我想在fragments中显示3 Activity，并在任何json中加载来自 fragments 的数据！我需要使用Recyclerview库将网站数据显示到OkHTTP v3。
我想将此数据显示为离线，我的意思是，如果用户关闭数据/ wifi，则显示离线的此数据。但我不想使用 SQLite数据库！
对于这个想法，我使用SharedPreference来保存数据，并在禁用网络节目时显示来自此Preference的离线数据。
我写下面的代码，但当禁用网络不显示我的数据离线 !!
AsyncTask代码：
public class freeDataInfo {
private Context mContext;
private String ServerAddress = freeServer_IP.getFreeIP();
public void getFreeDataInfo(Context context) {
mContext = context;
//new getInfo().execute(ServerAddress + "limit=10");
new getInfo().execute(ServerAddress);
}
private class getInfo extends AsyncTask<String, Void, String> {
EventBus bus = EventBus.getDefault();
private String ou_response;
private List<DataModel> infoModels = new ArrayList<>();
private ProgressDialog dialog;
@Override
protected void onPreExecute() {
//CustomProcessDialog.createAndShow(mContext);
//infoModels = new ArrayList<>();
// Initiate Progress
dialog = new ProgressDialog(mContext);
this.dialog.setMessage("شکیبا باشید...");
this.dialog.show();
infoModels.clear();
}
@Override
protected String doInBackground(String... params) {
OkHttpClient client = new OkHttpClient();
//String url = (String) params[0];
Request request = new Request.Builder()
//.url(ServerAddress + "limit=10")
.url(ServerAddress)
.cacheControl(CacheControl.FORCE_NETWORK)
.build();
Response response;
try {
response = client.newCall(request).execute();
ou_response = response.body().string();
response.body().close();
if (ou_response != null) {
try {
JSONObject postObj = new JSONObject(ou_response);
JSONArray postsArray = postObj.optJSONArray("result");
for (int i = 0; i <= postsArray.length(); i++) {
JSONObject postObject = (JSONObject) postsArray.get(i);
int id = postObject.getInt("id");
Log.d("id", String.valueOf(id));
String title = postObject.getString("title");
String description = postObject.getString("full_description");
String image = postObject.getString("image");
String category = postObject.getString("categoryName");
String date = postObject.getString("date");
String url = postObject.getString("url");
Log.d("Data", "Post ID: " + id);
Log.d("Data", "Post title: " + title);
Log.d("Data", "Post image: " + image);
Log.d("Data", "Post url: " + url);
Log.d("Data", "---------------------------------");
//Use the title and id as per your requirement
infoModels.add(new DataModel(id, title, description, category, date, url, image));
}
} catch (JSONException e) {
e.printStackTrace();
Log.e("error", String.valueOf(e));
}
}
} catch (IOException e) {
e.printStackTrace();
Log.e("error2", String.valueOf(e));
}
return ou_response;
}
@Override
protected void onPostExecute(String result) {
//CustomProcessDialog.dissmis();
//Stop Progress
if (dialog.isShowing()) {
dialog.dismiss();
}
if (result != null) {
bus.post(new MyEvent("forfragment1", infoModels));
} else {
//Toast.makeText(mContext, "اتصال اینترنت خود را بررسی کنید", Toast.LENGTH_LONG).show();
if (isNetworkStatusAvialable(mContext)) {
//Here your normal parsing while network available
SharedPreferences app_preferences1 = PreferenceManager.getDefaultSharedPreferences(mContext);
SharedPreferences.Editor editor = app_preferences1.edit();
editor.putString("jsonResponse", ou_response);
editor.commit();
} else {
final SharedPreferences app_preferences1 = PreferenceManager.getDefaultSharedPreferences(mContext);
String response = app_preferences1.getString("jsonResponse", "");
try {
JSONObject postObj = new JSONObject(response);
JSONArray postsArray = postObj.optJSONArray("result");
for (int i = 0; i <= postsArray.length(); i++) {
JSONObject postObject = (JSONObject) postsArray.get(i);
int id = postObject.getInt("id");
Log.d("id", String.valueOf(id));
String title = postObject.getString("title");
String description = postObject.getString("full_description");
String image = postObject.getString("image");
String category = postObject.getString("categoryName");
String date = postObject.getString("date");
String url = postObject.getString("url");
Log.d("Data", "Post ID: " + id);
Log.d("Data", "Post title: " + title);
Log.d("Data", "Post image: " + image);
Log.d("Data", "Post url: " + url);
Log.d("Data", "---------------------------------");
//Use the title and id as per your requirement
infoModels.add(new DataModel(id, title, description, category, date, url, image));
}
} catch (JSONException e) {
e.printStackTrace();
Log.e("error", String.valueOf(e));
}
}
}
}
}
public static boolean isNetworkStatusAvialable(Context context) {
ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivityManager != null) {
NetworkInfo netInfos = connectivityManager.getActiveNetworkInfo();
if (netInfos != null)
if (netInfos.isConnected())
if (netInfos.isAvailable())
return true;
}
return false;
}
}
片段代码：
public class free_fragment extends Fragment {
private RecyclerView mRecyclerView;
private free_recycler_adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
private List<DataModel> dataModels = new ArrayList<DataModel>();
private List<DataModel> infoModels = new ArrayList<>();
//private ArrayList<DataModel> dataModels;
private Context context;
private boolean isDataFetched;
private boolean mIsVisibleToUser;
private View view;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_free_layout, container, false);
context = getContext();
if (mIsVisibleToUser) {
LoadData();
