countcacheadvice.java

基于java的组号查询模块

/**
 * 
 */
package com.lily.dap.dao;

import java.io.Serializable;
//import java.lang.reflect.Method;

import net.sf.ehcache.Cache;
import net.sf.ehcache.Element;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.Assert;

import com.lily.dap.model.QueryCondition;

/**
 * 对AbstractDaoHibernate的count和executeSQLCount进行缓存
 * 缓存时间在WEB-INF\classes\ehcache.properties中定义，默认为5分钟
 * 对于大数据量的数据查询，发现在查出的结果数据进行翻页时，都必须做记录合计查询，如果数据很大时速度会很慢，所以对这个合计值进行缓存
 * 
 * @author zouxuemo
 *
 */
public class CountCacheAdvice implements MethodInterceptor {
    protected final Log logger = LogFactory.getLog(getClass());
    
    protected Cache cache;
    
	/**
	 * @param cache the cache to set
	 */
	public void setCache(Cache cache) {
		this.cache = cache;
	}
	
	/**
	 * 检查是否提供必要参数。
	 */
	public void afterPropertiesSet() throws Exception {
	    Assert.notNull(cache, "A cache is required. Use setCache(Cache) to provide one.");
	}

	public Object invoke(MethodInvocation invocation) throws Throwable {
	    String methodName  = invocation.getMethod().getName();
	    Object[] arguments = invocation.getArguments();
	    Object result;

	    String cacheKey = getCacheKey(methodName, arguments);
	    Element element = cache.get(cacheKey);
	    
	    if (element != null)
	    	logger.debug("look cache for (" + cacheKey + "), find value [" + element.getValue() + "].");
	    else
	    	logger.debug("look cache for (" + cacheKey + "), not find value.");
	    
	    if (element == null) {
	    	result = invocation.proceed();
	    	
	    	logger.debug("put value [" + result + "] to cache (" + cacheKey + ").");
	    	
	    	element = new Element(cacheKey, (Serializable)result);
	    	cache.put(element);
	    }
	    return element.getValue();
	}
	
	private String getCacheKey(String methodName, Object[] arguments) {
		StringBuffer sb = new StringBuffer();
		sb.append(methodName);
		
		if ("count".equals(methodName)) {
			Class clazz = (Class)arguments[0];
			QueryCondition queryCondition = (QueryCondition)arguments[1];
			
			sb.append(".").append(clazz.getName());
			sb.append("[").append(queryCondition.getConditions()).append("]");
		} else if ("executeSQLCount".equals(methodName)) {
			String sql = (String)arguments[0];
			sb.append(".[").append(sql).append("]");
		} else if ((arguments != null) && (arguments.length != 0)) {
			for (int i=0; i<arguments.length; i++) {
				sb.append(".").append(arguments[i]);
			}
		}
		
		return sb.toString();

	}
}