httpsessionproxyvisitor.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 java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;

import com.jdon.container.ContainerWrapper;
import com.jdon.container.access.TargetMetaRequest;
import com.jdon.container.finder.ComponentKeys;
import com.jdon.container.visitor.data.SessionContext;
import com.jdon.util.Debug;

/**
 * using HttpSession as those components that need be cached
 * 
 * now there are three kinds type: ComponentKeys.PROXYINSTANCE_FACTORY
 * ComponentKeys.TARGETSERVICE_FACTORY; ComponentKeys.SESSIONCONTEXT_FACTORY;
 * 
 * PROXYINSTANCE_FACTORY and TARGETSERVICE_FACTORY are the factorys that create
 * components that need be optimized, if every time create these components, it
 * will cost performance.
 * 
 * ComponentKeys.SESSIONCONTEXT_FACTORY is the factory of the state data from the
 * web container.
 * 
 * Decorator patterns. Decoratee is ComponentOriginVisitor Decorator is this
 * class;
 * 
 * @see ComponentKeys container.xml
 * @author banq
 */
public class HttpSessionProxyVisitor implements ComponentVisitor, HttpSessionBindingListener {
    private final static String module = HttpSessionProxyVisitor.class.getName();

    /**
     * in this box there are the result objects of the components running that
     * need be optimized. note" not the components itself.
     * the key = components name + VisitableName(such as :ComponentKeys.PROXYINSTANCE_FACTORY);
     * the value is the result of components factory creating.
     * 
     * samples:
     * key: NewsManagerproxyInstanceFactoryVisitable
     * value: the dynamic proxy instance for NewsManager object
     * 
     * key:NewsManagertargetServiceFactoryVisitable
     * value: the NewsManager object
     *  
     */
    private Map componentsboxs = new HashMap();

    private ComponentVisitor componentVisitor;

    public HttpSessionProxyVisitor(ComponentVisitor componentVisitor) {
        this.componentVisitor = componentVisitor;
    }

    public ContainerWrapper getContainerWrapper() {
        return componentVisitor.getContainerWrapper();
    }

    public void valueBound(HttpSessionBindingEvent event) {
        Debug.logVerbose(" valueBound active, sessionId :" + event.getSession().getId(), module);
        componentsboxs.clear();

    }

    /**
     * session destroyed. remove all ejb references;
     */
    public void valueUnbound(HttpSessionBindingEvent event) {
        String sessionId = event.getSession().getId();
        Debug.logVerbose(" unvalueBound active, sessionId :" + sessionId, module);
        Debug.logVerbose(" unvalueUnbound active, componentsboxs size" + componentsboxs.size(), module);
        //removeObjects();
        componentsboxs.clear();
    }

    /**
     * the object type saved in componentsboxs is decided by the method"
     * visitableFactory.createVisitable. only ejb service need cached, pojo
     * service not need.
     * 
     * @param targetMetaDef
     *            TargetMetaDef
     * @return Object
     */
    public Object visit(TargetMetaRequest targetMetaRequest) {
        Object o = null;
        try {
            StringBuffer sb = new StringBuffer(targetMetaRequest.getTargetMetaDef().getCacheKey());
            sb.append(targetMetaRequest.getVisitableName());
            Debug.logVerbose(" get the optimized instance for the key " + sb.toString(), module);
            o = componentsboxs.get(sb.toString());
            if (o == null) {
                Debug.logVerbose(" first time visit: " + targetMetaRequest.getTargetMetaDef().getClassName(), module);
                o = componentVisitor.visit(targetMetaRequest);
                componentsboxs.put(sb.toString(), o);
            }
        } catch (Exception e) {
            Debug.logError("visit error: " + e);
        }
        return o;
    }
    
    public SessionContext visitSessionContext(TargetMetaRequest targetMetaRequest){
        Object sessionContext = componentsboxs.get(SessionContext.NAME);
        if (sessionContext == null) {
            Debug.logVerbose(" first time visit sessionContext: " + targetMetaRequest.getVisitableName(), module);
            sessionContext = componentVisitor.visit(targetMetaRequest);
            componentsboxs.put(SessionContext.NAME, sessionContext);
        }
        return (SessionContext)sessionContext;
    }

    /**
     * remove all ejb references
     */
    public void removeObjects() {
        /**
         * 
         * try { Iterator iter = componentsboxs.keySet().iterator(); while
         * (iter.hasNext()) { String key = (String) iter.next(); Object ccEjb =
         * (Object) componentsboxs.get(key); removeEJBObject(ccEjb); } } catch
         * (Exception ex) { Debug.logWarning(ex, module); } finally {
         * componentsboxs.clear(); }
         */

    }

    /**
     * destroy the EJB.
     * 
     * private void removeEJBObject(Object ccEjb) { if (ccEjb == null) return;
     * try { //这个EJB的remove方法需要被任何角色访问，因为此时principle为空 if (ccEjb instanceof
     * EJBLocalObject) { EJBLocalObject eo = ( (EJBLocalObject) ccEjb);
     * eo.remove(); } else if (ccEjb instanceof EJBObject) { EJBObject eo = (
     * (EJBObject) ccEjb); eo.remove(); } } catch (Exception re) {
     *  } }
     */
}