import java.util.*;  //Description: 管理緩存  //可擴展的功能：當(dāng)chche到內(nèi)存溢出時必須清除掉最早期的一些緩存對象，這就要求對每個緩存對象保存創(chuàng)建時間 public class CacheManager {  private static HashMap cacheMap = new HashMap();  //單實例構(gòu)造方法  private CacheManager() {   super();  }  //獲取布爾值的緩存  public static boolean getSimpleFlag(String key){   try{    return (Boolean) cacheMap.get(key);   }catch(NullPointerException e){    return false;   }  }  public static long getServerStartdt(String key){   try {    return (Long)cacheMap.get(key);   } catch (Exception ex) {    return 0;   }  }  //設(shè)置布爾值的緩存  public synchronized static boolean setSimpleFlag(String key,boolean flag){   if (flag && getSimpleFlag(key)) {//假如為真不允許被覆蓋    return false;   }else{    cacheMap.put(key, flag);    return true;   }  }  public synchronized static boolean setSimpleFlag(String key,long serverbegrundt){   if (cacheMap.get(key) == null) {    cacheMap.put(key,serverbegrundt);    return true;   }else{    return false;   }  }  //得到緩存。同步靜態(tài)方法  private synchronized static Cache getCache(String key) {   return (Cache) cacheMap.get(key);  }  //判斷是否存在一個緩存  private synchronized static boolean hasCache(String key) {   return cacheMap.containsKey(key);  }  //清除所有緩存  public synchronized static void clearAll() {   cacheMap.clear();  }  //清除某一類特定緩存,通過遍歷HASHMAP下的所有對象，來判斷它的KEY與傳入的TYPE是否匹配  public synchronized static void clearAll(String type) {   Iterator i = cacheMap.entrySet().iterator();   String key;   ArrayList arr = new ArrayList();   try {    while (i.hasNext()) {     java.util.Map.Entry entry = (java.util.Map.Entry) i.next();     key = (String) entry.getKey();     if (key.startsWith(type)) { //如果匹配則刪除掉      arr.add(key);     }    }    for (int k = 0; k < arr.size(); k++) {     clearOnly(arr.get(k));    }   } catch (Exception ex) {    ex.printStackTrace();   }  }  //清除指定的緩存  public synchronized static void clearOnly(String key) {   cacheMap.remove(key);  }  //載入緩存  public synchronized static void putCache(String key, Cache obj) {   cacheMap.put(key, obj);  }  //獲取緩存信息  public static Cache getCacheInfo(String key) {   if (hasCache(key)) {    Cache cache = getCache(key);    if (cacheExpired(cache)) { //調(diào)用判斷是否終止方法     cache.setExpired(true);    }    return cache;   }else    return null;  }  //載入緩存信息  public static void putCacheInfo(String key, Cache obj, long dt,boolean expired) {   Cache cache = new Cache();   cache.setKey(key);   cache.setTimeOut(dt + System.currentTimeMillis()); //設(shè)置多久后更新緩存   cache.setValue(obj);   cache.setExpired(expired); //緩存默認(rèn)載入時，終止?fàn)顟B(tài)為FALSE   cacheMap.put(key, cache);  }  //重寫載入緩存信息方法  public static void putCacheInfo(String key,Cache obj,long dt){   Cache cache = new Cache();   cache.setKey(key);   cache.setTimeOut(dt+System.currentTimeMillis());   cache.setValue(obj);   cache.setExpired(false);   cacheMap.put(key,cache);  }  //判斷緩存是否終止  public static boolean cacheExpired(Cache cache) {   if (null == cache) { //傳入的緩存不存在    return false;   }   long nowDt = System.currentTimeMillis(); //系統(tǒng)當(dāng)前的毫秒數(shù)   long cacheDt = cache.getTimeOut(); //緩存內(nèi)的過期毫秒數(shù)   if (cacheDt <= 0||cacheDt>nowDt) { //過期時間小于等于零時,或者過期時間大于當(dāng)前時間時，則為FALSE    return false;   } else { //大于過期時間 即過期    return true;   }  }  //獲取緩存中的大小  public static int getCacheSize() {   return cacheMap.size();  }  //獲取指定的類型的大小  public static int getCacheSize(String type) {   int k = 0;   Iterator i = cacheMap.entrySet().iterator();   String key;   try {    while (i.hasNext()) {     java.util.Map.Entry entry = (java.util.Map.Entry) i.next();     key = (String) entry.getKey();     if (key.indexOf(type) != -1) { //如果匹配則刪除掉      k++;     }    }   } catch (Exception ex) {    ex.printStackTrace();   }   return k;  }  //獲取緩存對象中的所有鍵值名稱  public static ArrayList getCacheAllkey() {   ArrayList a = new ArrayList();   try {    Iterator i = cacheMap.entrySet().iterator();    while (i.hasNext()) {     java.util.Map.Entry entry = (java.util.Map.Entry) i.next();     a.add((String) entry.getKey());    }   } catch (Exception ex) {} finally {    return a;   }  }  //獲取緩存對象中指定類型 的鍵值名稱  public static ArrayList getCacheListkey(String type) {   ArrayList a = new ArrayList();   String key;   try {    Iterator i = cacheMap.entrySet().iterator();    while (i.hasNext()) {     java.util.Map.Entry entry = (java.util.Map.Entry) i.next();     key = (String) entry.getKey();     if (key.indexOf(type) != -1) {      a.add(key);     }    }   } catch (Exception ex) {} finally {    return a;   }  } } package lhm.hcy.guge.frameset.cache; public class Cache {   private String key;//緩存ID   private Object value;//緩存數(shù)據(jù)   private long timeOut;//更新時間   private boolean expired; //是否終止   public Cache() {     super();   }   public Cache(String key, Object value, long timeOut, boolean expired) {     this.key = key;     this.value = value;     this.timeOut = timeOut;     this.expired = expired;   }   public String getKey() {     return key;   }   public long getTimeOut() {     return timeOut;   }   public Object getValue() {     return value;   }   public void setKey(String string) {     key = string;   }   public void setTimeOut(long l) {     timeOut = l;   }   public void setValue(Object object) {     value = object;   }   public boolean isExpired() {     return expired;   }   public void setExpired(boolean b) {     expired = b;   } } //測試類， class Test {  public static void main(String[] args) {   System.out.println(CacheManager.getSimpleFlag("alksd")); //  CacheManager.putCache("abc", new Cache()); //  CacheManager.putCache("def", new Cache()); //  CacheManager.putCache("ccc", new Cache()); //  CacheManager.clearOnly(""); //  Cache c = new Cache(); //  for (int i = 0; i < 10; i++) { //   CacheManager.putCache("" + i, c); //  } //  CacheManager.putCache("aaaaaaaa", c); //  CacheManager.putCache("abchcy;alskd", c); //  CacheManager.putCache("cccccccc", c); //  CacheManager.putCache("abcoqiwhcy", c); //  System.out.println("刪除前的大?。?+CacheManager.getCacheSize()); //  CacheManager.getCacheAllkey(); //  CacheManager.clearAll("aaaa"); //  System.out.println("刪除后的大?。?+CacheManager.getCacheSize()); //  CacheManager.getCacheAllkey();  } }