加速Web处理之Web缓存

下面是Web动态缓存技术的一种实现，是对网上代码的改进。在Web开发过程中可以将不经常更新的数据放在缓存中，从而减少数据库的操作次数，有效加快Web处理速度:

1.缓存数据类:

package com.suyun.cache; import java.io.Serializable; public class CacheData implements Serializable { private Object data; private long time; private int count; public CacheData() { super(); } public CacheData(Object data, long time, int count) { super(); this.data = data; this.time = time; this.count = count; } public CacheData(Object data) { super(); this.data = data; this.time = System.currentTimeMillis(); this.count = 1; } public int getCount() { return count; } public void setCount(int count) { this.count = count; } public Object getData() { return data; } public void setData(Object data) { this.data = data; } public long getTime() { return time; } public void setTime(long time) { this.time = time; } public void addCount(){ this.count++; } }

2.缓存操作类:

package com.suyun.cache; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.Arrays; import java.util.Hashtable; import java.util.List; import org.apache.log4j.Logger; public class CacheOpration { private static final Logger logger = Logger.getLogger(CacheOpration.class); private static CacheOpration singleton = null; private Hashtable cacheMap; //存放缓存数据 private List threadKeys; //处于线程更新中的key值列表 private CacheOpration(){ this.cacheMap = new Hashtable(); this.threadKeys = new ArrayList(); } public static CacheOpration getInstance(){ if(singleton==null){ singleton = new CacheOpration(); } return singleton; } private void addCacheData(String key,Object data,boolean check){ long freeMemory = Runtime.getRuntime().freeMemory(); logger.info("剩余内存:"+freeMemory); if(freeMemory<1024*1024){ logger.warn("WEB缓存：内存不足，开始清空缓存！"); removeAllCacheData(); return; } else if(check && cacheMap.containsKey(key)){ logger.warn("WEB缓存：key值= " + key + " 在缓存中重复, 本次不缓存！"); return; } cacheMap.put(key, new CacheData(data)); } /** * 添加数据缓存(与方法getCacheData(String key, long intervalTime, int maxVisitCount)配合使用) * @param key * @param data */ public void addCacheData(String key,Object data){ addCacheData(key, data, true); } /** * 取得缓存中的数据 * @param key * @param intervalTime 缓存的时间周期，小于等于0时不限制 * @param maxVisitCount 访问累积次数，小于等于0时不限制 * @return */ public Object getCacheData(String key,long intervalTime,int maxVisitCount){ CacheData cacheData = (CacheData) cacheMap.get(key); if(cacheData==null){ return cacheData; } if(intervalTime>0 && (System.currentTimeMillis()-cacheData.getTime())>intervalTime){ removeCacheData(key); return null; } if(maxVisitCount>0 && (maxVisitCount-cacheData.getCount())<=0){ removeCacheData(key); return null; } else{ cacheData.addCount(); } return cacheData.getData(); } /** * 当缓存中数据失效时，用不给定的方法线程更新数据 * @param obj 取得数据的对像(该方法是静态方法是不用实例，则传Class实列) * @param methodName 该对像中的方法 * @param params 该方法的参数列表(参数列表中对像都要实现toString方法,若列表中某一参数为空则传它所属类的Class) * @param intervalTime 缓存的时间周期，小于等于0时不限制 * @param maxVisitCount 访问累积次数，小于等于0时不限制 * @return */ public Object getCacheData(Object obj,String methodName,Object[]params,long intervalTime,int maxVisitCount){ Class oc = obj instanceof Class?(Class)obj:obj.getClass(); StringBuffer key = new StringBuffer(oc.getName()); key.append("-").append(methodName); if(params!=null){ for(int i=0;i<params.length;i++){ Object param = params[i]; if(param instanceof Object[]){ key.append("-").append(Arrays.toString((Object[])param)); } else{ key.append("-").append(param); } } } CacheData cacheData = (CacheData) cacheMap.get(key.toString()); if(cacheData==null){ Object returnValue = invoke(obj, methodName, params, key.toString()); return returnValue instanceof Class?null:returnValue; } if(intervalTime>0 && (System.currentTimeMillis()-cacheData.getTime())>intervalTime){ daemonInvoke(obj, methodName, params, key.toString()); ///缓存时间超时,启动线程更新数据 } else if(maxVisitCount>0 && (maxVisitCount-cacheData.getCount())<=0){ daemonInvoke(obj, methodName, params, key.toString()); //访问次数超出,启动线程更新数据 } else{ cacheData.addCount(); } return cacheData.getData(); } /** * 递归调用给定方法更新缓存中数据 * @param obj * @param methodName * @param params * @param key * @return 若反射调用方法返回值为空则返回该值的类型 */ private Object invoke(Object obj,String methodName,Object[]params,String key){ Object returnValue = null; Class[]pcs = null; try { if(params!=null && params.length>0){ pcs = new Class[params.length]; for(int i=0;i<params.length;i++){ Object param = params[i]; if(param instanceof MethodInfo){ //参数类型是MethodInfo则调用该方法的返回值做这参数 MethodInfo pmi = (MethodInfo) param; Object pre = invoke(pmi.getObj(),pmi.getMethodName(),pmi.getParams(),null); params[i] = pre; } else if(param instanceof Class){ pcs[i] = (Class)param; params[i] = null; } else{ pcs[i] = param.getClass(); } } } Class oc = obj instanceof Class?(Class)obj:obj.getClass(); //logger.info(oc.getName()); Method method = matchMethod(oc, methodName, pcs); //logger.info(method.getName()); returnValue = method.invoke(obj, params); if(key!=null && returnValue!=null){ addCacheData(key, returnValue,false); } else if(returnValue==null){ returnValue = method.getReturnType(); } } catch (Exception e) { logger.error("调用方法失败,methodName=" + methodName, e); if(key!=null){ removeCacheData(key); logger.error("更新缓存失败，缓存key=" + key, e); } } return returnValue; } /** * 找不到完全匹配的方法时,对参数进行向父类匹配 * @param oc 类型 * @param methodName 方法名 * @param pcs 参数 * @return */ private Method matchMethod(Class oc,String methodName,Class[]pcs){ Method method = null; try { method = oc.getMethod(methodName, pcs); } catch (NoSuchMethodException e) { Method[]methods = oc.getDeclaredMethods(); for(int i=0;i<methods.length;i++){ if(methods[i].getName().equals(methodName)){ Class[]pts = methods[i].getParameterTypes(); if(pts.length==pcs.length){ for(int j=0;j<pts.length;j++){ if(pts[j].isAssignableFrom(pcs[j])){ method = methods[i]; break; } } } } } } return method; } /** * 新启线程后台调用给定方法更新缓存中数据 * @param obj * @param methodName * @param params * @param key */ private void daemonInvoke(Object obj,String methodName,Object[]params,String key){ if(!threadKeys.contains(key)){ InvokeThread thread = new InvokeThread(obj,methodName,params,key); thread.start(); } } /** * 移除缓存中的数据 * @param key */ public void removeCacheData(String key){ logger.info("移除缓存:"+key); cacheMap.remove(key); } /** * 移除所有缓存数据 * */ public void removeAllCacheData(){ logger.info("移除所有缓存数据!"); cacheMap.clear(); } @Override public String toString() { StringBuffer buffer = new StringBuffer("***********"); buffer.append("正在更新的缓存数据："); for(int i=0;i<threadKeys.size(); i++){ buffer.append(threadKeys.get(i)).append(","); } buffer.append("当前缓存大小：").append(cacheMap.size()).append(","); buffer.append("***********"); return buffer.toString(); } private class InvokeThread extends Thread { private Object obj; private String methodName; private Object[]params; private String key; public InvokeThread() { super(); } public InvokeThread(Runnable target, String name) { super(target, name); } public InvokeThread(Runnable target) { super(target); } public InvokeThread(String name) { super(name); } public InvokeThread(Object obj, String methodName, Object[] params, String key) { super(); this.obj = obj; this.methodName = methodName; this.params = params; this.key = key; } @Override public void run() { logger.info("后台进程正在运行!"); threadKeys.add(key); invoke(obj, methodName, params, key); threadKeys.remove(key); } } }

