使用sharedpreferences 保存 List<x

一、保存 List<xxx>

 /**
     * 保存List
     *
     * @param key
     * @param list
     */
    public static void putIntList(String key, List<Integer> list) {
        //获取SP的edit
        SharedPreferences.Editor editor = obtainPrefEditor();
        //保存集合的size大小
        editor.putInt(key + "_size", list.size());

        for (int i = 0; i < list.size(); i++) {
            //去掉旧的数据
            editor.remove(key + i);
            //添加新的数据
            editor.putInt(key + i, list.get(i));
        }
        SharedPreferencesCompat.apply(editor);
    } 

 /**
     * 获取List
     *
     * @param key
     * @return
     */
    public static List<Integer> getList(String key) {

        SharedPreferences sp = obtainPref();
        int size = sp.getInt(key + "_size", 0);

        List<Integer> list = new ArrayList<>();
        for (int i = 0; i < size; i++) {
            int anInt = sp.getInt(key + i, 0);
            list.add(anInt);
        }

        return list;
    }

二、保存 Object

/**
     * desc:保存对象
     *
     * @param key
     * @param obj 要保存的对象，只能保存实现了serializable的对象
     *            modified:
     */
    public static void putObject(String key, Object obj) {
        try {

            //先将序列化结果写到byte缓存中，其实就分配一个内存空间
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            ObjectOutputStream os = new ObjectOutputStream(bos);
            //将对象序列化写入byte缓存
            os.writeObject(obj);
            //将序列化的数据转为16进制保存
            String bytesToHexString = bytesToHexString(bos.toByteArray());
            //保存该16进制数组
            SharedPreferences.Editor editor = obtainPrefEditor();
            editor.putString(key, bytesToHexString);
            SharedPreferencesCompat.apply(editor);
        } catch (IOException e) {
            e.printStackTrace();
            Log.e("", "保存obj失败");
        }
    }   

 /**
     * desc:将数组转为16进制
     *
     * @param bArray
     * @return modified:
     */
    public static String bytesToHexString(byte[] bArray) {
        if (bArray == null) {
            return null;
        }
        if (bArray.length == 0) {
            return "";
        }
        StringBuffer sb = new StringBuffer(bArray.length);
        String sTemp;
        for (int i = 0; i < bArray.length; i++) {
            sTemp = Integer.toHexString(0xFF & bArray[i]);
            if (sTemp.length() < 2)
                sb.append(0);
            sb.append(sTemp.toUpperCase());
        }
        return sb.toString();
    }

 /**
     * desc:获取保存的Object对象
     *
     * @param key
     * @return modified:
     */
    public static Object getObject(String key) {
        try {
            SharedPreferences sp = obtainPref();
            String string = sp.getString(key, "");
            if (TextUtils.isEmpty(string)) {
                return null;
            } else {
                //将16进制的数据转为数组，准备反序列化
                byte[] stringToBytes = StringToBytes(string);
                ByteArrayInputStream bis = new ByteArrayInputStream(stringToBytes);
                ObjectInputStream is = new ObjectInputStream(bis);
                //返回反序列化得到的对象
                Object readObject = is.readObject();
                return readObject;
            }
        } catch (StreamCorruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //所有异常返回null
        return null;

    }

    /**
     * desc:将16进制的数据转为数组
     * <p>创建人：聂旭阳 , 2014-5-25 上午11:08:33</p>
     *
     * @param data
     * @return modified:
     */
    public static byte[] StringToBytes(String data) {
        String hexString = data.toUpperCase().trim();
        if (hexString.length() % 2 != 0) {
            return null;
        }
        byte[] retData = new byte[hexString.length() / 2];
        for (int i = 0; i < hexString.length(); i++) {
            int int_ch;  // 两位16进制数转化后的10进制数
            char hex_char1 = hexString.charAt(i); ////两位16进制数中的第一位(高位*16)
            int int_ch3;
            if (hex_char1 >= '0' && hex_char1 <= '9')
                int_ch3 = (hex_char1 - 48) * 16;   //// 0 的Ascll - 48
            else if (hex_char1 >= 'A' && hex_char1 <= 'F')
                int_ch3 = (hex_char1 - 55) * 16; //// A 的Ascll - 65
            else
                return null;
            i++;
            char hex_char2 = hexString.charAt(i); ///两位16进制数中的第二位(低位)
            int int_ch4;
            if (hex_char2 >= '0' && hex_char2 <= '9')
                int_ch4 = (hex_char2 - 48); //// 0 的Ascll - 48
            else if (hex_char2 >= 'A' && hex_char2 <= 'F')
                int_ch4 = hex_char2 - 55; //// A 的Ascll - 65
            else
                return null;
            int_ch = int_ch3 + int_ch4;
            retData[i / 2] = (byte) int_ch;//将转化后的数放入Byte里
        }
        return retData;
    }