首先，我们将使用 Retrofit 进行网络请求，所以我们需要添加 Retrofit 的依赖。在你的 build.gradle 文件中添加以下依赖：

implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

接下来，我们创建一个接口来定义我们的 API 请求。假设我们的 API 是获取一些项目的列表：

import java.util.List;
import retrofit2.Call;
import retrofit2.http.GET;public interface ApiService {@GET("items")Call<List<Item>> getItems();
}

然后，我们创建一个 Repository 类来管理数据源，包括从网络获取数据：

import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;
import java.util.List;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;public class ItemRepository {private ApiService apiService;public ItemRepository(ApiService apiService) {this.apiService = apiService;}public LiveData<List<Item>> getItems() {MutableLiveData<List<Item>> data = new MutableLiveData<>();apiService.getItems().enqueue(new Callback<List<Item>>() {@Overridepublic void onResponse(Call<List<Item>> call, Response<List<Item>> response) {if (response.isSuccessful()) {data.setValue(response.body());}}@Overridepublic void onFailure(Call<List<Item>> call, Throwable t) {// 处理失败情况}});return data;}
}

接下来，我们创建一个 ViewModel 类来管理 UI 数据，并在其中调用 Repository 获取数据：

import androidx.lifecycle.LiveData;
import androidx.lifecycle.ViewModel;
import java.util.List;public class ItemViewModel extends ViewModel {private ItemRepository itemRepository;private LiveData<List<Item>> itemList;public ItemViewModel(ItemRepository itemRepository) {this.itemRepository = itemRepository;itemList = itemRepository.getItems();}public LiveData<List<Item>> getItemList() {return itemList;}
}

然后，我们创建一个 Fragment 类来显示项目列表：

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProvider;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.example.myapplication.databinding.FragmentItemBinding;
import java.util.List;public class ItemFragment extends Fragment {private FragmentItemBinding binding;@Overridepublic View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {binding = FragmentItemBinding.inflate(inflater, container, false);return binding.getRoot();}@Overridepublic void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {super.onViewCreated(view, savedInstanceState);ApiService apiService = RetrofitClient.getApiService();ItemRepository itemRepository = new ItemRepository(apiService);ItemViewModel viewModel = new ViewModelProvider(this, new ViewModelProvider.NewInstanceFactory()).get(ItemViewModel.class);binding.setViewModel(viewModel);binding.setLifecycleOwner(getViewLifecycleOwner());RecyclerView recyclerView = binding.recyclerView;recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));final ItemAdapter adapter = new ItemAdapter();recyclerView.setAdapter(adapter);viewModel.getItemList().observe(getViewLifecycleOwner(), new Observer<List<Item>>() {@Overridepublic void onChanged(List<Item> items) {adapter.setItemList(items);}});}
}

最后，我们创建一个 RecyclerView 的 Adapter 类：

import android.view.LayoutInflater;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.example.myapplication.databinding.ItemLayoutBinding;
import java.util.List;public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ItemViewHolder> {private List<Item> itemList;@NonNull@Overridepublic ItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {ItemLayoutBinding binding = ItemLayoutBinding.inflate(LayoutInflater.from(parent.getContext()), parent, false);return new ItemViewHolder(binding);}@Overridepublic void onBindViewHolder(@NonNull ItemViewHolder holder, int position) {Item item = itemList.get(position);holder.bind(item);}@Overridepublic int getItemCount() {return itemList != null ? itemList.size() : 0;}public void setItemList(List<Item> itemList) {this.itemList = itemList;notifyDataSetChanged();}static class ItemViewHolder extends RecyclerView.ViewHolder {private ItemLayoutBinding binding;ItemViewHolder(ItemLayoutBinding binding) {super(binding.getRoot());this.binding = binding;}void bind(Item item) {binding.setItem(item);binding.executePendingBindings();}}
}