jbpmejbservicelocator.java

一个java工作流引擎

package org.jbpm.ejb;

import java.rmi.*;
import java.util.*;
import javax.ejb.*;
import javax.naming.*;
import javax.rmi.*;

/**
 * fetches the jbpm ejb service objects from a local or remote JNDI repository.
 * See also <a href="http://java.sun.com/j2se/1.3/docs/api/javax/naming/Context.html">
 * http://java.sun.com/j2se/1.3/docs/api/javax/naming/Context.html</a>
 */
public class JbpmEjbServiceLocator {
  
  private Hashtable environment = null;

  public JbpmEjbServiceLocator() {
  }

  public JbpmEjbServiceLocator( Hashtable environment ) {
    this.environment = environment;
  }

  /**
   * retrieves an ExecutionServiceRemote object from a JNDI registry.
   * throws EjbDeploymentException when this service locator was not able to return a ExecutionServiceRemote.
   */
  public ExecutionServiceRemote getExecutionServiceRemote() throws EjbDeploymentException {
    ExecutionServiceRemote executionService = null;
    
    InitialContext initialContext = getInitialContext();
    String jndiName = "java/JbpmExecutionService";
    try {
			Object executionServiceHomeObject = initialContext.lookup( jndiName );
			ExecutionServiceRemoteHome executionServiceHome = (ExecutionServiceRemoteHome) PortableRemoteObject.narrow( executionServiceHomeObject, ExecutionServiceRemoteHome.class );
			executionService = executionServiceHome.create();
		} catch (ClassCastException e) {
			e.printStackTrace();
      throw new EjbDeploymentException( "couldn't create a ExecutionServiceRemote object : object under jndi-name '" + jndiName + "' was not castable to a ExecutionServiceRemoteHome", e );
		} catch (RemoteException e) {
			e.printStackTrace();
      throw new EjbDeploymentException( "couldn't create a ExecutionServiceRemote object from jndi-name '" + jndiName + "'", e );
    } catch (NamingException e) {
			e.printStackTrace();
      throw new EjbDeploymentException( "couldn't create a ExecutionServiceRemote object : no object was registered with jndi-name '" + jndiName + "'", e );
    } catch (CreateException e) {
			e.printStackTrace();
      throw new EjbDeploymentException( "couldn't create a ExecutionServiceRemote", e );
    }
    
    return executionService;
  }

  /**
   * @throws EjbRuntimeException if the executionServiceRemote could not be removed from the container.
   */
	public void release( ExecutionServiceRemote executionServiceRemote ) {
    try {
			executionServiceRemote.remove();
		} catch (RemoteException e) {
			e.printStackTrace();
      throw new EjbRuntimeException( "couldn't remove executionServiceRemote because of a RemoteException", e );
		} catch (RemoveException e) {
			e.printStackTrace();
      throw new EjbRuntimeException( "couldn't remove executionServiceRemote because of a RemoveException", e );
    }
  }

  private InitialContext getInitialContext() throws EjbDeploymentException {
    InitialContext initialContext = null;
    
    try {
      if ( environment!=null ) {
        initialContext = new InitialContext( environment );
      } else {
        initialContext = new InitialContext();
      }
    } catch (NamingException e) {
      e.printStackTrace();
      throw new EjbDeploymentException( "couldn't get the initial context", e );
    }

    return initialContext;
  }
}