My $0.02 which are somewhat not guice related: I would assume that in production at least you are using a connection pool for which the cost of "opening a connection" is mitigated. When you do this, you can effectively open/close connections on a per-statement or per-transaction basis without the performance cost that would normally imply, instead of using request scoped connection.
One thing your filter does which is convenient, though, is ensure that your connections are "closed" (i.e., returned to the connection pool) without having to rely on remembering to do so. A useful library that provides an alternative is JDBI: https://github.com/brianm/jdbi With this you can inject a @Singleton instance of DBI and use it thusly: dbi.withHandle( new HandleCallback<Void>() { // the DBI instance will open a connection, wrap in a Handle object and pass // it to the callback: public Void withHandle(Handle handle) throws Exception { // Do your SQL operations using the handle return null; } // Handle is closed by the DBI before returning. }); It's slightly more code than you'd normally need when using a Connection object directly, but you can hide all that within a DAO wrapper object of some kind and inject that instead. YMMV, Christopher 2011/1/21 Willi Schönborn <[email protected]>: > I successfully used custom scope implementations which check for > instances which require proper destruction (Closeables, @PreDestroy, ...). > This requires of course some kind of a strictly defined exit point. > > On 21/01/11 21:49, cowwoc wrote: >> >> Good point. Is there a way to check if a Connection has already been >> instantiated? >> >> Also, is there a cleaner way of passing an Injector to >> ConnectionFilter? Right now I am depending upon the fact that >> GuiceServletContextFilter sets an attribute with the name >> "Injector.class.getName()". This is an implementation detail that may change >> in the future. Is there a way for me to pass an Injector from >> GuiceServletContextFilter as a filter parameter? I saw thought of passing >> parameters using: >> >> filter("/*").through(ConnectionFilter.class, param); >> >> but the Injector hasn't been instantiated at that point. >> >> Thanks, >> Gili >> >> On 21/01/2011 3:38 PM, Willi Schönborn wrote: >>> >>> You should be aware that this might create and open >>> a jdbc connection just to close it right away. >>> >>> On 21/01/11 21:36, cowwoc wrote: >>>> >>>> Hi, >>>> >>>> Following up on this earlier discussion: >>>> >>>> http://groups.google.com/group/google-guice/browse_frm/thread/7252f908ef00638a/9a59803c16a9583e?lnk=gst&q=clean+%40requestscoped#9a59803c16a9583e >>>> >>>> What is the best way to clean up a @RequestScoped JDBC connection? Am >>>> I supposed to register a second ServletFilter after GuiceFilter (shown >>>> below) or is there an easier way? >>>> >>>> public class ConnectionFilter implements Filter >>>> { >>>> private ServletContext context; >>>> >>>> @Override >>>> public void init(FilterConfig filterConfig) throws ServletException >>>> { >>>> this.context = filterConfig.getServletContext(); >>>> } >>>> >>>> @Override >>>> public void doFilter(ServletRequest servletRequest, ServletResponse >>>> servletResponse, >>>> FilterChain chain) >>>> throws IOException, ServletException >>>> { >>>> Injector injector = (Injector) >>>> context.getAttribute(Injector.class.getName()); >>>> Connection connection = injector.getInstance(Connection.class); >>>> >>>> try >>>> { >>>> chain.doFilter(servletRequest, servletResponse); >>>> } >>>> finally >>>> { >>>> connection.close(); >>>> } >>>> } >>>> >>>> @Override >>>> public void destroy() >>>> { >>>> } >>>> } >>>> >>>> >>>> Thanks, >>>> Gili >>>> >>> >> > > -- > You received this message because you are subscribed to the Google Groups > "google-guice" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/google-guice?hl=en. > > -- You received this message because you are subscribed to the Google Groups "google-guice" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-guice?hl=en.
