CDI + EJB 3+ EJB事务

Question

我需要审计ejb bean的调用。说审计，我指的是写信息，如当前日志记录的用户，方法名称，数据库的附加描述。我决定用CDI装饰器来做：

@Decorator
public class AccountServiceBeanDecorator implements AccountService {

  @Inject
  @Delegate
  @Any
  AccountService accountService;

  @EJB
  private AuditService auditService;

  @Override
  public Account createAccount(Account account) {
    auditService.saveAudit("Method: createAccount", currentUser, "Creating account by admin");
    return accountService.createAccount(account);
  }

}

还有被装饰的班级：

@Stateless
public class AccountServiceBean implements AccountService {

   @Override
   public Account createAccount(Account account) {
     ... 
   }
}

现在，如果我从另一个ejb无状态bean调用AccountService，那么事务会发生什么情况呢？

@Stateless
public ApplicationFacadeBean implements ApplicationFacade {

  @EJB
  private AccountService accountService;

  @Override
  public Account createAccount(Account account) {
    return accountService.createAccount(account);
  }

}

我想记录装饰器(AccountServiceBeanDecorator)和装饰类(AccountServiceBean)中的事务状态，所以我在这两个类中注入了TransactionSynchronizationRegistry作为资源：

@Decorator
public class AccountServiceBeanDecorator implements AccountService {

  @Inject
  @Delegate
  @Any
  AccountService accountService;

  @EJB
  private AuditService auditService;

  @Resource
  private TransactionSynchronizationRegistry reg;

  @Override
  public Account createAccount(Account account) {
    log.info("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%");
    log.info("tx ({}): {}", new Object[] {reg.getTransactionStatus(), reg.getTransactionKey()});
    log.info("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%");
    auditService.saveAudit("Method: createAccount", currentUser, "Creating account by admin");
    return accountService.createAccount(account);
  }

}

和

@Stateless
public class AccountServiceBean implements AccountService {

   @Resource
   private TransactionSynchronizationRegistry reg;

   @Override
   public Account createAccount(Account account) {

    log.info("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%");
    log.info("tx ({}): {}", new Object[] {reg.getTransactionStatus(), reg.getTransactionKey()});
    log.info("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%");
     ... 
   }
}

我收到了奇怪的行为：

• 来自装潢师的日志 tx (0)：JavaEETransactionImpl: txId=6 nonXAResource=null jtsTx=null localTxStatus=0 localTxStatus=0
• 第二个日志上的NullPointerException (reg为空)。

有人能给我解释一下吗？Wheter类在与ApplicationFacade相同的事务中被调用？

谢谢

Answer 1

first: i不会将ejbs与cdi拦截器混合。ejbs将其用于拦截器实现。

第二步：拦截器在与拦截器所在的事务相同的事务中执行。

可能的解决方案：

• 创建正确的ejb拦截器
• 将拦截器放在方法/类周围
• 使用以下方法创建第二个ejb (MyLoggerBean) (字符串消息)，并使用@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)对该方法进行注释
• 在拦截器内部创建如下类成员：@EJB私有MyLoggerBean loggerBean
• 在@AroundInvoke注释的方法中，可以调用loggerBean。logToDatabase(.)

这将从拦截器所在的ejb当前事务中创建一个新事务。

--我知道我的英语不是很好。但我希望你明白我认为什么应该有效。如果我有时间，我在github上做个例子.

Answer 2

嗯..。你用的是什么容器？通常，我不会怀疑CDI装饰师在EJB上工作.我想不出在JEE规范中我遇到的任何东西都能提供证据。

但是，面对你的问题，我是用拦截器，而不是装饰器。这些都得到EJB规范的支持.总之，这是我的代码，在您的情况下，您需要从上下文中获取变量：

import java.lang.reflect.Method;

import javax.inject.Inject;
import javax.interceptor.AroundInvoke;
import javax.interceptor.Interceptor;
import javax.interceptor.InvocationContext;

public class InvocationCountInterceptor {
    @Inject
    private InvocationCounter counter;

    @AroundInvoke
    public Object intercept(InvocationContext ctx) throws Exception {
        Object returnValue = ctx.proceed();
        Class<? extends Object> className = ctx.getTarget().getClass();
        Method methodName = ctx.getMethod();
        counter.incrementCounter(className, methodName);
        return returnValue;
    }
}

然后，不管您想要审计哪个EJB或EJB方法，我只是添加了以下内容：@Interceptors(InvocationCountInterceptor.class)