java 如何注入接口实现？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/25982947/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to inject an interface implementation?
提问by flash
I have the following interface
我有以下界面
public interface IMyMapper<T> {}
and the implementation
和实施
public class MyMapper implements IMyMapper<MyClazz> {}
Now I want to inject the class MyMapperinto a Stateless bean:
现在我想将该类MyMapper注入到无状态 bean 中：
@Stateless
public class MyService {
@Inject
MyMapper mapper; //<-- does not work
@Inject
IMyMapper<MyClazz> mapper; //<-- also does not work
}
My problem is that the injection does not work. I get an exception:
我的问题是注射不起作用。我得到一个例外：
org.jboss.weld.exceptions.DeploymentException: WELD-001408: Unsatisfied dependencies for type MyMapper with qualifiers @Default
at injection point [BackedAnnotatedField] @Inject mypackage.MyService.mapper
at mypackage.MyService.mapper(MyService.java:0)
at org.jboss.weld.bootstrap.Validator.validateInjectionPointForDeploymentProblems(Validator.java:370)
at org.jboss.weld.bootstrap.Validator.validateInjectionPoint(Validator.java:291)
at org.jboss.weld.bootstrap.Validator.validateGeneralBean(Validator.java:134)
at org.jboss.weld.bootstrap.Validator.validateRIBean(Validator.java:165)
at org.jboss.weld.bootstrap.Validator.validateBean(Validator.java:529)
at org.jboss.weld.bootstrap.Validator.validateBeans(Validator.java:515)
at org.jboss.weld.bootstrap.Validator.validateDeployment(Validator.java:490)
at org.jboss.weld.bootstrap.WeldStartup.validateBeans(WeldStartup.java:419)
at org.jboss.weld.bootstrap.WeldBootstrap.validateBeans(WeldBootstrap.java:90)
at org.glassfish.weld.WeldDeployer.event(WeldDeployer.java:225)
at org.glassfish.kernel.event.EventsImpl.send(EventsImpl.java:131)
at org.glassfish.internal.data.ApplicationInfo.load(ApplicationInfo.java:328)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:496)
at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:219)
at org.glassfish.deployment.admin.DeployCommand.execute(DeployCommand.java:491)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.run(CommandRunnerImpl.java:539)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.run(CommandRunnerImpl.java:535)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:360)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.execute(CommandRunnerImpl.java:534)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.run(CommandRunnerImpl.java:565)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.run(CommandRunnerImpl.java:557)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:360)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:556)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1464)
at com.sun.enterprise.v3.admin.CommandRunnerImpl.access00(CommandRunnerImpl.java:109)
at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1846)
at org.glassfish.deployment.autodeploy.AutoOperation.run(AutoOperation.java:164)
at org.glassfish.deployment.autodeploy.AutoDeployer.deploy(AutoDeployer.java:597)
at org.glassfish.deployment.autodeploy.AutoDeployer.deployAll(AutoDeployer.java:484)
at org.glassfish.deployment.autodeploy.AutoDeployer.run(AutoDeployer.java:412)
at org.glassfish.deployment.autodeploy.AutoDeployer.run(AutoDeployer.java:403)
at org.glassfish.deployment.autodeploy.AutoDeployService.run(AutoDeployService.java:233)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
]]
How can I solve this?
我该如何解决这个问题？
回答by Antoine Sabot-Durand
You probably are in annotatedbean discovery mode (the default mode in CDI 1.1+), that's why your class MyMapperis not considered as a bean class. In this mode, to be discovered bean class should have a bean defining annotation. @Statelessis a bean defining annotation so your EJB is also a CDI bean but its injection point cannot be satisfied because MyMapperwasn't discovered a bean class.
您可能处于annotatedbean 发现模式（CDI 1.1+ 中的默认模式），这就是为什么您的类MyMapper不被视为 bean 类的原因。在这种模式下，要被发现的 bean 类应该有一个bean 定义注解。@Stateless是一个定义注解的 bean，所以你的 EJB 也是一个 CDI bean，但它的注入点不能满足，因为MyMapper没有发现 bean 类。
To make your code work try to put @Dependenton your class
为了让你的代码工作，试着穿上@Dependent你的课
@Dependent
public class MyMapper implements IMyMapper<MyClazz> {}
Alternatively you can change the discovery mode of your project as stated in the specification.
或者，您可以按照规范中的说明更改项目的发现模式。
