在CDI上运行时自动执行Injectind

Question

我试图找出CDI和适合我需要的最佳方法。我有一个与普通tcp通信交互的服务（TcpServiceImpl）。现在这个服务有一些地方需要通知某人发生了什么事情。对于这些信息，我有接口TcpConnection，需要将其CDI注入到正确的实现中。另一个问题是服务TcpServiceImpl本身被注入一个作业（TcpConnectionJob）中，该作业定期执行并调用服务来完成任务。这意味着服务TcpServiceImpl将多次存在。每个都有它处理的另一个tcp连接，并且有另一个需要在接口中注入另一个驱动程序/协议的设备TcpConnection。

让我展示参与此场景的三个要素：

以下是将获得多个实现的接口：

public interface TcpConnection
{

  /**
   * Connected.
   *
   * @throws NGException the NG exception
   */
  public void connected() throws NGException;

  /**
   * This method will send the received data from the InputStream of the connection.
   *
   * @param data the received data
   * @throws NGException the  NG exception
   */
  public void received( byte[] data ) throws NGException;

  /**
   * Usable for the protocol to send data to the device.
   *
   * @param data the data to send to the device ( Will be converted to byte[] with getBytes() )
   * @throws NGException the  NG exception
   */
  public void send( String data ) throws NGException;

  /**
   * Usable for the protocol to send data to the device.
   *
   * @param data the data to send to the device ( Will be send as is )
   * @throws NGException the NG exception
   */
  public void send( byte[] data ) throws NGException;

  /**
   * This method will inform the protocol that the connection got closed.
   *
   * @throws NGException the NG exception
   */
  public void closed() throws NGException;
}

另外，下面是在我的现有服务中何时调用此函数的示例片段：

public class TCPServiceImpl implements TCPService, Runnable
{
/** The callback. */
private TcpConnection callback;
private void disconnect()
{
  connection.disconnect();
  if ( !getStatus( jndiName ).equals( ConnectionStatus.FAILURE ) )
  {
     setStatus( ConnectionStatus.CLOSED );
  }
  /* TODO: Tell driver connection is closed! */
  callback.closed();
}
}

下面是调用服务的类，然后需要为接口动态注入正确的实现。

public class TcpConnectionJob implements JobRunnable
{
  /** The service. */
  private TCPService service;

  public void execute()
  {
    service.checkConnection( connection );
  }
}

服务注入回调必须链接到将转换数据或处理设备逻辑的正确“协议”或“驱动程序”的实现。接口将有多个不同的驱动程序实现，我需要注入正确的驱动程序实现。此决定的限定符可以是设备的名称。现在我看了以下链接：

理解CDI中类型安全的必要性

如何以编程方式查找和注入CDI托管bean，其中限定符包含类的名称

如何在多个类实现中使用CDI限定符？

问题:

但我仍然不确定使用哪种方式/方法以及正确的方式是什么。任何帮助都将不胜感激。

我的第一个想法是将我的接口复制到一个限定符接口，并在这个接口的后面添加输入限定符的可能性。这是个好主意吗？

Answer 1

这就是我想出的解决方案。现在唯一的问题是得到一个工作回调，但那是不同的。以下是对我有效的解决方案：

/**
 * The Qualifier interface TcpDriver. The value of this annotation is the name the implementation
 * is found under. Please only enter values that are configured in the wildfly config as the name of
 * the device.
 */
@Documented
@Qualifier
@Retention( RUNTIME )
@Target( { TYPE, FIELD, METHOD, PARAMETER } )
public @interface TcpDriver
{

  /**
   * Value.
   *
   * @return the string
   */
  String value();
}

仅针对限定符接口的默认实现：

/**
 * The Class TcpDriverImpl.
 */
public class TcpDriverImpl extends AnnotationLiteral<TcpDriver> implements TcpDriver
{

  /** The Constant serialVersionUID. */
  private static final long serialVersionUID = 1L;

  /** The name. */
  private final String name;

  /**
   * Instantiates a new tcp driver impl.
   *
   * @param name the name
   */
  public TcpDriverImpl( final String name )
  {
    this.name = name;
  }

  /** {@inheritDoc} */
  @Override
  public String value()
  {
    return name;
  }

}

现在有一个测试实现来测试它：

@TcpDriver( "terminal1" )
@Dependent
public class TestDriverImpl implements TcpConnection
{

  /** The log. */
  private Log log;

  @Inject
  public void init( Log log )
  {
    this.log = log;
  }

  @Override
  public void connected() throws NGException
  {
    // TODO Auto-generated method stub
    log.info( "IT WORKS!!" );
  }

  @Override
  public void received( byte[] data ) throws NGException
  {
    // TODO Auto-generated method stub

  }

  @Override
  public void send( String data ) throws NGException
  {
    // TODO Auto-generated method stub

  }

  @Override
  public void send( byte[] data ) throws NGException
  {
    // TODO Auto-generated method stub

  }

  @Override
  public void closed() throws NGException
  {
    // TODO Auto-generated method stub
    log.info( "BYE BYE" );
  }

}

最后但并非最不重要的一点是，我将所有这些注入到我的服务中的方式：

  /** The callback Instance for the driver to find. */
  @Inject
  @Any
  private Instance<TcpConnection> callback;

  private TcpConnection driver;
  /**
  * Inject driver.
  */
  private void injectDriver()
  {
    final TcpDriver driver = new TcpDriverImpl( name );
    this.driver = callback.select( driver ).get();
  }

我希望这能帮助那些和我有同样要求的人。

PS：如果您在测试实现中检查日志输出，然后查看日志，那么可以使用一个小日志来显示它的工作原理：）

2017-02-28 08:37:00,011 INFO  starting TCPConnection: TcpDevice1 with status: NOT_CONNECTED
2017-02-28 08:37:00,018 INFO  initializing terminal1
2017-02-28 08:37:00,019 INFO  Creating socket for: terminal1 with port: XXXXX
2017-02-28 08:37:00,023 INFO  Updated Status to CONNECTED for connection TcpDevice1
2017-02-28 08:37:00,024 INFO  opened connection to terminal1
2017-02-28 08:37:00,026 INFO  (terminal1) IT WORKS!!
2017-02-28 08:37:00,038 INFO  (terminal1) terminal1: In threaded method run
2017-02-28 08:37:00,039 INFO  (terminal1) waiting for data...
2017-02-28 08:39:00,045 INFO  (terminal1) Socket closed!
2017-02-28 08:39:00,045 INFO  (terminal1) BYE BYE

Answer 2

使用CDI事件，不要使用回调阻塞。一些资源：

https://docs.oracle.com/javaee/7/tutorial/cdi-adv005.htm

http://www.adam-bien.com/roller/abien/entry/java_ee_6_observer_with

http://www.next-presso.com/2014/06/you-think-you-know-everything-about-cdi-events-think-again/