3.实验数据类：

package com.suyun.cache; import java.util.Arrays; import java.util.List; public class DataCreator { private List<Object> dataList; private String[]array; private int maxNum; public DataCreator() { super(); } public DataCreator(List<Object> dataList, String[] array, int maxNum) { super(); this.dataList = dataList; this.array = array; this.maxNum = maxNum; } public String[] getArray() { return array; } public void setArray(String[] array) { this.array = array; } public List<Object> getDataList() { return dataList; } public void setDataList(List<Object> dataList) { this.dataList = dataList; } public int getMaxNum() { return maxNum; } public void setMaxNum(int maxNum) { this.maxNum = maxNum; } @Override public String toString() { StringBuffer buffer = new StringBuffer(); buffer.append("dataList:"+dataList.toArray(new Object[0])+","); buffer.append("array:"+Arrays.toString(array)+","); buffer.append("maxNum:"+maxNum); return buffer.toString(); } }

4.测试类(应用Timer进行循环测试)：

package com.suyun.cache; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.Date; import java.util.List; import java.util.Timer; import java.util.TimerTask; import com.suyun.model.Author; import com.suyun.model.Book; public class CreatorTest { private DataCreator creator; public DataCreator getCreator() { return creator; } public void setCreator(DataCreator creator) { this.creator = creator; } public void createData(){ List<Object> dataList = new ArrayList<Object>(); dataList.add("fsjkdjkfskfjksjkf"); Author author = new Author("Tiantian",33,"man","ShenZhen"); dataList.add(new Book("Book",author)); dataList.add(author); String[]array = {"This is a test...","Hello"}; int maxNum = Integer.MAX_VALUE; this.creator = new DataCreator(dataList,array,maxNum); } public static void main(String[] args) { Timer timer = new Timer(); final CreatorTest test = new CreatorTest(); test.createData(); final CacheOpration opration = CacheOpration.getInstance(); //opration.addCacheData("dataCreator", test.getCreator()); timer.schedule(new TimerTask(){ @Override public void run() { Object obj = opration.getCacheData(test, "getCreator", new Object[]{}, 10000, 10); System.out.println(obj); } }, new Date(), 1000); /** try { Method method = test.getClass().getMethod("getCreator", new Class[]{}); Object obj = method.invoke(test, new Object[]{}); System.out.println(obj); } catch (Exception e) { e.printStackTrace(); } **/ } }