private String text;

    private String text_post;

    private String date_create;

    public String getId() {
        return id;
    }

    public String getText() {
        return text;
    }

    public String getDate_create() {
        return date_create;
    }

    public String getText_post() {
        return text_post;
    }
}

public class User {

    private String id;

    private String name;

    private String last_name;

    private String avatar;

    private String last_activity;

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getLast_name() {
        return last_name;
    }

    public String getAvatar() {
        return avatar;
    }

    public String getLast_activity() {
        return last_activity;
    }

}

public class Owner {

    private String id;

    private String name;

    private String last_name;

    private String avatar;

    private String last_activity;

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getLast_name() {
        return last_name;
    }

    public String getAvatar() {
        return avatar;
    }

    public String getLast_activity() {
        return last_activity;
    }
}

public class Place {

    private String id;

    private String name;

    private String avatar;

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getAvatar() {
        return avatar;
    }
}

public class PlaceMark {

    private String id;

    private String date_create;

    public String getId() {
        return id;
    }

    public String getDate_create() {
        return date_create;
    }
}

public class Comment {

    private String id;

    private String parent_id;

    private String text;

    private String rating;

    private String date_create;

    public String getId() {
        return id;
    }

    public String getParent_id() {
        return parent_id;
    }

    public String getRating() {
        return rating;
    }

    public String getText() {
        return text;
    }

    public String getDate_create() {
        return date_create;
    }
}

public class Album {

    private String id;

    private String name;

    private String description;

    private String position;

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getDescription() {
        return description;
    }

    public String getPosition() {
        return position;
    }

}

public class Photo2 {

    private Object photo;

    public Object getPhoto() {
        return photo;
    }
}

public class Photo {

    private String id;

    private String name;

    private String filename;

    private String mime_type;

    private String height;

    private String width;

    private String link;

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getFilename() {
        return filename;
    }

    public String getMime_type() {
        return mime_type;
    }

    public String getHeight() {
        return height;
    }

    public String getWidth() {
        return width;
    }

    public String getLink() {
        return link;
    }
}

public class Errors {

    private String text;

    public String getText() {
        return text;
    }

}
}

这是我的api方法实现：

public void getNewsMethod() {
sm.getNews(user_id, limit, offset, photo_size, avatar_size, all, new Callback(){

        @Override
        public void onResponse(Call<GetNewsResponse> call, Response<GetNewsResponse> response) {
            List<GetNewsResponse.NewsList> list = response.body().getNews_list();
            instantiateAdapter(list);
        }

        @Override
        public void onFailure(Call<GetNewsResponse> call, Throwable t) {
            Toast.makeText(MyNewsActivity.this, "get news failure", Toast.LENGTH_SHORT).show();
        }
    });
}

我使用改造 2.0.1 和原生 GSonConverterFactory：

private static Retrofit.Builder builder = new Retrofit.Builder()
.baseUrl(API_BASE_URL)
.addConverterFactory(GsonConverterFactory.create());

当照片 json 数组为空时，这是我在 json 反序列化时的错误：

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: 预期 BEGIN_OBJECT 但在第 1 行第 9480 列路径 $.news_list[11].photos[0].photo

请帮帮我！为了正确的 json 反序列化，我需要做什么？也许有人有编写自定义转换器工厂的经验，或者可以根据我的问题给我任何建议？谢谢。

【问题讨论】：

标签： android json gson retrofit2

【解决方案1】：

在您的 json 响应中寻找战利品。最后一个 NewsList 对象有问题。

{
"news": {
"id": "64",
"text": "",
"text_post": "",
"date_create": "1460320759"
},
"number_likes": "0",
"number_comment": "0",
"number_post": "0",
"user": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/0809fb.jpeg",
"last_activity": "1460035798"
},
"owner": {
"id": "41",
"name": "Jimmy",
"last_name": "",
"avatar": "http://base_url/userPhotos/41/album/original/0882.jpeg",
"last_activity": "1460035798"
},
"album": {
"id": "34",
"name": "asdfgh",
"description": "",
"position": ""
},
"photo": "" // <- the problem
}

您应该会收到一份根据您的规格要求的照片列表。但是你收到了一张带有字符串的标签照片。请检查您的网络服务。

【讨论】：