visitorfactory.java

Java/J2EE框架Jdon-Framework系统的Sample

/**
 * Copyright 2005 Jdon.com
 * 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 com.jdon.bussinessproxy.cache;

import javax.servlet.http.HttpServletRequest;
import com.jdon.bussinessproxy.TargetMetaDef;
import javax.servlet.http.HttpSession;
import com.jdon.util.Debug;


public class VisitorFactory {

  private final static String module =  VisitorFactory.class.getName();

  private VisitableFactory visitableFactory;
  public VisitorFactory(VisitableFactory visitableFactory){
    this.visitableFactory  = visitableFactory;
  }

  public  ComponentCacheVisitor createCacheVisitor(
      HttpServletRequest request, TargetMetaDef targetMetaDef) {

    HttpSession session = request.getSession();
    String cmKey = targetMetaDef.getCacheKey() ;
    if (cmKey == null){
      Debug.logError("cacheKey is null " + targetMetaDef.getClassName(), module);
    }
    cmKey = cmKey + module;
    ComponentCacheVisitor cm = (ComponentCacheVisitor)
        session.getAttribute(cmKey);
    if (cm == null) {
      cm = new HttpSessionProxyVisitor(visitableFactory);
      //下行执行后，将激活HttpSessionVisitor中的valueBound
      session.setAttribute(cmKey, cm);
    }
    return cm;

  }

}