Save user data where?

[Karsten Wutzke]

Hi all!

I wish to save some user data (editable via GUI) on a per user basis.

Is there any nice mechanism in Java that puts such info into an
appropriate place? If I have to do that manually, what would be a nice
place to save some small files with bothering the user? Or shall I
force every user to specify a directory?

Karsten

 

[Knute Johnson]

Hi all!

I wish to save some user data (editable via GUI) on a per user basis.

Is there any nice mechanism in Java that puts such info into an
appropriate place? If I have to do that manually, what would be a nice
place to save some small files with bothering the user? Or shall I
force every user to specify a directory?

Karsten

Look at the system property user.home.

 

[Karsten Wutzke]

Look at the system property user.home.

I know this. But I don't want to create files or directories "unasked"
which will clutter the user's home dir and make some users really mad
(as I would be).

Karsten

 

[Thomas Fritsch]

I wish to save some user data (editable via GUI) on a per user basis.

Is there any nice mechanism in Java that puts such info into an
appropriate place? If I have to do that manually, what would be a nice
place to save some small files with bothering the user? Or shall I
force every user to specify a directory?

Sounds like you need java.util.prefs.Preferences.

You can get a handle to the user's preferences by:
Preferences prefs =
Preferences.userNodeForPackage(my.package.Main.class);
Java keeps the user's preferences in a platform-specific place:
(*) for Windows: in a certain user-specific branch of the registry
(*) for Unix/Linux: in a certain hidden file in the user's home dir.
But you don't have to care about those details.

You read/write specific key/value like this:
String value = prefs.get(key);
prefs.get(key, value);

For more details see the API docs
<http://java.sun.com/j2se/1.5.0/docs/api/java/util/prefs/Preferences.html>
<http://java.sun.com/j2se/1.5.0/docs...nces.html#userNodeForPackage(java.lang.Class)>

 

[Jason Cavett]

Sounds like you need java.util.prefs.Preferences.

You can get a handle to the user's preferences by:
Preferences prefs =
Preferences.userNodeForPackage(my.package.Main.class);
Java keeps the user's preferences in a platform-specific place:
(*) for Windows: in a certain user-specific branch of the registry
(*) for Unix/Linux: in a certain hidden file in the user's home dir.
But you don't have to care about those details.

You read/write specific key/value like this:
String value = prefs.get(key);
prefs.get(key, value);

For more details see the API docs
<http://java.sun.com/j2se/1.5.0/docs/api/java/util/prefs/Preferences.html>
<http://java.sun.com/j2se/1.5.0/docs/api/java/util/prefs/Preferences.h...)>

There wouldn't be any problem with permissions using this method,
would there? (AKA - The user can't write to the registry.)

 

[angrybaldguy]

There wouldn't be any problem with permissions using this method,
would there? (AKA - The user can't write to the registry.)

The default Sun implementation on Windows stores preferences in a node
under HKEY_CURRENT_USER, which is always writable by the current user
and is normally made part of the user's profile, whether local or
roaming.

So no, not really.

 

[Knute Johnson]

I know this. But I don't want to create files or directories "unasked"
which will clutter the user's home dir and make some users really mad
(as I would be).

Karsten

Then store it on a remote server. I really don't think that makes any
sense but it accomplishes what you want; a file but not on the users
computer.

When I look in my Windoze computer home directory I can find 25 folders
of stuff that applications have put there. That is where that kind of
stuff belongs. I didn't look at my Linux home directory but I know
there is a lot of application data there too.

 

[Knute Johnson]

Sounds like you need java.util.prefs.Preferences.

You can get a handle to the user's preferences by:
Preferences prefs =
Preferences.userNodeForPackage(my.package.Main.class);
Java keeps the user's preferences in a platform-specific place:
(*) for Windows: in a certain user-specific branch of the registry
(*) for Unix/Linux: in a certain hidden file in the user's home dir.
But you don't have to care about those details.