}
///----- RecyclerView -----
mRecyclerView = (RecyclerView) view.findViewById(R.id.pdf_RecyclerView);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
mAdapter = new free_recycler_adapter(context, dataModels);
mRecyclerView.setAdapter(mAdapter);
return view;
}
@Subscribe
public void onEvent(MyEvent event) {
List<DataModel> dataModels = event.getInfoModels();
if (dataModels.size() > 0) {
dataModels.remove(dataModels.size() - 1);
mAdapter.notifyItemRemoved(dataModels.size());
//mAdapter.setLoaded();
}
if (event.fragmentTag.equals("forfragment1")) {
mAdapter.add(dataModels);
isDataFetched = true;
mAdapter.notifyDataSetChanged();
}
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
mIsVisibleToUser = isVisibleToUser;
if (isVisibleToUser && !isDataFetched && getContext() != null) {
context = getContext();
LoadData(); //Remove this call from onCreateView
}
}
private void LoadData() {
freeDataInfo dataInfo = new freeDataInfo();
// here getMainDataInfo() should return the server response
dataInfo.getFreeDataInfo(context);
}
@Override
public void onResume() {
super.onResume();
EventBus.getDefault().register(this);
}
@Override
public void onPause() {
EventBus.getDefault().unregister(this);
super.onPause();
}
适配器代码：
public class free_recycler_adapter extends RecyclerView.Adapter<free_recycler_adapter.ViewHolder> {
private List<DataModel> mDateSet;
private Context context;
private ArrayList<DataModel> mModels;
// Provide a suitable constructor (depends on the kind of dataset)
public free_recycler_adapter(Context context, List<DataModel> dataSet) {
this.context = context;
this.mDateSet = dataSet;
}
public free_recycler_adapter(ArrayList<DataModel> models) {
this.mModels = models;
}
// Create new views (invoked by the layout manager)
@Override
public free_recycler_adapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// create a new view
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.free_card_layout, parent, false);
// create ViewHolder
return new ViewHolder(view);
}
// Replace the contents of a view (invoked by the layout manager)
@Override
public void onBindViewHolder(ViewHolder viewHolder, final int position) {
// - get data from your itemsData at this position
// - replace the contents of the view with that itemsData
viewHolder.free_titleText.setText(Html.fromHtml(mDateSet.get(position).getTitle()));
Glide.with(context)
.load(mDateSet.get(position).getImage())
.placeholder(R.drawable.ic_download_image)
.override(200, 200)
.crossFade(500)
.into(viewHolder.free_avatarImage);
viewHolder.free_descText.setText(Html.fromHtml(mDateSet.get(position).getDescription()));
viewHolder.free_descText.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
v.getContext().startActivity(new Intent(v.getContext(), ContentPage.class)
.putExtra("title", mDateSet.get(position).getTitle())
.putExtra("desc", mDateSet.get(position).getDescription())
.putExtra("image", mDateSet.get(position).getImage())
.putExtra("url", mDateSet.get(position).getUrl())
.putExtra("category", mDateSet.get(position).getCategory())
.putExtra("date", mDateSet.get(position).getDate()));
}
});
}
// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
return mDateSet.size();
}
public void remove(int position) {
mDateSet.remove(position);
notifyItemRemoved(position);
}
public void clear() {
mDateSet.clear();
notifyDataSetChanged();
}
public void add(List<DataModel> models) {
mDateSet.addAll(models);
notifyDataSetChanged();
}
public void update(List<DataModel> models) {
mDateSet.clear();
mDateSet.addAll(models);
notifyDataSetChanged();
}
// inner class to hold a reference to each item of RecyclerView
public static class ViewHolder extends RecyclerView.ViewHolder {
public TextView free_titleText, free_descText;
public ImageView free_avatarImage;
public ViewHolder(View itemLayoutView) {
super(itemLayoutView);
free_titleText = (TextView) itemLayoutView.findViewById(R.id.pdf_card_title);
free_descText = (TextView) itemLayoutView.findViewById(R.id.pdf_card_content);
free_avatarImage = (ImageView) itemLayoutView.findViewById(R.id.pdf_card_image);
}
}
}
如何解决此问题并使用 sharedPreferences 显示数据（离线）？谢谢所有＆lt; 3
答案 0 :(得分：0)
你不应该使用SharedPreferences，这不是它们的用途。您可以使用OkHttp缓存网络响应，以便在用户离线时投放。
将Interceptor写入缓存回复。
/** Dangerous interceptor that rewrites the server's cache-control header. */
private static final Interceptor REWRITE_CACHE_CONTROL_INTERCEPTOR = new Interceptor() {
@Override public Response intercept(Interceptor.Chain chain) throws IOException {
Response originalResponse = chain.proceed(chain.request());
return originalResponse.newBuilder()
.header("Cache-Control", "max-age=60")
.build();
}
};
现在写另一个Interceptor以在离线时返回数据：
private static final Interceptor OFFLINE_INTERCEPTOR = new Interceptor() {
@Override
public Response intercept(Interceptor.Chain chain) throws IOException {
Request request = chain.request();
if(!AppUtils.isOnline()) { // Checks if offline
int maxStale = 60 * 60 * 12; // tolerate 12 hours stale data
request = request.newBuilder()
.header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
.build();
}
return chain.proceed(request);
}
};
最后，将这两个添加到OkHttp客户端：
OkHttpClient okHttpClient = new OkHttpClient().newBuilder().addNetworkInterceptor(REWRITE_CACHE_CONTROL_INTERCEPTOR)
.addInterceptor(OFFLINE_INTERCEPTOR)
.build();