SharedPreferences助手类

Question

我正在做SharedPreferences助手类,以使我的代码看起来不错.

public class SharedPreferencesHelper {
    Context context;

    public SharedPreferencesHelper(Context context){
        this.context = context;
    }

    public boolean isLogged(String prefs){
        return context.getSharedPreferences(prefs,Context.MODE_PRIVATE)
                      .getBoolean("LOGGED",false);
    }

    public void setLogged(String prefs){
        context.getSharedPreferences(prefs,Context.MODE_PRIVATE)
               .edit().putBoolean("LOGGED",true).apply();
    }
}

问题是我应该将这些方法设置为静态并在每个方法中初始化SharedPreferences或更好地保留它不是静态的,并从我的其他类中调用一次SharedPreferencesHelper类吗？谢谢

Answer 1

用这个 ：

public class SharedPreferencesHelper {

public static final String FILE_NAME = "APP_PREFERENCES";

  public static void put(Context context, String key, Object object) {

    SharedPreferences sp = context.getSharedPreferences(FILE_NAME,  Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sp.edit();
    if (object instanceof String) {
        editor.putString(key, (String) object);
    } else if (object instanceof Integer) {
        editor.putInt(key, (Integer) object);
    } else if (object instanceof Boolean) {
        editor.putBoolean(key, (Boolean) object);
    } else if (object instanceof Float) {
        editor.putFloat(key, (Float) object);
    } else if (object instanceof Long) {
        editor.putLong(key, (Long) object);
    } else {
        editor.putString(key, object.toString());
    }
    SharedPreferencesCompat.apply(editor);
}

   public static Object get(Context context, String key, Object defaultObject) {

    SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);

    if (defaultObject instanceof String) {
        return sp.getString(key, (String) defaultObject);
    } else if (defaultObject instanceof Integer) {
        return sp.getInt(key, (Integer) defaultObject);
    } else if (defaultObject instanceof Boolean) {
        return sp.getBoolean(key, (Boolean) defaultObject);
    } else if (defaultObject instanceof Float) {
        return sp.getFloat(key, (Float) defaultObject);
    } else if (defaultObject instanceof Long) {
        return sp.getLong(key, (Long) defaultObject);
    }

    return null;
}

public static void remove(Context context, String key) {
    SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sp.edit();
    editor.remove(key);
    SharedPreferencesCompat.apply(editor);
}

public static void clear(Context context) {
    SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = sp.edit();
    editor.clear();
    SharedPreferencesCompat.apply(editor);
}

public static boolean contains(Context context, String key) {
    SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
    return sp.contains(key);
}

public static Map<String, ?> getAll(Context context) {
    SharedPreferences sp = context.getSharedPreferences(FILE_NAME, Context.MODE_PRIVATE);
    return sp.getAll();
}



private static class SharedPreferencesCompat {
    private static final Method sApplyMethod = findApplyMethod();

    @SuppressWarnings({"unchecked", "rawtypes"})
    private static Method findApplyMethod() {
        try {
            Class clz = SharedPreferences.Editor.class;
            return clz.getMethod("apply");
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }

        return null;
    }

    public static void apply(SharedPreferences.Editor editor) {
        try {
            if (sApplyMethod != null) {
                sApplyMethod.invoke(editor);
                return;
            }
        } catch (IllegalArgumentException | IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }
        editor.commit();


    }
}
 }

Answer 2

我不会保留对上下文的引用。我宁愿将SharedPreference和 it保留Editor为辅助类的静态成员。这样，您就不需要SharedPreferencesHelper每次需要读/写SharedPreference. 更进一步，当您第一次访问助手本身时，将使用 Application Context（带有您的自定义 Application 子类）来初始化SharedPreference和。Editor这就是我塑造它的方式