android使用SharedPreferences儲存資料

BaseAppCaching類封裝了SharedPreferences的操作。這是一個基礎類庫，可以用于多個項目。裡面将類對象轉換為Json，用的是Gson的庫。是以，提供了GsonUtil。但同時，為了解藕，也提供了ParseUtil類和IParseUtil協定。其中，ApplicationUtils.getApplication()，傳回的是全局的application，這裡替換成你自己的就行。

這是BaseAppCaching的代碼：

/**
 * @Author Lyf
 * @CreateTime 2018/3/1
 * @Description An BaseAppCaching class is caching data of app in SharePreference.
 *  data will be encrypted with Base64 when it cached in SP
 *  and decrypted with Base64 when it got from SP.
 **/
public class BaseAppCaching {

    private static BaseAppCaching mBaseAppCaching;

    protected static BaseAppCaching getAppCaching() {

        if (mBaseAppCaching == null) {
            synchronized (BaseAppCaching.class) {
                if (mBaseAppCaching == null) {
                    mBaseAppCaching = new BaseAppCaching();
                }
            }
        }

        return mBaseAppCaching;
    }

   /**
     * Uses a default key "BaseAppCaching" to save a class object in SP.
     */
    public <T> void saveAppCaching(T appCaching) {
        try {
            getSharedPreferences().edit().putString(this.getClass().getSimpleName(),
                    encryptCaching(ParseUtil.toJson(appCaching))).apply();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public <T> void saveAppCaching(String key, T appCaching) {
        try {
            getSharedPreferences().edit().putString(key,
                    encryptCaching(ParseUtil.toJson(appCaching))).apply();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

   /**
     * Uses a default key "BaseAppCaching" to get a object of T from SP.
     */
    @Nullable
    public <T> T getAppCaching(Class<T> tClass) {

        String json = getSharedPreferences().getString(this.getClass().getSimpleName(), null);

        if (json == null) {
            return null;
        }

        return ParseUtil.parseJson(decryptCaching(json), tClass);

    }

    @Nullable
    public <T> T getAppCaching(String key, Class<T> tClass) {

        String json = getSharedPreferences().getString(key, null);

        if (json == null) {
            return null;
        }

        return ParseUtil.parseJson(decryptCaching(json), tClass);

    }

    /**
     * encrypt json. You can rewrite this method in subclass.
     */
    protected String encryptCaching(String json) throws IOException {
        return new String(Base64.encode(json.getBytes(), Base64.DEFAULT));
    }

    /**
     * decrypt json. You can rewrite this method in subclass.
     */
    protected String decryptCaching(String json) {
        return new String(Base64.decode(json, Base64.DEFAULT));
    }

    private SharedPreferences getSharedPreferences() {

        if (ApplicationUtils.getApplication() == null) {
            throw new RuntimeException("You have to initialize the mContext before invoked this method!");
        }

        return ApplicationUtils.getApplication().getSharedPreferences(ApplicationUtils.getApplication().getPackageName(), Context.MODE_PRIVATE);
    }

}
           

這是ParseUtil的代碼：

public class ParseUtil {

    private static IParseUtil INSTANCE;

    private static IParseUtil getParseUtil() {

        if (INSTANCE == null) {
            synchronized (ParseUtil.class) {
                if (INSTANCE == null) {
                    // Instead of your parsing util if you need.
                    INSTANCE = new GsonUtil();
                }
            }
        }

        return INSTANCE;
    }

    public static <T> T parseJson(String json,  Class<T> tClass) {
        return getParseUtil().parseJson(json, tClass);
    }

    public static String toJson(Object object) {
        return getParseUtil().toJson(object);
    }

    public static <T> T parseInterfaceGenericJson(String json,  Class  tClass){
        return getParseUtil().parseInterfaceGenericJson(json,tClass);
    }

}
           

這是GsonUtil的代碼：

public class GsonUtil implements IParseUtil {

    private static Gson gson = new Gson();

    /**
     * Converts a json string into a T bean.
     */
    public static <T> T convertJson2Bean(String json, Class<T> tClass) {
        return gson.fromJson(json, tClass);
    }

    /**
     * Converts an object into a string.
     */
    public static String convertObject2Json(Object object) {
        return gson.toJson(object);
    }

    @Override
    public <T> T parseJson(String json,  Class<T> tClass) {
        return GsonUtil.convertJson2Bean(json, tClass);
    }

    @Override
    public <T> T parseInterfaceGenericJson(String json,  Class tClass) {
        return gson.fromJson(json, (((ParameterizedType)
                (tClass.getClass().getGenericInterfaces())[])
                .getActualTypeArguments()[]));
    }

    @Override
    public String toJson(Object object) {
        return GsonUtil.convertObject2Json(object);
    }

}
           

這是接口IParseUtil的代碼：

public interface IParseUtil {

    /**
     * Converts a json string into a T bean.
     */
     <T> T parseJson(String json,  Class<T> tClass);

    /**
     * Converts a json string into a T bean. T should be a Interface generic type.
     */
     <T> T parseInterfaceGenericJson(String json,  Class tClass);

    /**
     * Converts an object into a string.
     */
    String toJson(Object object);
}
           

這是實際使用示例：

/**
 * @Author Lyf
 * @CreateTime 2018/3/1
 * @Description An AppCaching class is caching data of app in SharePreference.
 **/
public class AppCaching extends BaseAppCaching {

    public static void saveUserInfo(IUserInfo userInfo) {
        getAppCaching().saveAppCaching(userInfo);
    }

    public static void saveSystemConfig(ISystemConfig systemConfig) {
        getAppCaching().saveAppCaching(systemConfig);
    }

    public static IUserInfo getUserInfo() {
        return getAppCaching().getAppCaching(IUserInfo.class);
    }

    public static ISystemConfig getSystemConfig() {
        return getAppCaching().getAppCaching(ISystemConfig.class);
    }

    public static <T> void saveData(String key, T tData) {
        getAppCaching().saveAppCaching(key, tData);
    }

    public static <T> T getData(String key, Class<T> tClass) {
        return getAppCaching().getAppCaching(key, tClass);
    }

    @Override
    protected String encryptCaching(String json) throws IOException {
        return super.encryptCaching(json);
    }

    @Override
    protected String decryptCaching(String json) {
        return super.decryptCaching(json);
    }
}
           

附上可以跑的項目(0 warnings, 0 errors):

代碼位于cache包下：

https://github.com/SuperBeagleDog/OkMVP