Question

我在Android的“回收视图”中显示数据时遇到问题。数据来自一个API，该API在我单独测试时可以正常工作。我已经实现了DTO模式，因为数据位于主JSON内的数据JSON内。我正在使用Retrofit从API获取数据。我将在下面保留代码

ArticleActivity.Java

public class ArticleActivity extends AppCompatActivity {
private final String baseUrl = "http://127.0.0.1:3000/";
List<Article> listaArticles = new ArrayList<>();
ArticleAdapter adapter;
RecyclerView rvClientes;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_article);

    rvClientes = (RecyclerView) findViewById(R.id.rvClientes);  // change this ID

    Retrofit retrofit = new Retrofit.Builder().baseUrl(baseUrl)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    LinearLayoutManager llm = new LinearLayoutManager(getApplicationContext());
    rvClientes.setLayoutManager(llm);

    adapter =  new ArticleAdapter(listaArticles);
    rvClientes.setAdapter(adapter);

    DividerItemDecoration itemDecoration = new DividerItemDecoration(rvClientes.getContext(),llm.getOrientation());
    rvClientes.addItemDecoration(itemDecoration);

    ArticleService articleService = retrofit.create(ArticleService.class);

    Call<ArticlesDTO> callArticleDTO = articleService.getArticles();
    callArticleDTO.enqueue(new Callback<ArticlesDTO>() {
        @Override
        public void onResponse(Call<ArticlesDTO> call, Response<ArticlesDTO> response) {
            if(response.isSuccessful()) {
                listaArticles = response.body().data;
                adapter = new ArticleAdapter(listaArticles);
                rvClientes.setAdapter(adapter);
                adapter.notifyDataSetChanged();
            }
        }

        @Override
        public void onFailure(Call<ArticlesDTO> call, Throwable t) {

        }

    });
   }
}

ArticleAdapter.Java

public class ArticleAdapter extends RecyclerView.Adapter<ArticleAdapter.ArticleViewHolder> {

    List<Article> lista;


    public ArticleAdapter(List<Article> lista) {
        this.lista = lista;
    }

    @Override
    public ArticleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.article_row,parent,false);
        return new ArticleViewHolder(v);
    }

    @Override
    public void onBindViewHolder(ArticleViewHolder holder, int position) {
        holder.bindArticle(lista.get(position));
    }

    @Override
    public int getItemCount() {
        return lista.size();
    }

    public class ArticleViewHolder extends RecyclerView.ViewHolder {

        TextView tvNombre;
        TextView tvId;



        public ArticleViewHolder(View itemView) {
            super(itemView);
            tvNombre = (TextView) itemView.findViewById(R.id.tvArticle);
            tvId = (TextView) itemView.findViewById(R.id.tvID);

        }

        public void bindArticle(Article article) {
            String nombre = article.getTitle() + ":";
            tvNombre.setText(nombre);
            tvId.setText(String.valueOf(article.getId()));
        }

    }
}

ArticlesDTO

public class ArticlesDTO {
     public String status;
     public String message;
     public List<Article> data;

}

ArticleService

public interface ArticleService {
    @GET("api/v1/articles")
    Call<ArticlesDTO> getArticles();
}

问题是，当我打开该应用程序时，它只显示黑屏，没有任何错误。我使用断点检查数组列表的大小，它为零

Answer 1

每当从API获得响应时，您都将设置一个新适配器

//here is the problem

if (response.isSuccessful()) {
   listaArticles = response.body().data;
   adapter = new ArticleAdapter(listaArticles);
   rvClientes.setAdapter(adapter);
   adapter.notifyDataSetChanged();
}

代替使用现有适配器，然后将数据添加到适配器

public void addAll(List<Article> data){
   this.lista = data;
   notifyDataSetChanged();
}

，然后当您获得回复

if (response.isSuccessful()) {
   listaArticles = response.body().data;
   adapter.addAll(listaArticles);
}

Answer 2

似乎您输入了错误的网址（http://127.0.0.1:3000/）这是一个localhost网址，不能用于android设备。尝试在云上部署后端服务，并为android应用提供适当的基本URL。

无法从Android中的API获取数据

2 个答案: