Serialization with Streams in Java
In C++, I've created a class called Serializer. And I want to duplicate the functionality in Java. Here's how Serializer works.
开发者_StackOverflow中文版Serializer s;
s.writeString(myString); // automatically converted to Big-Endian unicode string with length prepended.
s.writeInt(myInt); // automatically converted to Big-Endian integer (swizzled if necessary)
s.writeObject(myObject); // which implements the Serializable interface
{
s.writeInt(myObjectId); // internally, it writes the data that I want to serialize.
...
}
ZlibCompressor.compress(s); // 's' is compressed
{
bytes = s.getBytes(); // internally, it gets bytes, ...
compressFunc(bytes); // compress them
s.overwrite(bytes); // and overwrites
}
AESCipher.encrypt(s); // similarly, 's' is encrypted
// and the reverse in the same file, using the same all-in-one class to manipulate byte data.
AESCipher.decrypt(s);
ZlibCompressor.decompress(s);
s.readString(myString);
s.readInt(myInt);
s.readObject(myObject);
And of course, these are the other few functions you can do (copied and pasted from C++):
ByteArray Split(const Uint32& start, const Uint32& size);
inline Uint32 GetSize() const { return mBytes.size(); }
inline const Uint32& GetPos() const { return mPos; }
inline Bool IsEmpty() const { return mBytes.empty(); }
inline const Bool& IsError() const { return mError; }
inline void Resize(const Uint32& size, const Byte& val = 0) { mBytes.resize(size, val); }
inline void SetPos(const Uint32& pos) const { mPos = pos; }
inline void Reset() const { mPos = 0; mError = false; }
inline void Clear() { mBytes.clear(); Reset(); }
inline void Push(const Byte& x) { mBytes.push_back(x); }
inline void Pop() { mBytes.pop_back(); }
- Is there any in-built class that does that, freely able to manipulate byte data?
- If there isn't, can you use the Input and Output stream together?
- If you can't, how do you convert between InputStream and OutputStream?
- Is there any other approach to solving this problem?
Side Note: All the byte data can be in memory. Memory is not an issue.
Thank you.
Java has an object serialisation system, which sounds like a good fit for what you want to do. Quick summary:
- Have your class implement
java.io.Serializable
, and add aprivate static final long serialVersionUID
field (use any value you like---usually I just start with 1). - Mark all fields you don't want to serialise as
transient
; all non-transient
fields will be serialised. - Ensure that all fields you want to serialise are either primitive or are also serialisable types---all non-serialisable types must be transient.
- Change the
serialVersionUID
whenever you make changes to the fields that get serialised. Usually I just bump the value by 1. - For custom serialisation, you can implement the
readObject
andwriteObject
methods. - For seriously custom serialisation, there's also
java.io.Externalizable
.
To actually serialise or deserialise your objects, use the DataOutputStream
and DataInputStream
classes. And yes, you can wrap the streams with compression and/or encryption. :-)
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