android - 改造不解析数据

Question

我正在尝试使用 Retrofit 访问 Google News API，但在我的实现中遇到了问题，如果更有经验的人能看一眼我的代码，我将很高兴。问题是查询已成功构建并进入 response.isSuccessful()，但它没有任何条目。

我已确保 API 正常工作 ( http://ajax.googleapis.com/ajax/services/feed/find?v=1.0&q=technology )。此外，通过使用参数构建查询来使用 Postman 进行测试:

我用 http://www.jsonschema2pojo.org/ 生成了我的 pojo .以下是类(class):

NewsEntryApiEntry

public class NewsApiEntry {
    @SerializedName("url")
    @Expose
    private String url;
    @SerializedName("title")
    @Expose
    private String title;
    @SerializedName("contentSnippet")
    @Expose
    private String contentSnippet;
    @SerializedName("link")
    @Expose
    private String link;

    /**
     *
     * @return
     * The url
     */
    public String getUrl() {
        return url;
    }

    /**
     *
     * @param url
     * The url
     */
    public void setUrl(String url) {
        this.url = url;
    }

    /**
     *
     * @return
     * The title
     */
    public String getTitle() {
        return title;
    }

    /**
     *
     * @param title
     * The title
     */
    public void setTitle(String title) {
        this.title = title;
    }

    /**
     *
     * @return
     * The contentSnippet
     */
    public String getContentSnippet() {
        return contentSnippet;
    }

    /**
     *
     * @param contentSnippet
     * The contentSnippet
     */
    public void setContentSnippet(String contentSnippet) {
        this.contentSnippet = contentSnippet;
    }

    /**
     *
     * @return
     * The link
     */
    public String getLink() {
        return link;
    }

    /**
     *
     * @param link
     * The link
     */
    public void setLink(String link) {
        this.link = link;
    }

}

NewsApiResult

public class NewsApiResult {
    @SerializedName("query")
    @Expose
    private String query;
    @SerializedName("entries")
    @Expose
    private List<NewsApiEntry> entries = new ArrayList<NewsApiEntry>();

    /**
     *
     * @return
     * The query
     */
    public String getQuery() {
        return query;
    }

    /**
     *
     * @param query
     * The query
     */
    public void setQuery(String query) {
        this.query = query;
    }

    /**
     *
     * @return
     * The entries
     */
    public List<NewsApiEntry> getEntries() {
        return entries;
    }

    /**
     *
     * @param entries
     * The entries
     */
    public void setEntries(List<NewsApiEntry> entries) {
        this.entries = entries;
    }

}

改造服务生成器

public class NewsApiServiceGenerator {

    public static final String API_BASE_URL = "http://ajax.googleapis.com/ajax/services/feed/";
    private static OkHttpClient.Builder httpClient = new OkHttpClient.Builder();

    private static Gson gson = new GsonBuilder()
            .setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
            .create();

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

    public static <S> S createService(Class<S> serviceClass) {
        Retrofit retrofit = retroBuilder.client(httpClient.build()).build();
        return retrofit.create(serviceClass);
    }
}

最后，MainActivity:

public class MainActivity extends AppCompatActivity {
    public static List<NewsApiEntry> newsArticles;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);

        newsArticles= new ArrayList<>();
        fetchNewsArticles("technology");
    }

    private void fetchNewsArticles(String topic) {
        NewsApiClient client = NewsApiServiceGenerator.createService(NewsApiClient.class);

        Call<NewsApiResult> call = client.fetchNews("1.1", topic);
        call.enqueue(new Callback<NewsApiResult>() {
            @Override
            public void onResponse(Call<NewsApiResult> call, Response<NewsApiResult> response) {
                if(response.isSuccessful()) {
                    NewsApiResult res = response.body();
                    Log.d("API REQUEST URL: ", call.request().url().toString());
                    Log.d("API RESPONSE: ", response.raw().toString());
                    Log.d("API ENTRY COUNT: ", Integer.toString(res.getEntries().size()));
                    for(NewsApiEntry newsArticle : res.getEntries()) {
                        Log.d("API NEWS ENTRY TITLE: ", newsArticle.getTitle());
                        newsArticles.add(newsArticle);
                    }
                } else {
                    int statusCode = response.code();
                    ResponseBody errorBody = response.errorBody();
                    Log.e("Network Error: ", errorBody.toString());
                }
            }

            @Override
            public void onFailure(Call<NewsApiResult> call, Throwable t) {
                t.printStackTrace();
            }
        });
    }
}

这是日志:

查询已正确构建，响应的状态为 200，但为什么我没有收到充满条目的正文？注意:我的库已正确加载并且项目构建成功。

Answer 1

{"responseData": {"query":"technology","entries":[...]}}

看看你的NewsApiResult类是包含在 responseData 中的映射属性外部对象的属性。您还需要将该外部对象映射到一个新类，如下所示:

public class NewsApiResponse {
    @SerializedName("responseData")
    @Expose
    private NewsApiResult responseData;
    ...
}

并且您的 Retrofit 调用必须这样声明:

Call<NewsApiResponse> call = client.fetchNews("1.1", topic);

这应该可以解决您的问题。