package org.g4studio.core.resource.support;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.g4studio.core.resource.Cache;
import org.g4studio.core.resource.Resource;
import org.g4studio.core.resource.ResourceException;
import org.g4studio.core.resource.ResourceHandler;
import org.g4studio.core.resource.ResourceLoader;
import org.g4studio.core.resource.ResourceManager;
/**
* AbstractResourceManager
*
* @author HuangYunHui|XiongChun
* @since 2010-2-5
*/
public abstract class AbstractResourceManager implements ResourceManager {
private final Log logger = LogFactory.getLog( this.getClass() );
private Cache cache;
private CacheManager cacheManager = null;
/**
* 是否检查资源修改
*/
private boolean checkModified = true;
private Map keyLocks = new HashMap();
private ResourceConfigMapping resourceConfigMapping;
private LoaderMapping loaderMapping;
private HandlerMapping handlerMapping;
private final static Object LOCK = new Object();
/**
* 执行资源管理的初始化操作
* 只会被调用一次
* @throws ResourceException
*/
public void init() throws ResourceException{
if ( cache != null ){
cache.init();
}
}
/**
* 执行清楚处理
* 只会被调用一次
* @throws ResourceException
*/
public void destroy() throws ResourceException{
if (cache != null ) {
cache.destroy();
}
}
/**
* @param pUri
* @return
*/
private Object getKeyLock(String pUri){
Object result = keyLocks.get(pUri);
if ( result == null ){
result = new Object();
keyLocks.put(pUri, result);
}
return result;
}
public Resource get(String pUri) throws ResourceException {
ResourceConfig resourceConfig = resourceConfigMapping.mapping(pUri);
boolean isCache = false;
if ( resourceConfig == null ){
final String msg =
"没有找到资源: " + pUri + " 对应的配置项目，请检查配置文件中是否存在与之匹配的uri模式!";
logger.debug(msg);
return null;
}
ResourceLoader loader = null;
isCache = resourceConfig.isCache();
loader = loaderMapping.mapping(resourceConfig.getLoaderName());
Resource result = cacheManager.get(pUri);
if ( result != null ){
if ( checkModified == false ){//不检查修改
return result;
}
//检查资源是否已修改
long lastModified = result.getLastModified();
long newModified = loader.getLastModified(pUri);
if ( newModified > lastModified){
Object keyLock = null;
synchronized( LOCK ){
keyLock = getKeyLock(pUri);
}
synchronized(keyLock){
result = loadResource(loader, pUri);
cacheManager.put(result);
}
}
return result;
}
Object keyLock = null;
synchronized( LOCK ){
keyLock = getKeyLock(pUri);
}
synchronized(keyLock){
result = cacheManager.get(pUri);
if ( result != null ){
return result;
}
result = loadResource(loader, pUri);
//如果cache 才需要把资源缓存起来
if ( isCache ){
cacheManager.put(result);
}
return result;
}
}
/**
* 负责装载资源，调用hanlder进行资源处理，
* 注意：对资源进行处理的过程中，如果有一个处理过程出错了，放弃整个处理，
* 返回最原始的导入的数据.
* @param pLoader
* @param pUri
* @return
*/
private Resource loadResource(ResourceLoader pLoader , String pUri){
Resource res = null;
ResourceConfig resourceConfig = resourceConfigMapping.mapping(pUri);
if ( resourceConfig == null ){
res = pLoader.load(pUri);
return res;
} else {
res = pLoader.load(
newURI( pUri,
resourceConfig.getOldPrefix(),
resourceConfig.getNewPrefix()) );
}
String[] handlers = resourceConfig.getHandlerNames();
for(int i=0; i<handlers.length; i++){
String handerName = handlers[i];
ResourceHandler handler = handlerMapping.mapping(handerName);
if ( handler == null ){
logger.warn("没有找到名为:" + handerName + "的资源处理器");
continue;
}
try{
handler.handle(res);
}catch(Exception ex){
logger.warn("对资源:" + pUri + "进行:" + handerName + " 处理时出现异常!", ex );
continue;
}
}
return res;
}
private static String newURI(String pUri, String pOldPrefix, String pNewPrefix ){
if ( pUri == null ){
return null;
}
if ( pOldPrefix == null || pNewPrefix == null ){
return pUri;
}
if ( pUri.startsWith(pOldPrefix) ){
return pNewPrefix + pUri.substring(pOldPrefix.length());
} else {
return pUri;
}
}
public Cache getCache() {
return cache;
}
public void setCache(Cache cache) {
this.cache = cache;
this.cacheManager = new CacheManager(cache);
}
public HandlerMapping getHandlerMapping() {
return handlerMapping;
}
public void setHandlerMapping(HandlerMapping handlerMapping) {
this.handlerMapping = handlerMapping;
}
public LoaderMapping getLoaderMapping() {
return loaderMapping;
}
public void setLoaderMapping(LoaderMapping loaderMapping) {
this.loaderMapping = loaderMapping;
}
public ResourceConfigMapping getResourceConfigMapping() {
return resourceConfigMapping;
}
public void setResourceConfigMapping(ResourceConfigMapping resourceConfigMapping) {
this.resourceConfigMapping = resourceConfigMapping;
}
public boolean isCheckModified() {
return checkModified;
}
public void setCheckModified(boolean checkModified) {
this.checkModified = checkModified;
}
}