Question

我目前正在实现我的应用程序的数据层，并且想知道从相应的android资源（如字符串，颜色等）中分离纯数据类/信息的最佳方法。

例如：

public final class Location {
    public static final int NOT_SPECIFIED = 0;
    public static final int AT_HOME = 1;
    public static final int AT_WORK = 2;
    public static final int AWAY = 3;

    public static final int[] VALUES = {
            NOT_SPECIFIED, AT_HOME, AT_WORK, AWAY
    };

    @IntDef({ NOT_SPECIFIED, AT_HOME, AT_WORK, AWAY })
    @Retention(RetentionPolicy.SOURCE)
    public @interface Locations {}

    private static String TXT_NOT_SPECIFIED;
    private static String TXT_AT_HOME;
    private static String TXT_AT_WORK;
    private static String TXT_AWAY;

    private Location() {}

    /**
     * Call once in Application.class to get a reference to the application context
     * in order to load the string representations for the single locations.
     *
     * @param applicationContext the app´s context
     */
    public static void init(Context applicationContext) {
        Resources res = applicationContext.getApplicationContext().getResources();

        /* Pre-load any string resources that correspond to locations. */
        TXT_NOT_SPECIFIED = res.getString(R.string.text_location_not_specified);
        TXT_AT_HOME = res.getString(R.string.text_location_at_home);
        TXT_AT_WORK = res.getString(R.string.text_location_at_work);
        TXT_AWAY = res.getString(R.string.text_location_away);
    }

    /**
     * Returns the string representation of a given <code>location</code>.
     *
     * @param location must be in range of 0-3
     *uhr
     * @return the string representing the <code>location</code>
     */
    public static String getStringForLocation(@Locations int location) {
        switch (location) {
            case NOT_SPECIFIED: return TXT_NOT_SPECIFIED;
            case AT_HOME: return TXT_AT_HOME;
            case AT_WORK: return TXT_AT_WORK;
            case AWAY: return TXT_AWAY;
        }
        throw new IllegalStateException("'location' must be in range of 0-3");  /* Should never be called actually. */
    }

类本身包含某些位置的纯数据表示（而不是使用enum）。对于每个定义的location，存在strings.xml文件中的字符串表示。＃现在的问题是：我的应用的多个部分需要获取某个location的名称。而不是每次我希望它们存储在一个地方时都找到资源，以便在某些内容发生变化时（添加新的location选项等），我只需要在一个地方触摸代码。

目前我已经像上面的代码所示实现了它：Location类有一个静态init方法，在App的onCreate中调用它来获取context以加载字符串resoruces。（我知道我可能刚刚将context作为getStringForLocation方法的参数传递，无法确定哪一个更好？）

然而，这种方式我在我假设的纯数据类中有android依赖。在保持将数据映射到一个地方的资源的代码的同时，分离这些依赖关系的好方法是什么？在数据层外部使用静态util方法进行映射？

Answer 1

我不太明白为什么要在某些变量中预加载字符串。我的理解是从资源中获取字符串在性能方面并不昂贵。

我只是使用这样的东西：

public static String getLocationString(Context context, @Locations int location) {

    switch (location) {
        case NOT_SPECIFIED: return context.getString(R.string.text_location_not_specified);
        case AT_HOME: return context.getString(R.string.text_location_at_home);
        case AT_WORK: return context.getString(R.string.text_location_at_work);
        case AWAY: return context.getString(R.string.text_location_away);
    }

    throw new IllegalStateException("'location' must be in range of 0-3");  /* Should never be called actually. */

}

来自活动：

String myLocation = Location.getLocationString(this, Location.AT_HOME);

你可以摆脱Location.init方法

Android：如何从资源中分离纯数据？

1 个答案: