Question

我正在使用此序列来设计应用程序：

（这些课程不会改变，我会用它们进行多项活动）

自定义适配器
模型类
共享偏好设置

Activity带有标签布局（包含两个片段），其中包含：

我要说出这个名字:(包＃1）

MainActivity
Fragment One
Fragment Two

现在我要复制 Package＃1 并更改一些内容，然后将其命名为Package＃2。但我这里有一个问题。

我正在使用Package＃1，Package＃2，Package＃3的一个共享首选项......，对吗？请查看我的共享偏好类：

public class SharedPreference_light {

    private SharedPreferences settings;
    private SharedPreferences.Editor editor;
    private Gson gson = new Gson();

    private static final String PREFS_NAME = "Light_Products";
    private static final String FAVORITES = "Favorite_Tones_Light";



    public SharedPreference_light(Context context) {
        settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        editor = settings.edit();
    }

    private void saveFavorites(List<ProductLocal> favorites) {
        String jsonFavorites = gson.toJson(favorites);
        editor.putString(FAVORITES, jsonFavorites);
        editor.apply();
    }

    public void addFavorite(ProductLocal product) {
        List <ProductLocal> favorites = getFavorites();
        if (favorites == null)
            favorites = new ArrayList<>();
        favorites.add(product);
        saveFavorites(favorites);
    }

    public void removeFavorite(ProductLocal product) {
        ArrayList <ProductLocal> favorites = getFavorites();
        if (favorites != null) {
            favorites.remove(product);
            saveFavorites(favorites);
        }
    }

    public ArrayList <ProductLocal> getFavorites() {
        List<ProductLocal> favorites;
        if (settings.contains(FAVORITES)) {
            String jsonFavorites = settings.getString(FAVORITES, null);
            ProductLocal[] favoriteItems = gson.fromJson(jsonFavorites, ProductLocal[].class);
            favorites = Arrays.asList(favoriteItems);
            favorites = new ArrayList <> (favorites);
        } else
            return null;

        return (ArrayList <ProductLocal> ) favorites;
    }
}

问题是如果我使用这两个变量：

private static final String PREFS_NAME = "Light_Products";
private static final String FAVORITES = "Favorite_Tones_Light";

这些包之间会有冲突。因为我要将一些列表项添加到共享首选项中并使用getSharedPreferences。那么多个包中的所有项目都将被添加到一个共享首选项中，我不希望这样。

现在我的真正问题是：

如何动态设置共享偏好设置名称（变量）？

注意： 我在自定义适配器中使用了一个共享首选项：

private boolean checkFavoriteItem(ProductLocal checkProduct) {
    boolean check = false;
    List<ProductLocal> favorites = sharedPreference.getFavorites();
    if (favorites != null) {
        for (ProductLocal product : favorites) {
            if (product.equals(checkProduct)) {
                check = true;
                break;
            }
        }
    }
    return check;
}

适配器：

public class LocalAdapter extends RecyclerView.Adapter<LocalAdapter.MyViewHolder>{

private SharedPreference_light sharedPreference;


public LocalAdapter(Activity activity, List<ProductLocal> dataList, RelativeLayout snackLayout) {
    this.snackLayout=snackLayout;
    this.activity = activity;
    this.dataList = dataList ;
    this.dataListFilter = dataList ;
    sharedPreference = new SharedPreference_light(activity);
    methods = new Methods(activity);
}

Answer 1

首先，您要使用提供包名称的接口：

public interface LightPrefs {

    String getPackageName();
}

其次，您可以重用您的类并使其实现以前的接口，但将其变为抽象：

public abstract class SharedPreference_light implements LightPrefs {

    private SharedPreferences settings;
    private SharedPreferences.Editor editor;

    protected final String PREFS_NAME = "Light_Products_" + getPackageName();
    protected final String FAVORITES = "Favorite_Tones_Light_" + getPackageName();

    public SharedPreference_light(Context context) {
        settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        editor = settings.edit();
    }

    private void saveFavorites(List<ProductLocal> favorites) {
        String jsonFavorites = gson.toJson(favorites);
        editor.putString(FAVORITES, jsonFavorites);
        editor.apply();
    }

    public void addFavorite(ProductLocal product) {
        List <ProductLocal> favorites = getFavorites();
        if (favorites == null)
        favorites = new ArrayList<>();
        favorites.add(product);
        saveFavorites(favorites);
    }

    public void removeFavorite(ProductLocal product) {
        ArrayList <ProductLocal> favorites = getFavorites();
        if (favorites != null) {
            favorites.remove(product);
            saveFavorites(favorites);
        }
    }

}

特别注意一些已更改的可见性修饰符。最后在你的包中扩展这个抽象类：

public class SharedPreference_package1 extends SharedPreference_light {

    private static final String TAG = "SharedPref_package1";

    public SharedPreference_package1(Context context) {
        super(context);
        Log.d(TAG, PREFS_NAME);
    }

    @Override
    public String getPackageName() {
        return "package#1";
    }
}

和

public class SharedPreference_package2 extends SharedPreference_light {

    private static final String TAG = "SharedPref_package2";

    public SharedPreference_package2(Context context) {
        super(context);
        Log.d(TAG, PREFS_NAME);
    }

    @Override
    public String getPackageName() {
        return "package#2";
    }
}

实例化这两个类可以为您提供此日志：

D/SharedPref_package1: Light_Products_package#1
D/SharedPref_package2: Light_Products_package#2

关于适配器，我认为你应该在构建时指定共享首选项对象：

public class LocalAdapter extends RecyclerView.Adapter<LocalAdapter.MyViewHolder>{

private SharedPreference_light sharedPrefs;

public LocalAdapter(Activity activity, List<ProductLocal> dataList, RelativeLayout snackLayout, SharedPreference_light sharedPrefs) {
    this.snackLayout=snackLayout;
    this.activity = activity;
    this.dataList = dataList ;
    this.dataListFilter = dataList ;
    this.sharedPrefs = sharedPrefs;
    methods = new Methods(activity);
}

因此，您可以在包＃1中初始化您的适配器：

SharedPreference_package1 sharedPrefs = new SharedPreference_package1();

LocalAdapter adapter = new LocalAdapter(activity, dataList, snackLayout, sharedPrefs);

您可以在第二个包中使用SharedPreference_package2。

希望这会对你有所帮助。

Answer 2

使所有方法将共享首选项键作为参数，如：

public SharedPreference_light(Context context, String name);
private void saveFavorites(List<ProductLocal> favorites, String name);
public void addFavorite(ProductLocal product, String name);
public void removeFavorite(ProductLocal product, String name);
public ArrayList <ProductLocal> getFavorites(String name);

动态设置SharedPreferences名称

2 个答案: