DDevelopment & Design

SpringWeb + Hibernate + Database encoding problems – solved!

  • byRafal P
  • August 12, 2010
  • 2 minute read

Some time ago, I was investigating SmartClient (SmartGWT) and writting small app to connect via hibernate to MySQL database. During this tests I stuck with Polish locale problem. Such problems I’ve been facing not only this time, but many times in my career. Today, though it’s pretty easy, I will describe once for all how to solve the problem with web apps and Polish (but also any non english) encoding.

The first thing to be done is to set UTF-8 encodings in all web frontend files (*.html/*.jsp etc) by adding following code into tags:

Ok, this was easy and has nothing to do with database, but at least it makes sure, that localized characters will be displayed in proper way in the browser.

Second thing to do is to write filter which will set UTF-8 coding to requests and responses. It could look this:

public class ToukEncodingFilter extends OncePerRequestFilter {

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws ServletException, IOException {

        response.setCharacterEncoding("UTF-8");

        request.setCharacterEncoding("UTF-8");
        chain.doFilter(request, response);

    }

}

 

Now, to make this filter running, the following lines have to be add to web.xml file:

CharacterEncodingFilter 
pl.touk.filters.ToukEncodingFilter 
CharacterEncodingFilter 
/*

Ok. So we have now all in web layer prepared. Now, to make it work with DB, the hibernate connection have to be configured like this:

url=jdbc:mysql:///?useUnicode=true&characterEncoding=UTF-8

It can be also done via hibernate properties.

Of course I assume, that database has UTF-8 encoding. I won’t write about this, becouse it is pretty well written all over internet. Just a little tip: it is easier to set this before creating any table ;-)

Last, but the most important thing, is to set jvm encoding parameters to UTF-8 and desired locale. If You are using Tomcat It can be done by modifying CATALINA_OPTS variable (in init script) by adding following options:

-Dfile.encoding=UTF-8 -Duser.country=PL -Duser.language=pl

That’s all!

— Previous article

Apache HISE. Nowy element otwartego stosu aplikacji SOA.

Next article —

How to change theme in Ext-Gwt (GXT) application

You May Also Like
DDevelopment & Design

Grails session timeout without XML

This article shows clean, non hacky way of configuring featureful event listeners for Grails application servlet context. Feat. HttpSessionListener as a Spring bean example with session timeout depending on whether user account is premium or not.

Common approaches

Speaking of session timeout config in Grails, a default approach is to install templates with a command. This way we got direct access to web.xml file. Also more unnecessary files are created. Despite that unnecessary files are unnecessary, we should also remember some other common knowledge: XML is not for humans.

Another, a bit more hacky, way is to create mysterious scripts/_Events.groovy file. Inside of which, by using not less enigmatic closure: eventWebXmlEnd = { filename -> ... }, we can parse and hack into web.xml with a help of XmlSlurper.
Even though lot of Grails plugins do it similar way, still it’s not really straightforward, is it? Besides, where’s the IDE support? Hello!?

Examples of both above ways can be seen on StackOverflow.

Simpler and cleaner way

By adding just a single line to the already generated init closure we have it done:
class BootStrap {


    def init = { servletContext ->    

        servletContext.addListener(OurListenerClass)    

    }    

}

Allrighty, this is enough to avoid XML. Sweets are served after the main course though :)

Listener as a Spring bean

Let us assume we have a requirement. Set a longer session timeout for premium user account.
Users are authenticated upon session creation through SSO.

To easy meet the requirements just instantiate the CustomTimeoutSessionListener as Spring bean at resources.groovy. We also going to need some source of the user custom session timeout. Let say a ConfigService.
beans = {    

    customTimeoutSessionListener(CustomTimeoutSessionListener) {    

        configService = ref('configService')    

    }    

}

With such approach BootStrap.groovy has to by slightly modified. To keep control on listener instantation, instead of passing listener class type, Spring bean is injected by Grails and the instance passed:
class BootStrap {


    def customTimeoutSessionListener


    def init = { servletContext ->    

        servletContext.addListener(customTimeoutSessionListener)

    }    

}

An example CustomTimeoutSessionListener implementation can look like:
import javax.servlet.http.HttpSessionEvent    

import javax.servlet.http.HttpSessionListener    

import your.app.ConfigService    


class CustomTimeoutSessionListener implements HttpSessionListener {    


    ConfigService configService


    @Override    

    void sessionCreated(HttpSessionEvent httpSessionEvent) {    

        httpSessionEvent.session.maxInactiveInterval = configService.sessionTimeoutSeconds

    }    


    @Override    

    void sessionDestroyed(HttpSessionEvent httpSessionEvent) { /* nothing to implement */ }    

}
Having at hand all power of the Spring IoC this is surely a good place to load some persisted user’s account stuff into the session or to notify any other adequate bean about user presence.

Wait, what about the user context?

Honest answer is: that depends on your case. Yet here’s an example of getSessionTimeoutMinutes() implementation using Spring Security:
import org.springframework.security.core.context.SecurityContextHolder    


class ConfigService {


    static final int 3H = 3 * 60 * 60

    static final int QUARTER = 15 * 60


    int getSessionTimeoutSeconds() {    


        String username = SecurityContextHolder.context?.authentication?.principal    

        def account = Account.findByUsername(username)    


        return account?.premium ? 3H : QUARTER

    }    

}
This example is simplified. Does not contain much of defensive programming. Just an assumption that principal is already set and is a String - unique username. Thanks to Grails convention our ConfigService is transactional so the Account domain class can use GORM dynamic finder.
OK, config fetching implementation details are out of scope here anyway. You can get, load, fetch, obtain from wherever you like to. Domain persistence, principal object, role config, external file and so on...

Any gotchas?

There is one. When running grails test command, servletContext comes as some mocked class instance without addListener method. Thus we going to have a MissingMethodException when running tests :(

Solution is typical:
def init = { servletContext ->

    if (Environment.current != Environment.TEST) {    

        servletContext.addListener(customTimeoutSessionListener)    

    }    

}
An unnecessary obstacle if you ask me. Should I submit a Jira issue about that?

TL;DR

Just implement a HttpSessionListener. Create a Spring bean of the listener. Inject it into BootStrap.groovy and call servletContext.addListener(injectedListener).