bsfeventprocessor.java

Bean Scripting Framework (BSF)为在java应用中使用脚本语言

/*
 * Copyright 2004,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.bsf.util;

import org.apache.bsf.BSFEngine;
import org.apache.bsf.BSFException;
import org.apache.bsf.BSFManager;
import org.apache.bsf.util.event.EventProcessor;

/**
 * This is used to support binding scripts to be run when an event
 * occurs.
 *
 * @author Sanjiva Weerawarana
 */
public class BSFEventProcessor implements EventProcessor {
  BSFEngine engine;
  BSFManager manager;
  String filter;
  String source;
  int lineNo;
  int columnNo;
  Object script;

  /**
   * Package-protected constructor makes this class unavailable for
   * public use.
   */
  BSFEventProcessor (BSFEngine engine, BSFManager manager, String filter,
		     String source, int lineNo, int columnNo, Object script)
	   throws BSFException {
	this.engine = engine;
	this.manager = manager;
	this.filter = filter;
	this.source = source;
	this.lineNo = lineNo;
	this.columnNo = columnNo;
	this.script = script;
  }
  //////////////////////////////////////////////////////////////////////////
  //
  // event is delegated to me by the adapters using this. inFilter is
  // in general the name of the method via which the event was received
  // at the adapter. For prop/veto change events, inFilter is the name
  // of the property. In any case, in the event processor, I only forward
  // those events if for which the filters match (if one is specified).

  public void processEvent (String inFilter, Object[] evtInfo) {
	try {
	  processExceptionableEvent (inFilter, evtInfo);
	} catch (RuntimeException re) {
	  // rethrow this .. I don't want to intercept run-time stuff
	  // that can in fact occur legit
	  throw re;
	} catch (Exception e) {
	  // should not occur
	  System.err.println ("BSFError: non-exceptionable event delivery " +
			  "threw exception (that's not nice): " + e);
	  e.printStackTrace ();
	}
  }
  //////////////////////////////////////////////////////////////////////////
  //
  // same as above, but used when the method event method may generate
  // an exception which must go all the way back to the source (as in
  // the vetoableChange case)

  public void processExceptionableEvent (String inFilter, Object[] evtInfo) throws Exception
  {
	if ((filter != null) && !filter.equals (inFilter)) {
	  // ignore this event
	  return;
	}

	// run the script
	engine.exec (source, lineNo, columnNo, script);
  }
}