Guice - Jersey - Servlet binding

问题:

I recently switched to two phase injection and this has created an error in my servlet binding. I am currently toggling between two error modes and not sure which direction is best to pursue.

The first error I encountered was:

com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes.

My servlet module looked like this:

public class MyServletModule extends JerseyServletModule {
    @Override
    protected void configureServlets() {
        bind(MyServlet.class).asEagerSingleton();

        serve("/*").with(GuiceContainer.class);
    }
}

I was able to remove this error by explicitly providing the com.sun.jersey.config.property.packages parameter.

public class MyServletModule extends JerseyServletModule {

    @Override
    protected void configureServlets() {
        bind(MyServlet.class).asEagerSingleton();

        Map<String,String> parameters = new HashMap<String, String>();
        parameters.put(PackagesResourceConfig.PROPERTY_PACKAGES, MyServlet.class.getPackage().getName());
        serve("/*").with(GuiceContainer.class, parameters);
    }
}

But when I do this, Guice attempts a Just in Time binding which does not respect the @Inject on my servlet constructor.

com.google.inject.ConfigurationException: Guice configuration errors:

1) Unable to create binding for MyServlet. It was already configured on one or more child injectors or private modules bound at MyServletModule.configureServlets(MyServletModule.java:44) If it was in a PrivateModule, did you forget to expose the binding? while locating MyServlet

1 error at com.google.inject.internal.InjectorImpl.getBinding(InjectorImpl.java:150)

My servlet has an @Inject constructor who's arguments cannot be bound just in time. After debugging into InjectorImpl, I believe this is the reason that things fail when I use PROPERTY_PACKAGES.

I'm just not sure if using PROPERTY_PACKAGES is correct and I need to fix some bindings? Or if that is the wrong direction and I need to fix the original ResourceConfig error in a different way.

Help or a push in the right direction is appreciated.

回答1:

I was able to bind Jersey resources to Guice without using the bind-parameters (without explicitly providing the com.sun.jersey.config.property.packages parameter), by binding resources separately

public class BindJerseyResources extends ServletModule {

    @Override
    protected void configureServlets() {
        // excplictly bind GuiceContainer before binding Jersey resources
        // otherwise resource won't be available for GuiceContainer
        // when using two-phased injection
        bind(GuiceContainer.class);

        // bind Jersey resources
        PackagesResourceConfig resourceConfig = new PackagesResourceConfig("jersey.resources.package");
        for (Class<?> resource : resourceConfig.getClasses()) {
            bind(resource);
        }

        // Serve resources with Jerseys GuiceContainer
        serve("/*").with(GuiceContainer.class);
    }
}

The resources are like following

@Path("/")
@RequestScoped
public class Resource {

    private Storage storage;

    @Inject
    public Resource(Storage storage) {
        this.storage = storage;
    }

    @GET
    @Path("get/{name}")
    @Produces(MediaType.TEXT_PLAIN)
    public String getGuid(@PathParam("name") String name) {
        return storage.get(name);
    }
}

Maybe this helps you to avoid the latter problematic binding.

---

Updated the answer to work with two-phased injection.

回答2:

Java Part

import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Singleton;
import com.google.inject.persist.jpa.JpaPersistModule;
import com.google.inject.servlet.GuiceServletContextListener;
import com.sun.jersey.guice.JerseyServletModule;
import com.sun.jersey.guice.spi.container.servlet.GuiceContainer;
import com.sun.jersey.spi.container.servlet.ServletContainer;
import com.thjug.apipublic.Echo;

public class ServletContextListener extends GuiceServletContextListener {

    @Override
    protected Injector getInjector() {
        final Injector injector = Guice.createInjector(new JerseyServletModule() {
            @Override
            protected void configureServlets() {
                bind(Echo.class);
                bind(ServletContainer.class).in(Singleton.class);
                serve("/*").with(GuiceContainer.class);
            }
        }, new JpaPersistModule("dbUnit"), new LoggingModule());

        injector.getInstance(JPAInitializer.class);
        return injector;
    }
}

web.xml

    <distributable />

    <display-name>API</display-name>

    <filter>
            <filter-name>guiceFilter</filter-name>
            <filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
    </filter>
    <filter-mapping>
            <filter-name>guiceFilter</filter-name>
            <url-pattern>/*</url-pattern>
    </filter-mapping>

    <listener>
            <description>Guice Initiate</description>
            <listener-class>com.thjug.base.ServletContextListener</listener-class>
    </listener>

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回答3:

Here's an article on how to do the binding (including full source code): implementing-distributed-counter