55. 利用SharedPreferences做缓存

把数据写入缓存

    /**
     * 保存兑换专区商品列表
     * @param version
     */
    public static void saveExchangeProducts(Context context, ExchangeGroupProductListResponseVo exchangeGroupProductListResponseVo) {
        try {
            String jsonStr = new Gson().toJson(exchangeGroupProductListResponseVo);
            SharedPreferences sharedPreferences = context.getSharedPreferences(WalletThirdHelper.EXCHANGE_PRODUCT, 0);
            SharedPreferences.Editor editor = sharedPreferences.edit();
            editor.putString(WalletThirdHelper.EXCHANGE_PRODUCT, jsonStr);
            editor.apply();
        }catch (Exception e){
            e.printStackTrace();
        }

    }

从缓存中获取数据

/**
     * 获取缓存的兑换专区商品列表
     * @param version
     */
    private static ExchangeGroupProductListResponseVo getExchangeProducts(Context context) {

        try {

            SharedPreferences sharedPreferences = context.getSharedPreferences(WalletThirdHelper.EXCHANGE_PRODUCT, 0);
            String jsonStr = sharedPreferences.getString(WalletThirdHelper.EXCHANGE_PRODUCT, "");
            if (TextUtils.isEmpty(jsonStr)) return null;
            return new Gson().fromJson(jsonStr, ExchangeGroupProductListResponseVo.class);
        }catch (Exception e){
            e.printStackTrace();
            return null;
        }


    }

注意⚠️

开发过程中发现明明存进去了，但取不出数据。就把存数据按照下面处理：editor的获取和数据的存储分开书写：

SharedPreferences sharedPreferences = context.getSharedPreferences(WalletThirdHelper.EXCHANGE_PRODUCT, 0);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString(WalletThirdHelper.EXCHANGE_PRODUCT, jsonStr);
editor.apply();