ios低级序列化

时间:2013-09-06 11:11:46

标签: android ios optimization serialization

这是一个Java / Android功能:

public static byte[] serialize(MyClass myObject) {

    int byteArraySizeNeeded = getByteArraySizeNeededForSerialize(myObject);

    byte[] result = new byte[byteArraySizeNeeded];
    ByteBuffer bb = ByteBuffer.wrap(result);
    bb.putShort((short) (byteArraySizeNeeded-2));// 2 - not need to read at deserialisation!

    bb.putLong(myObject.getProperty1ValueWhichIsALong());// 8
    bb.putDouble(myObject.getProperty2ValueWhichIsADouble());// 8
    bb.putFloat(myObject.getProperty3ValueWhichIsAFloat);//4
    bb.put(CODE_MYCODE1); // code
    bb.putFloat(myObject.getProperty4ValueWhichIsAFloat);

// there are a lot of properties and the list is dynamic: some need to be saved some not: eg if property 10 exists than not needed to save property 11 and property 25 is saved only if not null and so on.

    int curPosition = bb.position();
    int offset = 2; // skip the first 2 bytes representing the size of byte buffer needed to allocate.
    int byteCount = curPosition - offset;

    myObject.crc.update(result, offset, byteCount);
    long crcValue = myObject.crc.getValue();

    bb.put(CODE_CRC); // code
    bb.putLong(crcValue);// only distinct data values

    return result;
}

我也想在iOS上做。或者我想念或找不到低级数据结构/类使用什么。

NSDataNSMutableData声称是一个包装字节数组的对象,但它们有用的功能只有dataContentsOfFilewriteToFile

NSArchiver就像一个ObjectOutputStream。

Archives and Serializations Programming Guide 找不到任何不需要输入像encodeBytes这样的密钥的方法:length:forKey:

我不想重新发明轮子,也不想在保存时使用大量不必要的数据。

是否有任何实用程序类具有putLong()putFloat()putInt()并正确生成char或byte数组?

1 个答案:

答案 0 :(得分:1)

我找到了the same question,这个答案是基于它的。您可以使用NSOutputStream轻松创建一个与ByteBuffer实现相同接口的类。这样的事情:

- (NSOutputStream*)outputStream {
    if (_outputStream == nil) {
        _outputStream = [[NSOutputStream alloc] initToMemory];
        [_outputStream open];
    }
    return _outputStream;
}

- (void)putInt:(NSInteger)value {
    [self.outputStream write:(uint8_t*)&value maxLength:sizeof(NSInteger)];
}

- (NSData*)data {
    return [self.outputStream propertyForKey:NSStreamDataWrittenToMemoryStreamKey];
}