问题
从头开始没有任何以前的Jersey 1.x知识,我很难理解如何在我的Jersey 2.0项目中设置依赖注入。
我也明白HK2可用于Jersey 2.0,但我似乎无法找到有助于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");
}
}
的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,但是只要我将@Inject添加到MyService,框架就会抛出异常:
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)
我的初学者项目可在GitHub获得:https://github.com/donaldjarmstrong/jaxrs
#1 热门回答(92 赞)
你需要定义一个AbstractBinder
并在JAX-RS应用程序中注册它。绑定器指定依赖注入应如何创建类。
public class MyApplicationBinder extends AbstractBinder {
@Override
protected void configure() {
bind(MyService.class).to(MyService.class);
}
}
在类型为MyService.class
的参数或字段上检测到@Inject
时,使用classMyService
进行实例化。要使用此绑定器,需要在JAX-RS应用程序中注册。在yourweb.xml
中,定义一个这样的JAX-RS应用程序:
<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(在init-param
中指定)。
public class MyApplication extends ResourceConfig {
public MyApplication() {
register(new MyApplicationBinder());
packages(true, "com.mypackage.rest");
}
}
指定依赖项注入的绑定程序在类的构造函数中注册,我们还使用packages()
方法调用告诉应用程序在何处查找REST资源(在你的情况下,MyResource
)。
#2 热门回答(44 赞)
首先只是回答接受答案中的评论。
"绑定做什么?如果我有接口和实现怎么办?"
它简单地读取bind( implementation ).to( contract )
。你可以选择chain.in( scope )
。默认范围为PerLookup
。所以,如果你想要一个单例,你可以
bind( implementation ).to( contract ).in( Singleton.class );
还有aRequestScoped
可用
此外,你还可以使用bind(Instance).to(Class)
代替4331202501,它将自动成为单例。
对于那些试图弄清楚如何在你的web.xml中注册你的AbstractBinder
实现的人(即你没有使用aResourceConfig
),似乎不会通过包扫描发现活页夹,即
<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>
或者这个
<init-param>
<param-name>jersey.config.server.provider.classnames</param-name>
<param-value>
com.foo.YourBinderImpl
</param-value>
</init-param>
为了让它工作,我必须实现aFeature
:
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;
}
}
@Provider
注释应该允许Feature
被包扫描拾取。或者,如果没有包扫描,你可以在web.xml
中明确注册Feature
<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>
另请参见:-使用Jersey的自定义方法参数注入
- 如何将对象注入泽西请求上下文?
- 如何在jersey / hk2应用程序中正确配置EntityManager?
- 请求将单一注射注入单例
以及来自Jersey文档的一般信息
- 自定义注入和生命周期管理
##更新
###工厂
除了已接受答案中的基本绑定外,你还拥有工厂,你可以在其中拥有更复杂的创建逻辑,还可以访问请求上下文信息。例如
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);
}
});
然后你可以将MyService
注入你的资源类。
#3 热门回答(11 赞)
选定的答案可以追溯到前一段时间。在自定义HK2活页夹中声明每个绑定是不切实际的。我正在使用Tomcat,我只需添加一个依赖项。尽管它是专为Glassfish设计的,但它完全适合其他容器。
<dependency>
<groupId>org.glassfish.jersey.containers.glassfish</groupId>
<artifactId>jersey-gf-cdi</artifactId>
<version>${jersey.version}</version>
</dependency>
确保你的容器也已正确配置(see the documentation)。