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();}@Overridepublic 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;}@Overridepublic 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;}@Overridepublic 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(){@Overridepublic 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();}**/}}