我需要Android Studio中编程部分的帮助。
我有一个与我的数据库中的json数组相对应的RecyclerView。在这个数组中有一些填充RecyclerView的信息。每个json对象都有一个Web服务器上相应文件的URL。 在这一部分，我需要你的帮助。我需要从每个json对象获取URL并将相应的文件下载到设备并将其设置为RecyclerView行。
json中的URL名称为：download_url（目前不在我的代码中，而是在json数组中。
下载状态应显示在状态栏中，并带有进度视图（我需要在通知名称中添加一些信息）。当用户单击该行时，PDF文件应显示在PFD查看器中。 接下来是从设备中删除这些文件。如果用户刷新RecyclerView并且给定的json不再具有该文件，则应自动删除它们。 URL的末尾对应于服务器上的文件。 谢谢你的想法。我是初学者，并尽力从教程中学到很多东西，但这个问题对我来说非常困难和具体。
这是我的适配器：
public class PlansAdapter extends RecyclerView.Adapter<PlansAdapter.MyPlanHolder> {
private List<Plans> planList;
private final Context customContext;
public class MyPlanHolder extends RecyclerView.ViewHolder {
public TextView planTitle, planType, planDate;
public MyPlanHolder(View view) {
super(view);
planTitle = (TextView) view.findViewById(R.id.planTitle);
planType = (TextView) view.findViewById(R.id.planTyp);
planDate = (TextView) view.findViewById(R.id.planDate);
}
}
public PlansAdapter(List<Plans> planList, Context customContext) {
this.planList = planList;
this.customContext = customContext;
}
@Override
public MyPlanHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.plans_list_row, parent, false);
return new MyPlanHolder(itemView);
}
@Override
public void onBindViewHolder(MyPlanHolder holder, int position) {
final Plans plan = planList.get(position);
// Format timestamp to date
SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = null;
String resultDate = null;
try {
date = fmt.parse(plan.getPlanDate());
SimpleDateFormat fmtOut = new SimpleDateFormat("dd.MM.yyyy");
resultDate = fmtOut.format(date);
} catch (Exception e) {
e.printStackTrace();
}
holder.planTitle.setText(plan.getPlanTitle());
holder.planType.setText(plan.getEatingPlanType() + " " + plan.getTrainingPlanType());
holder.planDate.setText("resultDate);
}
@Override
public int getItemCount() {
return planList.size();
}
}
这是我的Request.class，我得到了json对象：
public class PlansRequest extends StringRequest {
public static final String PLANS_REQUEST_URL = "http://hiddenwebserver.de/de/json";
private Map<String, String> params;
public PlansRequest(String loginEmail, Response.Listener<String> listener) {
super(Request.Method.POST, PLANS_REQUEST_URL, listener, null);
params = new HashMap<>();
params.put("loginEmail", loginEmail);
}
@Override
public Map<String, String> getParams() {
return params;
}
}
这是我在Fragment上设置RecyclerView的地方：
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_training, container, false);
// Get Refresh Layout
swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.training_swiperefresh);
// Connectivity manager for network check
final ConnectivityManager connectivityManager = (ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
// Change color for the refresh layout
swipeRefreshLayout.setColorSchemeColors(Color.rgb(99, 195, 195));
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
// Check if network connection exists
if (connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED ||
connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
// Get plans data from web
getPlansData();
} else {
// Error message if internet connection is not available
Toast.makeText(getActivity(), getString(R.string.noInternetConnection), Toast.LENGTH_LONG).show();
}
}
});
trainingRecyclerView = (RecyclerView) view.findViewById(R.id.training_recycler_view);
pAdapter = new PlansAdapter(planList, getContext());
RecyclerView.LayoutManager pLayoutManager = new LinearLayoutManager(getActivity().getApplicationContext());
trainingRecyclerView.setLayoutManager(pLayoutManager);
trainingRecyclerView.setItemAnimator(new DefaultItemAnimator());
trainingRecyclerView.setAdapter(pAdapter);
preparePlansData();
return view;
}
这是我从json数组中准备数据的地方：
private void preparePlansData() {
// Connectivity manager for network check
final ConnectivityManager connectivityManager = (ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
// Check if network connection exists
if (connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED ||
connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
// Get shared preferences
SharedPreferences plansPreferenceData = getActivity().getSharedPreferences("plansData", MODE_PRIVATE);
if (plansPreferenceData.contains("plansPreferenceData")) {
String plansData = plansPreferenceData.getString("plansPreferenceData", "").replace("\"success\":true,", "");
// Remove success string from jsonResponse
//plansData.replace("success\":true,", "");
Log.d("plansData", "Result:" + plansData);
Gson gson = new Gson();
Type type = new TypeToken<Map<String, Plans>>(){}.getType();
Map<String, Plans> myPlansMap = gson.fromJson(plansData, type);
planList.addAll(myPlansMap.values());
// Notify data changes
pAdapter.notifyDataSetChanged();
// Now we call setRefreshing(false) to signal refresh has finished
swipeRefreshLayout.setRefreshing(false);
} else {
getPlansData();
}
} else {
// Error message if internet connection is not available
Toast.makeText(getActivity(), getString(R.string.noInternetConnectionOnStart), Toast.LENGTH_LONG).show();
}
}