I decided to return to Dropwizard after a very long affair with Spring. I quickly got the absolute barebones REST service built, and it runs without any problems.
Using Dropwizard 0.7.1 and Java 1.8, only POM entries are the dropwizard-core dependency and the maven compiler plugin to enforce Java 1.8, as recommended by the Dropwizard user manual
However, as soon as I try to add an Optional QueryParam to the basic controller, the application fails to start with the following error (cut for brevity):
INFO [2015-01-03 17:44:58,059] io.dropwizard.jersey.DropwizardResourceConfig: The following paths were found for the configured resources:
GET / (edge.dw.sample.controllers.IndexController)
ERROR [2015-01-03 17:44:58,158] com.sun.jersey.spi.inject.Errors: The following errors and warnings have been detected with resource and/or provider classes:
SEVERE: Missing dependency for method public java.lang.String edge.dw.sample.controllers.IndexController.index(java.util.Optional) at parameter at index 0
Exception in thread "main" javax.servlet.ServletException: com.sun.jersey.spi.container.servlet.ServletContainer-6c2ed0cd@330103b7==com.sun.jersey.spi.container.servlet.ServletContainer,1,false
The code for the controller is as follows:
@Path("/")
public class IndexController {
@GET
@Timed
public String index(@QueryParam("name") Optional<String> name) {
String saying = "Hi";
if(name != null && name.isPresent()) {
saying += " " + name.get();
}
return saying;
}
}
If I remove Optional from the mix, the application runs just fine. I replace the Optional-specific code with null checks and it works perfectly.
Am I missing something fundamental here? Both Google Guava Optional and java.util.Optional fail with the same error. (And yes, I did narrow it down to the Optional object)
A quick Google/SO search yielded nothing useful, but feel free to point me to a resource I may have missed
Thanks in advance!
Moments after posting this, I found that the issue was my use of Java 1.8. If using Java 1.8, I have to add the Java8Bundle to my app:
POM Entry:
<dependency>
<groupId>io.dropwizard.modules</groupId>
<artifactId>dropwizard-java8</artifactId>
<version>0.7.0-1</version>
</dependency>
And code in the Application class:
@Override
public void initialize(Bootstrap<SampleConfiguration> bootstrap) {
bootstrap.addBundle(new Java8Bundle());
}
See: https://github.com/dropwizard/dropwizard-java8
This enables both Google Guava Optional and java.util.Optional to work just fine.
If I revert to Java 1.7 and use the Google Guava Optional, it works just fine as well and I don't have to include the Java8Bundle. I'll opt for the Java8Bundle for now, though, as using Java8 features is lucrative for me :)
Cheers!
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