/**
* Copyright (c) 2011-2013, James Zhan 詹波 (jfinal@126.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.jfinal.plugin.ehcache;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import javax.servlet.http.HttpServletRequest;
import com.jfinal.aop.Interceptor;
import com.jfinal.core.ActionInvocation;
import com.jfinal.core.Controller;
import com.jfinal.render.Render;
/**
* CacheInterceptor.
*/
public class CacheInterceptor implements Interceptor {
private static final String renderKey = "$renderKey$";
private static volatile ConcurrentHashMap<String, ReentrantLock> lockMap = new ConcurrentHashMap<String, ReentrantLock>();
private ReentrantLock getLock(String key) {
ReentrantLock lock = lockMap.get(key);
if (lock != null)
return lock;
lock = new ReentrantLock();
ReentrantLock previousLock = lockMap.putIfAbsent(key, lock);
return previousLock == null ? lock : previousLock;
}
final public void intercept(ActionInvocation ai) {
Controller controller = ai.getController();
String cacheName = buildCacheName(ai, controller);
String cacheKey = buildCacheKey(ai, controller);
Map<String, Object> cacheData = CacheKit.get(cacheName, cacheKey);
if (cacheData == null) {
Lock lock = getLock(cacheName);
lock.lock(); // prevent cache snowslide
try {
cacheData = CacheKit.get(cacheName, cacheKey);
if (cacheData == null) {
ai.invoke();
cacheAction(cacheName, cacheKey, controller);
return ;
}
}
finally {
lock.unlock();
}
}
useCacheDataAndRender(cacheData, controller);
}
// TODO 考虑与 EvictInterceptor 一样强制使用 @CacheName
private String buildCacheName(ActionInvocation ai, Controller controller) {
CacheName cacheName = ai.getMethod().getAnnotation(CacheName.class);
if (cacheName != null)
return cacheName.value();
cacheName = controller.getClass().getAnnotation(CacheName.class);
return (cacheName != null) ? cacheName.value() : ai.getActionKey();
}
private String buildCacheKey(ActionInvocation ai, Controller controller) {
StringBuilder sb = new StringBuilder(ai.getActionKey());
String urlPara = controller.getPara();
if (urlPara != null)
sb.append("/").append(urlPara);
String queryString = controller.getRequest().getQueryString();
if (queryString != null)
sb.append("?").append(queryString);
return sb.toString();
}
private void cacheAction(String cacheName, String cacheKey, Controller controller) {
HttpServletRequest request = controller.getRequest();
Map<String, Object> cacheData = new HashMap<String, Object>();
for (Enumeration<String> names=request.getAttributeNames(); names.hasMoreElements();) {
String name = names.nextElement();
cacheData.put(name, request.getAttribute(name));
}
cacheData.put(renderKey, controller.getRender()); // cache render
CacheKit.put(cacheName, cacheKey, cacheData);
}
private void useCacheDataAndRender(Map<String, Object> cacheData, Controller controller) {
HttpServletRequest request = controller.getRequest();
Set<Entry<String, Object>> set = cacheData.entrySet();
for (Iterator<Entry<String, Object>> it=set.iterator(); it.hasNext();) {
Entry<String, Object> entry = it.next();
request.setAttribute(entry.getKey(), entry.getValue());
}
request.removeAttribute(renderKey);
controller.render((Render)cacheData.get(renderKey)); // set render from cacheData
}
}