在 Android 的 Repository 或 ViewModel 中使用共享的 Preference 值

Question

我在我的 application.I 中使用 ArchitectureComponents 从 ViewModel 发出 API 请求并在 ActivityMain.For 中使用 ViewModel 将数据设置为 RecyclerView ] 进行 Api 调用我需要一个 Token 保存在 SharedPreference 中。我需要获取该令牌并将其添加到 Headers 中，同时进行 request.Where 和如何获取 SharedPreference 值。它应该在 ViewModel 或 Repository 中获取。
这是我的 ViewModel

的代码

public class FoodieViewModel extends AndroidViewModel {
   FoodieRepository repository;
   MutableLiveData<ArrayList<Foodie>> foodieList;
    public FoodieViewModel(@NonNull Application application) {
        super(application);
        repository=new FoodieRepository(application);
    }

     LiveData<ArrayList<Foodie>> getAllFoodie(){
        if(foodieList==null){
            foodieList=new MutableLiveData<ArrayList<Foodie>>();
            loadFoodies();
        }
        return foodieList;
    }
    public void loadFoodies(){
        String url="somethimg.com";
        JsonArrayRequest request =new JsonArrayRequest(Request.Method.GET, url, null, new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                ArrayList<Foodie> list=new ArrayList<>();
                try {
                    for(int i=0;i<response.length();i++){
                        JSONObject obj=response.getJSONObject(i);
                        Foodie foodie=new Foodie();
                        String name=obj.getString("firstname");
                        foodie.setName(name);
                        list.add(foodie);
                    }

                }catch (JSONException e){
                    e.printStackTrace();
                }
                foodieList.setValue(list);

            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        }){
            @Override
            public Map<String, String> getHeaders() throws AuthFailureError {
                Map<String, String> headers = new HashMap<>();
                String auth = "JWT " + "sometoken";
                headers.put("Authorization", auth);
                headers.put("Content-Type", "application/json");
                return headers;
            }

        };
        AppController.getInstance().addToRequestQueue(request);
    }

如果Token存储在SharedPreference中如何获取？

Answer 1

public class FoodieViewModel extends AndroidViewModel {
........
SharedPreferences sharedpreferences =getApplication().getSharedPreferences("preference_key", Context.MODE_PRIVATE);
...........

//wherever u want to get token
String token = sharedpreferences.getString("token", "")

}

Answer 2

您可以将 Context 传递给 ViewModel，例如：

ViewModel viewModel = new ViewModelProvider(this).get(UserViewModel.class);
   viewModel.setContext(new MutableLiveData<>(this));

然后用它来获取activity的任何资源。

在视图模型中：

SharedPreferences sharedPref = context.getValue().getSharedPreferences("myPref",Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPref.edit();
        editor.putString("token", token);
        editor.apply();

Answer 3

您可以在存储库 class 中的构造函数中创建一个 sharedPreference 对象。假设您已经创建了一个存储库 class (Singleton).

  //This class should be a singleton.
  public class YourRepositoryClass{
    //Initialize your token in your repository class's constructor
     String token=null;
    private YourRepositoryClass(Application application)
   {
     //your codes 

   //get your token in the repository and use whenever any viewmodel triggers repository to make a request
   // No need for getting token each time for different view models in case you are using multiple activities or fragments.


   SharedPreferences mPref=application.getSharedPreferences("preference_key",MODE_PRIVATE);
   token=mPref.getString("token",null);


        }

    // your other data request functions can be put here so that different view models can get data through this repository. Here use this token for making api requests.

  }

您不必为每个视图模型一次又一次地调用 SharedPreferences，并且每个视图模型都可以使用存储库轻松请求特定数据 class。

在 Android 的 Repository 或 ViewModel 中使用共享的 Preference 值

Use shared Preference values in Repository or ViewModel of Android

android

sharedpreferences

android-recyclerview

android-architecture-components