You read/write specific key/value like this:
String value = prefs.get(key);
prefs.get(key, value);

For more details see the API docs
<http://java.sun.com/j2se/1.5.0/docs/api/java/util/prefs/Preferences.html>
<http://java.sun.com/j2se/1.5.0/docs...nces.html#userNodeForPackage(java.lang.Class)>

I hadn't seen this before (where have I been?). Where does it store
stuff on a Linux system?

 

[Jason Cavett]

The default Sun implementation on Windows stores preferences in a node
under HKEY_CURRENT_USER, which is always writable by the current user
and is normally made part of the user's profile, whether local or
roaming.

So no, not really.

By "normally" do you mean that, assuming no problems, I can assume the
settings will be saved on a per-user basis?

 

[Thomas Fritsch]

I hadn't seen this before (where have I been?). Where does it store
stuff on a Linux system?

On my Linux I found it in file
$HOME/.java/.userprefs/my/package/prefs.xml

And (by the way) on Windows it is in registry section
HKEY_CURRENT_USER\Software\JavaSoft\prefs\my\package

 

[Thomas Fritsch]

On my Linux I found it in file
$HOME/.java/.userprefs/my/package/prefs.xml

$HOME/.java/.userPrefs/my/package/prefs.xml

And (by the way) on Windows it is in registry section
HKEY_CURRENT_USER\Software\JavaSoft\prefs\my\package

HKEY_CURRENT_USER\Software\JavaSoft\Prefs\my\package

Sorry for the 2 typos...

 

[Knute Johnson]

HKEY_CURRENT_USER\Software\JavaSoft\Prefs\my\package

Sorry for the 2 typos...

Thanks Thomas.

 

[Brandon McCombs]

By "normally" do you mean that, assuming no problems, I can assume the
settings will be saved on a per-user basis?

Yes because for one thing the registry hive where the data is accessible
for the current user is HKEY_CURRENT_USER (imagine that) so it would
have to be on a per user basis because there is only one current user
allowed with Windows XP. Plus, if you look into HKEY_USERS hive in the
registry it will list all the SIDs of the users who have logged into the
PC whose registry you are currently viewing. A user's registry data is
part of the users profile so it will follow them (stored in ntuser.dat
in every user's profile) and when they log in the HKEY_CURRENT_USER hive
is just a link to the real location under HKEY_USERS. It is possible
for permissions to be screwed up on HKEY_CURRENT_USER such that a user
can't retain settings (like Windows Explorer folder view preferences)
but normally each user can read/write to that location because they need
to.

I use the Preferences API in my program to store connection settings to
a remote server in the registry for each other based on a recommendation
I received from this group a few months ago. The API is so easy and
after I experimented with it I was able to implement my code very quickly.

 

[Jason Cavett]

Yes because for one thing the registry hive where the data is accessible
for the current user is HKEY_CURRENT_USER (imagine that) so it would
have to be on a per user basis because there is only one current user
allowed with Windows XP. Plus, if you look into HKEY_USERS hive in the
registry it will list all the SIDs of the users who have logged into the
PC whose registry you are currently viewing. A user's registry data is
part of the users profile so it will follow them (stored in ntuser.dat
in every user's profile) and when they log in the HKEY_CURRENT_USER hive
is just a link to the real location under HKEY_USERS. It is possible
for permissions to be screwed up on HKEY_CURRENT_USER such that a user
can't retain settings (like Windows Explorer folder view preferences)
but normally each user can read/write to that location because they need
to.

I use the Preferences API in my program to store connection settings to
a remote server in the registry for each other based on a recommendation
I received from this group a few months ago. The API is so easy and
after I experimented with it I was able to implement my code very quickly.- Hide quoted text -

- Show quoted text -

I just finished implementing Preferences for an application I'm
working on. Wow...haha...that was so painless I felt like I did
something wrong.

;-) Loving the Preferences.