依泽注射泽西2.0 [英] Dependency injection with Jersey 2.0

问题描述

从零开始，没有任何以前的泽西1.x知识，我很难理解如何在我的泽西2.0项目中设置依赖注入。

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.

我也明白HK2可以在泽西2.0，但我似乎找不到有助于泽西2.0整合的文档。

I also understand that HK2 is available in Jersey 2.0, but I cannot seem to find docs that help with Jersey 2.0 integration.

@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资源，但一旦添加了@Inject到MyService，该框架抛出一个异常：

I can get the container to start and serve up my resource, but as soon as I add @Inject to MyService, the framework throws an exception:

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)

我的启动项目在GitHub可用： https：// g ithub.com/donaldjarmstrong/jaxrs

推荐答案

您需要定义一个 AbstractBinder 并注册到您的JAX-RS应用程序。绑定器指定依赖注入应该如何创建你的类。

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);
    }
}

当 @Inject 在 MyService.class 的参数或字段中检测到，它使用类 MyService 。要使用此绑定器，需要向JAX-RS应用程序注册。在 web.xml 中，定义一个JAX-RS应用程序，如下所示：

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>

实现 MyApplication class init-param ）。

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");
    }
}

指定依赖注入的绑定器注册在该类，我们还使用 packages（） MyResource ） $ c>方法调用。

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.

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