visitorfactory.java

一个非常好的FRAMWRK!是一个外国组织做的!不!

/**
 * Copyright 2003-2005 the original author or authors.
 * 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.container.visitor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import com.jdon.bussinessproxy.TargetMetaDef;
import com.jdon.util.Debug;

/**
 * Factory that get visitors for the container that have been optimized by
 * cache(HttpSession)
 * 
 * replace this class in container.xml ,we can change HttpSession 
 * with another session type, HttpSession is binding to Web container.
 * 
 * 
 * <p>
 * 
 * @author <a href="mailto:[e-mail]">banq </a>
 *         </p>
 */
public class VisitorFactory {

    private final static String module = VisitorFactory.class.getName();
    
    private ComponentVisitor componentVisitor;
    
    /**
     * @param componentVisitor
     */
    public VisitorFactory(ComponentVisitor componentVisitor) {
        this.componentVisitor = componentVisitor;
    }
    /**
     * return a ComponentVisitor with cache.
     * the httpSession is used for optimizing the component performance
     * @param request
     * @param targetMetaDef
     * @return
     */
    public  ComponentVisitor getVisitor(HttpServletRequest request,
            TargetMetaDef targetMetaDef) {
        HttpSession session = request.getSession();
        ComponentVisitor cm = (ComponentVisitor)session.getAttribute("HttpSessionProxyVisitor");
        if (cm == null){
            Debug.logVerbose(" first time get ComponentVisitor ", module);
            cm = new HttpSessionProxyVisitor(componentVisitor);
            session.setAttribute("HttpSessionProxyVisitor", cm);
        }
        return cm;
    }

    /**
     * return a ComponentVisitor without cache.
     * @param request
     * @param targetMetaDef
     * @param cw
     * @return
     */
    public  ComponentVisitor getVisitor(TargetMetaDef targetMetaDef) {   
        return componentVisitor;

    }

}