On base of the guide from this blog, Roll your own Auto Discovery with Jersey and HK2, I have the follow resource POJO:
@Path("Test")
public class TestResource {
@Inject
private TestService service;
@GET
@Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
public Set<Test> getTests() {
return service.getAllTests();
}
}
The TestService
:
@Contract
public interface TestService {
public Set<Test> getAllTests();
}
The TestServiceImpl
@Service
public class TestServiceImpl implements TestService {
@Override
public Set<Test> getAllTests() {
Set<Test> tests = new HashSet<>();
Test c = new Test();
c.setName("test");
tests.add(c);
return tests;
}
}
The Jersey dependency in pom.xml
is of version 2.25.1
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.glassfish.jersey</groupId>
<artifactId>jersey-bom</artifactId>
<version>${jersey.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>javax.ws.rs</groupId>
<artifactId>javax.ws.rs-api</artifactId>
<version>2.0</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet-core</artifactId>
<!-- use the following artifactId if you don't need servlet 2.x compatibility -->
<!-- artifactId>jersey-container-servlet</artifactId -->
</dependency>
<dependency>
<groupId>org.glassfish.jersey.bundles</groupId>
<artifactId>jaxrs-ri</artifactId>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-json-jackson</artifactId>
</dependency>
<dependency>
<groupId>org.glassfish.hk2</groupId>
<artifactId>hk2</artifactId>
<version>2.5.0-b36</version>
</dependency>
In order to make Jersey scan the @Service and @Contract classes automatically, I used the inhabitant-generator
plugin with version 2.5.0-b36:
<plugin>
<groupId>org.glassfish.hk2</groupId>
<artifactId>hk2-inhabitant-generator</artifactId>
<version>2.5.0-b36</version>
<executions>
<execution>
<goals>
<goal>generate-inhabitants</goal>
</goals>
</execution>
</executions>
</plugin>
There is the corresponding Feature
implementation:
public class AutoServiceDiscovery implements Feature {
@Override
public boolean configure(FeatureContext context) {
ServiceLocator locator = ServiceLocatorProvider.getServiceLocator(context);
DynamicConfigurationService dcs = locator.getService(DynamicConfigurationService.class);
Populator populator = dcs.getPopulator();
try {
populator.populate(new ClasspathDescriptorFileFinder(this.getClass().getClassLoader()),
new DuplicatePostProcessor());
} catch (IOException | MultiException ex) {
Logger.getLogger(this.getClass().getName()).log(Level.SEVERE, null, ex);
}
return true;
}
}
And it is indeeded registered through my ResourceConfig
class:
@ApplicationPath("/*")
public class ApplicationConfig extends ResourceConfig {
public ApplicationConfig() {
packages("resources");
register(new AutoServiceDiscovery());
}
}
However, I send request to the /test
, got the following error:
MultiException has 3 exceptions. They are:
1. org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for
injection at SystemInjecteeImpl(requiredType=TestService,parent=TestResource,qualifiers=
{},position=-1,optional=false,self=false,unqualified=null,1947073589)
2. java.lang.IllegalArgumentException: While attempting to resolve the dependencies of
rx.practice.ee.jaxrs.resources.TestResource errors were found
3. java.lang.IllegalStateException: Unable to perform operation: resolve on
rx.practice.ee.jaxrs.resources.TestResource
org.jvnet.hk2.internal.Collector.throwIfErrors(Collector.java:89)
org.jvnet.hk2.internal.ClazzCreator.resolveAllDependencies(ClazzCreator.java:250)
org.jvnet.hk2.internal.ClazzCreator.create(ClazzCreator.java:358)
org.jvnet.hk2.internal.SystemDescriptor.create(SystemDescriptor.java:487)
org.glassfish.jersey.process.internal.RequestScope.findOrCreate(RequestScope.java:162)
...
Question: Anyone knows why the @Service class cannot be injected? I am using Tomcat server
After a couple of days research on the source code of inhabitat-generator
, I figured out that in case of web application package,war
, the locator file is not generated in META-INF/hk2-locator
as demonstracted in the HK2 Inhabitant Generator office site in case of using jar
as deployment package. The source code of AbstractInhabitantsGeneratorMojo.java told that in case of war
, locator files are generated in hk2-locator
, and this is not mentioned in the HK2 Inhabitant Generator office site.
However, when constructing the ClasspathDescriptorFileFinder without the directory names argument in the bootstrap class, AutoServiceDiscovery
, it is only compatible with jar
as deployment package, meaning it is only finding files in META-INF/hk2-locator
.
So the better solution would be not to use inhabitant-generator
plugin but the metadata-generator
dependency, which is an annotation processor at compile time and, it is proved out-of-the-box.
If someone is persistent to using this plugin, he/she could create his/her own ClasspathDescriptorFileFinder
so that it is able to find locator files from hk2-locator
Last but not least, I also tried to use the inhabitants-generator
plugin's options to generate the locator files in hk2-locator
, but this seems to be next to impossible as well