[英]How do I parse nested objects with Retrofit 2?
我正在消費一個newsapi
它的JSON響應與此相似。
{
"status": "ok",
"articles": [
{
"source": {
"id": "bbc-news",
"name": "BBC News"
},
"author": "BBC News",
"title": "Jubilation greets end of Mugabe era",
"description": "Zimbabweans celebrate late into the night after Robert Mugabe resigns, ending 37-year rule.",
"url": "http://www.bbc.co.uk/news/world-africa-42072673",
"urlToImage": "https://ichef.bbci.co.uk/images/ic/1024x576/p05nt3bn.jpg",
"publishedAt": "2017-11-22T02:46:09Z"
},
{
"source": {
"id": "bbc-news",
"name": "BBC News"
},
"author": "BBC News",
"title": "Dramatic moment N Korea soldier defects",
"description": "He raced across the border on foot, closely pursued by North Korean troops who shot at him several times.",
"url": "http://www.bbc.co.uk/news/world-asia-42075986",
"urlToImage": "https://ichef.bbci.co.uk/news/1024/cpsprodpb/F519/production/_98854726_p05ntph4.jpg",
"publishedAt": "2017-11-22T04:45:14Z"
},
{
....
}
]
}
我正在嘗試將Retrofit 2與GSON配合使用。
我的POJO類是這些。
新聞列表.java
public class NewsList {
public Articles[] articles;
private String status;
@Override
public String toString() {
return "ClassPojo [articles = " + articles + ", status = " + status + "]";
}
// getters and setters
}
Articles.java
public class Articles {
private String publishedAt;
private String author;
private String urlToImage;
private String title;
private Source source;
private String description;
private String url;
// getters and setters
}
源代碼
public class Source {
private String id;
private String name;
// getters and setters
}
我的翻新客戶看起來像這樣;
public interface NewsroomAPI {
String BASE_URL = "https://newsapi.org/v2/";
@GET("top-headlines")
Call<NewsList> loadNews(@Query("sources") String source);
}
在我的MainActivity.java
我這樣調用Retrofit客戶端;
OkHttpClient okHttpClient = new OkHttpClient().newBuilder().addInterceptor(new Interceptor() {
@Override public okhttp3.Response intercept(Chain chain) throws IOException {
Request originalRequest = chain.request();
Request.Builder builder = originalRequest.newBuilder().header("Authorization",
getString(R.string.newsroom_api_key));
Request newRequest = builder.build();
return chain.proceed(newRequest);
}
}).build();
Retrofit.Builder builder =
new Retrofit.Builder()
.baseUrl(NewsroomAPI.BASE_URL)
.addConverterFactory(GsonConverterFactory.create());
Retrofit retrofit = builder.client(okHttpClient).build();
NewsroomAPI getNewsAPI = retrofit.create(NewsroomAPI.class);
Call<NewsList> call = getNewsAPI.loadNews("bbc-news");
call.enqueue(new Callback<NewsList>() {
@Override public void onResponse(Call<NewsList> call, Response<NewsList> response) {
if (response.isSuccessful()) {
NewsList newslist = response.body();
Log.w(TAG, "Articles result: " + newslist);
} else {
Toast.makeText(getContext(), "Some error occurred while fetching results!",
Toast.LENGTH_SHORT).show();
}
}
@Override public void onFailure(Call<NewsList> call, Throwable t) {
Log.w(TAG, "Failed! ", t);
}
});
當我運行活動並記錄結果時,問題就來了。 我希望看到status
和返回的articles
的日志。 但是,狀態已成功返回,但是articles
對象為null
。 輸出看起來像這樣;
W/GlobalNewsFragment: Articles result: ClassPojo [articles = null, status = ok]
問題似乎來自Retrofit2
反序列化返回的JSON對象的方式。 我做錯了什么嗎?
這些是我的build.gradle文件中的依賴項
compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'
compile "com.android.support:recyclerview-v7:26.1.0"
compile "com.squareup.okhttp3:okhttp:3.8.0"
您的POJO類應如下所示。
public class Article {
@SerializedName("source")
@Expose
private Source source;
@SerializedName("author")
@Expose
private String author;
@SerializedName("title")
@Expose
private String title;
@SerializedName("description")
@Expose
private String description;
@SerializedName("url")
@Expose
private String url;
@SerializedName("urlToImage")
@Expose
private String urlToImage;
@SerializedName("publishedAt")
@Expose
private String publishedAt;
// your getter setter methods
}
您的NewsList
POJO如下所示。
public class NewsList {
@SerializedName("status")
@Expose
private String status;
@SerializedName("articles")
@Expose
private List<Article> articles = null;
// getter setter
}
而您的source
POJO如下所示。
public class Source {
@SerializedName("id")
@Expose
private String id;
@SerializedName("name")
@Expose
private String name;
// getters setters
}
AFAIK Gson將JsonArray
反序列化為List
。 嘗試這個:
public class NewsList {
public List<Articles> articles;
private String status;
//some code
}
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