Lombok looks interesting. Groovy makes this sort of code very
palatable too, instead of:
> @Cleanup PreparedStatement ps = connection.prepareStatement
> (sql);
> @Cleanup ResultSet resultSet = ps.executeQuery();
> while (resultSet.next()) {
> // stuff
> }
You would do:
sql.eachRow(sql) { /* stuff */ }
On Tue, Aug 18, 2009 at 5:00 PM, Reinier Zwitserloot<reini...@gmail.com> wrote:
>
> public void handleWebRequest(String target, Request req, Response res)
> throws Exception {
> �...@cleanup("release") Db db = worker.getDb();
> db.doWhatever();
> }
>
>
>
> couldn't be simpler, really. @Cleanup is from project lombok, and it
> ensures the db is released even if this method errors out. Note how I
> just toss a 'throws Exception' on there. This is a servlet; it's
> effectively an entire application all by itself. That kind of broad
> context is allowed to throw whatever the heck it wants. The code that
> calls into this code catches throwable, because if a servlet errors
> out, even with something drastic like, say, an InternalError, it
> should not take the whole webserver down with it. The code that
> catches this does some sorting work on the exception in question, and
> targets a different log file if it seems particularly nasty (such as
> out of memory, internalerror, virtual machine error, and a few
> others), but that's really an implementation detail. The point is: The
> gazillion different instances of 'handleWebRequest' are as simple as I
> could make them.
>
> NB: The db object isn't passed in primarily because not all these
> handlers need one, and the db engine is an entirely separate module,
> so I'd rather avoid adding a dependency there. If I didn't have
> lombok, I would make Db 'lazy' and grab a connection only when a
> request happens, so that you don't have to try/finally this stuff, and
> pass a Db object into the handleWebRequest call.
>
> For you JDBC users, I suggest you go play with projectlombok.org.
> Here's Christian Catchpole's code sample without lombok:
>
> PreparedStatement ps = connection.prepareStatement(sql);
> try {
> ResultSet resultSet = ps.executeQuery();
> try {
> while (resultSet.next()) {
> // stuff
> }
> } finally {
> resultSet.close();
> }
> } finally {
> ps.close();
> }
>
> and here's the same thing with lombok:
>
> �...@cleanup PreparedStatement ps = connection.prepareStatement
> (sql);
> �...@cleanup ResultSet resultSet = ps.executeQuery();
> while (resultSet.next()) {
> // stuff
> }
>
>
> If you have a need to handle SQLExceptions locally (I would like to
> state again that if you are forced to do this, your framework sucks
> and you should fix it!), it would turn into:
>
> try {
> �...@cleanup PreparedStatement ps = connection.prepareStatement
> (sql);
> �...@cleanup ResultSet resultSet = ps.executeQuery();
> while (resultSet.next()) {
> // stuff
> }
> } catch ( SQLException e ) {
> //What are ya gonna do now?
> }
>
>
> rule of thumb: If you can't do anything useful in your catch block
> other than log and/or wrap it, you're doing it wrong.
>
>
> And to the genius who mentioned beep(): Whoa. Did not know about it.
> Evil! Muhahaha!
>
> On Aug 18, 3:29 am, phil swenson <phil.swen...@gmail.com> wrote:
>> I'm happy to see all the runtime exception advocates on here.
>> Definitely not the mainstream view. Smart crowd :)
>>
>> I would love to see some example of how you guys write JDBC code.
>> JDBC code is usually the most heinous of all with all the SQLException
>> and resource handling crap you have to do.
>>
>> Please post a snippet :)
>>
>> On Aug 17, 6:47 pm, Michael Neale <michael.ne...@gmail.com> wrote:
>>
>>
>>
>> > The only sane way is this:
>>
>> > try {
>>
>> > .. your code here
>>
>> > } catch (Throwable t) {
>>
>> > for (int i =0; i< 1000; i++)
>> > java.awt.Toolkit.beep();
>> > System.exit(-1);
>>
>> > }
>>
>> > Sometimes can use a Runtime.exec to delete the home directory for good
>> > measure, but that means platform specific code.
>>
>> > On Aug 18, 8:58 am, Casper Bang <casper.b...@gmail.com> wrote:
>>
>> > > For that we have Runtime().getRuntime().addShutdownHook() no? That's
>> > > what I used anyway with JSR-296, where Hans Muller had hardwired the
>> > > System.exit() call in the framework.
>>
>> > > /Casper
>>
>> > > On 17 Aug., 23:11, Peter Becker <peter.becker...@gmail.com> wrote:
>>
>> > > > Jess Holle wrote:
>> > > > > Peter Becker wrote:
>>
>> > > > >> While I agree that you can have shared state, the scenario I had
>> > > > >> was a
>> > > > >> clean worker: some data goes in before the thread gets started,
>> > > > >> other
>> > > > >> data comes out at the end.
>>
>> > > > >> System.exit is a bad idea generally since you don't really know who
>> > > > >> is
>> > > > >> going to use your code in the future. If you call System.exit in
>> > > > >> your
>> > > > >> average Tomcat installation you'll probably take it down with you. I
>> > > > >> tend to restrict the System.exit calls to main(..) methods.
>>
>> > > > > Low-level code shouldn't be catching VirtualMachineError -- it should
>> > > > > always re-throw it.
>>
>> > > > I agree. But between the likelihood of this error being raised and the
>> > > > damage done if you catch it when you shouldn't the risk seems quite
>> > > > acceptable. Again: it is highly dependent on what your application is,
>> > > > I
>> > > > would certainly not recommend this for a mission or even life critical
>> > > > section of code.
>>
>> > > > > Only top-level thread handlers should catch these errors and call
>> > > > > System.exit().
>>
>> > > > And what happens to other threads? If you call System.exit you should
>> > > > have global knowledge of all application threads and their current
>> > > > state. Even in the presence of a VirtualMachineError it is probably
>> > > > better to try a clean shutdown. Calling System.exit could leave a lot
>> > > > of
>> > > > things in inconsistent state that will be hard to recover from. Are all
>> > > > your system's boundaries transactional?
>>
>> > > > Peter
> >
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "The
Java Posse" group.
To post to this group, send email to javaposse@googlegroups.com
To unsubscribe from this group, send email to
javaposse+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/javaposse?hl=en
-~----------~----~----~----~------~----~------~--~---
