Dependency injection with Jersey 2.0

Question

Starting from scratch without any previous Jersey 1.x knowledge, I\'m having a hard time understanding how to setup dependency injection in my Jersey 2.0 project.

Answer 1

First just to answer a comment in the accepts answer.

"What does bind do? What if I have an interface and an implementation?"

It simply reads bind( implementation ).to( contract ). You can alternative chain .in( scope ). Default scope of PerLookup. So if you want a singleton, you can

bind( implementation ).to( contract ).in( Singleton.class );

There's also a RequestScoped available

Also, instead of bind(Class).to(Class), you can also bind(Instance).to(Class), which will be automatically be a singleton.

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Adding to the accepted answer

For those trying to figure out how to register your AbstractBinder implementation in your web.xml (i.e. you're not using a ResourceConfig), it seems the binder won't be discovered through package scanning, i.e.

org.glassfish.jersey.servlet.ServletContainer

    jersey.config.server.provider.packages
    
        your.packages.to.scan
    

Or this either

    jersey.config.server.provider.classnames
    
        com.foo.YourBinderImpl
    

To get it to work, I had to implement a Feature:

import javax.ws.rs.core.Feature;
import javax.ws.rs.core.FeatureContext;
import javax.ws.rs.ext.Provider;

@Provider
public class Hk2Feature implements Feature {

    @Override
    public boolean configure(FeatureContext context) {
        context.register(new AppBinder());
        return true;
    }
}

The @Provider annotation should allow the Feature to be picked up by the package scanning. Or without package scanning, you can explicitly register the Feature in the web.xml

    Jersey Web Application
    org.glassfish.jersey.servlet.ServletContainer
    
        jersey.config.server.provider.classnames
        
            com.foo.Hk2Feature
        
    
    ...
    1

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See Also:

• Custom Method Parameter Injection with Jersey
• How to inject an object into jersey request context?
• How do I properly configure an EntityManager in a jersey / hk2 application?
• Request Scoped Injection into Singletons

and for general information from the Jersey documentation

• Custom Injection and Lifecycle Management

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UPDATE

Factories

Aside from the basic binding in the accepted answer, you also have factories, where you can have more complex creation logic, and also have access to request context information. For example

public class MyServiceFactory implements Factory {
    @Context
    private HttpHeaders headers;

    @Override
    public MyService provide() {
        return new MyService(headers.getHeaderString("X-Header"));
    }

    @Override
    public void dispose(MyService service) { /* noop */ }
}

register(new AbstractBinder() {
    @Override
    public void configure() {
        bindFactory(MyServiceFactory.class).to(MyService.class)
                .in(RequestScoped.class);
    }
});

Then you can inject MyService into your resource class.