@InterceptorBinding / CDI/ EJB 3.2 - 注入问题

Question

我的开发环境是：WildFly 8.1、CDI、EJB 3.2、JDK1.7。应用程序打包为一个 ear 存档（一个 ejb + 一个 war），因为将来它可能会有其他网络模块。

我正在努力处理在我的 EJB 无状态 bean 中使用的自定义 @InterceptorBinding 类型。

@Inherited
@InterceptorBinding
@Target({ TYPE, METHOD })
@Retention(RUNTIME)
@Documented
public @interface DetectIntegrityConstraintsViolation {
}

@javax.annotation.ManagedBean  // make it a CDI bean. @Interceptor itself should be enough, but WildFly 8.1 seems to have a bug, since it doesn't work without this line.
@Interceptor
@DetectIntegrityConstraintsViolation
public class ReferentialIntegrityConstraintViolationInterceptor {

    @PersistenceContext
    private EntityManager em;

    @Resource
    private SessionContext sessionContext;

    // ....
 }

beans.xml:

<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_1_1.xsd"
       version="1.1" bean-discovery-mode="annotated">

  <interceptors>
    <class>com.xxx.ejb.ReferentialIntegrityConstraintViolationInterceptor</class>
  </interceptors>
</beans>

当我通过 REST 服务调用我的 EJB 方法时，我得到 Error injecting resource into CDI managed bean:

javax.naming.NameNotFoundException: Caused by java.lang.IllegalStateException: JBAS011048: Failed to construct component instance  Caused by: java.lang.IllegalArgumentException: JBAS016081: Error injecting resource into CDI managed bean.
Can't find a resource named java:comp/env/com.xxx.ejb.ReferentialIntegrityConstraintViolationInterceptor/sessionContext defined on private javax.ejb.SessionContext com.xxx.ejb.ReferentialIntegrityConstraintViolationInterceptor.sessionContext   at org.jboss.as.weld.services.bootstrap.WeldResourceInjectionServices.resolveResource(WeldResourceInjectionServices.java:188) [wildfly-weld-8.1.0.Final.jar:8.1.0.Final]

所以在黑暗中行走，我转向了 ResourceLookup 方法：

@ManagedBean
@Interceptor
@DetectIntegrityConstraintsViolation
public class ReferentialIntegrityConstraintViolationInterceptor {

    @PersistenceContext
    private EntityManager em;

    private SessionContext sessionContext;

    @PostConstruct
    public void init(InvocationContext ctx) {
        try {
            InitialContext ic = new InitialContext();
            this.sessionContext = (SessionContext)ic.lookup("java:comp/EJBContext");
        } catch (NamingException ex) {
            throw new RuntimeException(ex.getMessage());
        }
    }

    // .....
}

然后注入开始工作，但是我得到了一个新的错误：

Caused by: org.jboss.weld.exceptions.DefinitionException: WELD-000619: An interceptor for lifecycle callbacks Interceptor [class com.xxx.ejb.ReferentialIntegrityConstraintViolationInterceptor intercepts @DetectIntegrityConstraintsViolation] declares and interceptor binding interface com.xxx.ejb.DetectIntegrityConstraintsViolation with METHOD as its @Target.

因此，当从 DetectIntegrityConstraintsViolation 中删除一个 METHOD 目标时：

@Inherited
@InterceptorBinding
@Target({ TYPE /*, METHOD*/ }) // CRUCIAL
@Retention(RUNTIME)
@Documented
public @interface DetectIntegrityConstraintsViolation {
}

然后开始工作。但是为什么？？
为什么我不能在方法上放置注释？有人知道吗？

顺便说一句：更奇怪的是，当我没有使用 @InterceptorBinding，而是普通的旧版本时：

@Override
// @DetectIntegrityConstraintsViolation
@Interceptors(ReferentialIntegrityConstraintViolationInterceptor.class)
public User updateUser(final User user) {
    // ...
}

拦截器即使在方法级别也能完美运行。

我发现 EJB 和 Weld 非常适合使用 awkward...

Answer 1

CDI spec:

中描述了您的一条错误消息

An interceptor for lifecycle callbacks may only declare interceptor binding types that are defined as @Target(TYPE). If an interceptor for lifecycle callbacks declares an interceptor binding type that is defined @Target({TYPE, METHOD}), the container automatically detects the problem and treats it as a definition error.

您已经使用 @PostConstruct init(InvocationContext ctx) 创建了一个生命周期回调。此回调旨在运行构建您正在拦截的 bean，因此将其应用于方法没有意义。

至于为什么旧的 @Interceptor 有效，documentation 中也有描述：

An around-invoke interceptor may be defined to apply only to a specific method of the target class. Likewise, an around-timeout interceptor may be defined to apply only to a specific timeout method of the target class. However, if an interceptor class that defines lifecycle callback interceptor methods is defined to apply to a target class at the method level, the lifecycle callback interceptor methods are not invoked.

至于这个：

I find EJB and Weld so awkward to use...

如果你放慢速度并边学边学，你会过得更轻松。您似乎在尝试随机的事情并且对结果感到困惑，如果您不熟悉 CDI 和 EJB，这是可以预料的。

我还担心您正在使用 @ManagedBean 注释。第一，它实际上是 deprecated，第二，它用于 JSF，您没有说您正在使用它。

Answer 2

多亏了@DavidS，我才得以成功。为他点赞。

他指给我看，@Interceptor里面的@PostConstruct和我想的不一样

下面是带注释的正确代码：

@Inherited
@InterceptorBinding
@Target({ TYPE, METHOD })
@Retention(RUNTIME)
@Documented
public @interface DetectIntegrityConstraintsViolation {
}


import javax.annotation.ManagedBean;
import javax.annotation.Resource;
import javax.ejb.SessionContext;
import javax.persistence.PersistenceContext;

@ManagedBean // make it a CDI bean. @Interceptor itself should be enough, but WildFly 8.1 seems to have a bug, since it doesn't work without this line.
@Interceptor
@DetectIntegrityConstraintsViolation
public class ReferentialIntegrityConstraintViolationInterceptor {

    @PersistenceContext
    private EntityManager em;

    @Resource(name = "java:comp/EJBContext") // injecting Java EE resource into CDI bean
    private SessionContext sessionContext;

    @AroundInvoke
    public Object processInvocation(InvocationContext ctx) throws Exception {
        // ...
    }
 }

现在我可以在我的 EJB bean 中使用了：

@DetectIntegrityConstraintsViolation
public User updateUser(final User user) {
    // ...
}

而不是：

@Interceptors(ReferentialIntegrityConstraintViolationInterceptor.class)
public User updateUser(final User user) {
    // ...
}

以后来的人说明：

@InterceptorBinding 机制来自于 CDI 世界，因此拦截器必须成为 CDI bean 本身。它会带来某些后果：

必须在 beans.xml
拦截器（如果bean-discovery-mode="annotated"）必须是一个CDI bean；所以用 @javax.interceptor.Interceptor 注释它。不幸的是 WildFly 8.1 似乎有一些错误，因为它拒绝在没有 @javax.annotation.ManagedBean.
一些Java EE 资源注入（如 EJB SessionContext）在拦截器中是通过 JNDI 完成的

@InterceptorBinding / CDI/ EJB 3.2 - 注入问题

@InterceptorBinding / CDI/ EJB 3.2 - problems with injection

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