Обсуждение: persistence of java objects

hi,

Does postgresql support this? if i want a column of a table for the
persistence of instance of java objects, and use ResultSet.getObject() and
ResultSet.updateObjecct() to access them. if so, what data type the column
should be?

thanks
zhenchang

Hi,

postgresql doesn't support this they way I suspect you are thinking of it.

How do other databases do this ?

dave

jessica xingzc_he wrote:

> hi,
>
> Does postgresql support this? if i want a column of a table for the
> persistence of instance of java objects, and use ResultSet.getObject()
> and ResultSet.updateObjecct() to access them. if so, what data type
> the column should be?
>
> thanks
> zhenchang
>
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
>
>

--
Dave Cramer
http://www.postgresintl.com
519 939 0336
ICQ#14675561

On Sunday 31 October 2004 01:05, jessica xingzc_he wrote:
> hi,
>
> Does postgresql support this? if i want a column of a table for the
> persistence of instance of java objects, and use ResultSet.getObject() and
> ResultSet.updateObjecct() to access them. if so, what data type the column
> should be?

If you use a standard type like integer or varchar, you can do things like

setObject(1,new Integer(5));
setObject(2,"something");

which would be equivalent to

setInteger(1,new Integer(5));
setString(2,"something");

If you want to store complex objects in the database then they should
implement the java.io.serializable interface. Thereby you can store them in a
byteArray or push them into a bytearraystream and write the result with the
usual methods into the database.
A simple serialization example is here for java.io.File:

http://java.sun.com/j2se/1.3/docs/guide/serialization/spec/examples.doc1.html

Regards,

Uli

Hi, Jessica,

On Sat, 30 Oct 2004 17:05:44 -0600
"jessica xingzc_he" <xingzc_he@hotmail.com> wrote:

> Does postgresql support this? if i want a column of a table for the
> persistence of instance of java objects, and use ResultSet.getObject() and
> ResultSet.updateObjecct() to access them. if so, what data type the column
> should be?

Currently, there's no support for general Java objects.

But maybe what you really need is a persistance framework. Hibernate
currently seems to be a reasonable one, and it supports PostgreSQL.

HTH,
Markus

--
markus schaber | dipl. informatiker
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