best way to compress in GZIP serialized objects in MEMORY

[Amer Seifeddine]

Hello,

I am looking for sample code to compress a serialized object in the memory (in a form of ByteArray or whatever) Say, Object o is the serialized object and i need to turn it into another Object z (compressed) as another variable. Do you have a sample?

Thanks!

[Ulf Dittmer]

Why are you trying to do this? Serialized object are in a binary format; I think it's unlikely that they can be compressed to any great degree.

[Amer Seifeddine]

Hi, that is not correct.. serialized objects are zipped up to 90% or more. do you have some sample code?

[Ernest Friedman-Hill]

Amer is right, actually. My experience with Jess's binary dump files is that GZIP can do about a factor of 5 on complex object graphs.

But in any case, serializing to a compressed byte array just looks like

ObjectOutputStream oos = new ObjectOutputStream(new GZIPOutputStream(new ByteArrayOutputStream(), 10000)));
oos.writeObject(myObject);
oos.close();
[ May 06, 2008: Message edited by: Ernest Friedman-Hill ]

[Guido Sautter]

Well, convert the serialized Object to an array of bytes, eg using a ByteArrayOutputStream, then run it through java.util.zip.Deflater to compress it.
See the Jave API documentation on how to use java.util.zip.Deflater (for compression) and java.util.zip.Inflater (for decompression). You'll also find code samples there.

[Amer Seifeddine]

Thanks. This is usefull to persist user session in memory if inactive instead of writing it to a file.