新泽西2.0版本的依赖注入

在没有任何新泽西1. x 知识的情况下从头开始,我很难理解如何在我的新泽西2.0项目中设置依赖注入。

我也知道 HK2在 Jersey 2.0中是可用的,但是我似乎找不到有助于 Jersey 2.0集成的文档。

@ManagedBean
@Path("myresource")
public class MyResource {


@Inject
MyService myService;


/**
* Method handling HTTP GET requests. The returned object will be sent
* to the client as "text/plain" media type.
*
* @return String that will be returned as a text/plain response.
*/
@GET
@Produces(MediaType.APPLICATION_JSON)
@Path("/getit")
public String getIt() {
return "Got it {" + myService + "}";
}
}


@Resource
@ManagedBean
public class MyService {
void serviceCall() {
System.out.print("Service calls");
}
}

Pom.xml

<properties>
<jersey.version>2.0-rc1</jersey.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>


<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>org.glassfish.jersey.core</groupId>
<artifactId>jersey-common</artifactId>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.core</groupId>
<artifactId>jersey-server</artifactId>
</dependency>
<dependency>
<groupId>org.glassfish.jersey</groupId>
<artifactId>jax-rs-ri</artifactId>
</dependency>
</dependencies>

我可以让容器启动并提供我的资源,但是一旦我将@Inject 添加到 MyService,框架就会抛出一个异常:

SEVERE: Servlet.service() for servlet [com.noip.MyApplication] in context with path [/jaxrs] threw exception [A MultiException has 3 exceptions.  They are:
1. org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for injection at Injectee(requiredType=MyService,parent=MyResource,qualifiers={}),position=-1,optional=false,self=false,unqualified=null,1039471128)
2. java.lang.IllegalArgumentException: While attempting to resolve the dependencies of com.noip.MyResource errors were found
3. java.lang.IllegalStateException: Unable to perform operation: resolve on com.noip.MyResource
] with root cause
org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for injection at Injectee(requiredType=MyService,parent=MyResource,qualifiers={}),position=-1,optional=false,self=false,unqualified=null,1039471128)
at org.jvnet.hk2.internal.ThreeThirtyResolver.resolve(ThreeThirtyResolver.java:74)


我的启动项目可以在 GitHub 上找到: < a href = “ https://GitHub.com/donaldjarmstrong/jaxrs”rel = “ norefrer”> https://GitHub.com/donaldjarmstrong/jaxrs

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You need to define an AbstractBinder and register it in your JAX-RS application. The binder specifies how the dependency injection should create your classes.

public class MyApplicationBinder extends AbstractBinder {
@Override
protected void configure() {
bind(MyService.class).to(MyService.class);
}
}

When @Inject is detected on a parameter or field of type MyService.class it is instantiated using the class MyService. To use this binder, it need to be registered with the JAX-RS application. In your web.xml, define a JAX-RS application like this:

<servlet>
<servlet-name>MyApplication</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>javax.ws.rs.Application</param-name>
<param-value>com.mypackage.MyApplication</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>MyApplication</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>

Implement the MyApplication class (specified above in the init-param).

public class MyApplication extends ResourceConfig {
public MyApplication() {
register(new MyApplicationBinder());
packages(true, "com.mypackage.rest");
}
}

The binder specifying dependency injection is registered in the constructor of the class, and we also tell the application where to find the REST resources (in your case, MyResource) using the packages() method call.

Oracle recommends to add the @Path annotation to all types to be injected when combining JAX-RS with CDI: http://docs.oracle.com/javaee/7/tutorial/jaxrs-advanced004.htm Though this is far from perfect (e.g. you will get warning from Jersey on startup), I decided to take this route, which saves me from maintaining all supported types within a binder.

Example:

@Singleton
@Path("singleton-configuration-service")
public class ConfigurationService {
..
}


@Path("my-path")
class MyProvider {
@Inject ConfigurationService _configuration;


@GET
public Object get() {..}
}

If you prefer to use Guice and you don't want to declare all the bindings, you can also try this adapter:

guice-bridge-jit-injector

The selected answer dates from a while back. It is not practical to declare every binding in a custom HK2 binder. I'm using Tomcat and I just had to add one dependency. Even though it was designed for Glassfish it fits perfectly into other containers.

   <dependency>
<groupId>org.glassfish.jersey.containers.glassfish</groupId>
<artifactId>jersey-gf-cdi</artifactId>
<version>${jersey.version}</version>
</dependency>

Make sure your container is properly configured too (see the documentation).

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.


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.

<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>jersey.config.server.provider.packages</param-name>
<param-value>
your.packages.to.scan
</param-value>
</init-param>

Or this either

<init-param>
<param-name>jersey.config.server.provider.classnames</param-name>
<param-value>
com.foo.YourBinderImpl
</param-value>
</init-param>

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

<servlet>
<servlet-name>Jersey Web Application</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>jersey.config.server.provider.classnames</param-name>
<param-value>
com.foo.Hk2Feature
</param-value>
</init-param>
...
<load-on-startup>1</load-on-startup>
</servlet>

See Also:

and for general information from the Jersey documentation


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<MyService> {
@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.

Late but I hope this helps someone.

I have my JAX RS defined like this:

@Path("/examplepath")
@RequestScoped //this make the diference
public class ExampleResource {

Then, in my code finally I can inject:

@Inject
SomeManagedBean bean;

In my case, the SomeManagedBean is an ApplicationScoped bean.

Hope this helps to anyone.

For me it works without the AbstractBinder if I include the following dependencies in my web application (running on Tomcat 8.5, Jersey 2.27):

<dependency>
<groupId>javax.ws.rs</groupId>
<artifactId>javax.ws.rs-api</artifactId>
<version>2.1</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
<version>${jersey-version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.ext.cdi</groupId>
<artifactId>jersey-cdi1x</artifactId>
<version>${jersey-version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.inject</groupId>
<artifactId>jersey-hk2</artifactId>
<version>${jersey-version}</version>
</dependency>

It works with CDI 1.2 / CDI 2.0 for me (using Weld 2 / 3 respectively).

Dependency required for jersey restful service and Tomcat is the server. where ${jersey.version} is 2.29.1

    <dependency>
<groupId>javax.enterprise</groupId>
<artifactId>cdi-api</artifactId>
<version>2.0.SP1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.core</groupId>
<artifactId>jersey-server</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
<version>${jersey.version}</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.inject</groupId>
<artifactId>jersey-hk2</artifactId>
<version>${jersey.version}</version>
</dependency>

The basic code will be as follows:

@RequestScoped
@Path("test")
public class RESTEndpoint {


@GET
public String getMessage() {