Implementation of cache caching mechanism used in Java

    缓存，就是将程序或系统经常要调用的对象存在内存中，一遍其使用时可以快速调用，不必再去创建新的重复的实例。这样做可以减少系统开销，提高系统效率。    缓存主要可分为二大类:    一、通过文件缓存,顾名思义文件缓存是指把数据存储在磁盘上，不管你是以XML格式，序列化文件DAT格式还是其它文件格式；     

Importjava.util.*;//description: Managing caching //extensible functionality: when chche to memory overflow, you must erase some of the earliest cache objects, which requires that you save the creation time for each cached object public  class CacheManager {     Private StaticHashMap Cachemap =NewHashMap ();//single Instance Construction method    Private CacheManager() {Super(); }//get the cache of Boolean values     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; }     }//set the cache for Boolean values     public synchronized Static Boolean Setsimpleflag(String key,BooleanFlag) {if(flag && Getsimpleflag (key)) {//if It is not allowed to be overwritten            return false; }Else{cachemap.put (key, flag);return true; }     } public synchronized Static Boolean Setsimpleflag(String key,LongServerbegrundt) {if(cachemap.get (key) = =NULL) {cachemap.put (key,serverbegrundt);return true; }Else{return false; }     }//get Cached. Synchronous static Methods    Private synchronized StaticCacheGetCache(String Key) {return(Cache) Cachemap.get (key); }//determine If a cache exists    Private synchronized Static Boolean Hascache(String Key) {returnCachemap.containskey (key); }//clear All caches     public synchronized Static void ClearAll() {cachemap.clear (); }//clears A particular type of cache by traversing all objects under HashMap to determine if its key matches the incoming type     public synchronized Static void ClearAll(String Type)         {Iterator i = cachemap.entryset (). Iterator ();         String key; ArrayList arr =NewArrayList ();Try{ while(i.hasnext ())                 {java.util.Map.Entry Entry = (java.util.Map.Entry) I.next (); Key = (String) Entry.getkey ();if(key.startswith (type)) {//if the match is droppedArr.add (key); }             } for(intK =0; K < Arr.size ();             K++) {clearonly (arr.get (k)); }         }Catch(Exception Ex)         {ex.printstacktrace (); }     }//clears the specified cache     public synchronized Static void clearonly(String Key)     {cachemap.remove (key); }//load Cache     public synchronized Static void Putcache(String key, Cache Obj)     {cachemap.put (key, obj); }//get Cache Information     public StaticCacheGetcacheinfo(String Key) {if(hascache (key)) {cache cache = GetCache (key);if(cacheexpired (cache)) {//call to determine whether to terminate the methodCache.setexpired (true); }returnCache }Else             return NULL; }//load Cache Information     public Static void Putcacheinfo(String key, Cache obj,LongDtBooleanExpired) {cache cache =NewCache ();         Cache.setkey (key); Cache.settimeout (dt + system.currenttimemillis ());//set How long after the cache is updatedCache.setvalue (obj); Cache.setexpired (expired);//cache is loaded by default and the termination status is FalseCachemap.put (key, cache); }//override Load Cache information Method     public Static void Putcacheinfo(String Key,cache obj,LongDt) {cache cache =NewCache ();         Cache.setkey (key);         Cache.settimeout (dt+system.currenttimemillis ());         Cache.setvalue (obj); Cache.setexpired (false);     Cachemap.put (key,cache); }//determine If the cache is terminated     public Static Boolean cacheexpired(cache Cache) {if(NULL= = Cache) {//the incoming cache does not exist            return false; }LongNOWDT = System.currenttimemillis ();//system Current number of milliseconds        LongCachedt = Cache.gettimeout ();//number of expired milliseconds in cache        if(cachedt <=0|| Cachedt>nowdt) {//the expiration time is less than or equal to zero, or false if the expiration time is greater than the current time            return false; }Else{//greater than expiration time expires            return true; }     }//get the size in the cache     public Static int getcachesize() {returnCachemap.size (); }//gets the size of the specified type     public Static int getcachesize(String Type) {intK =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) {//if the match is droppedk++; }             }         }Catch(Exception Ex)         {ex.printstacktrace (); }returnK }//get all Key-value names in the cache object     public StaticArrayListGetcacheallkey() {ArrayList A =NewArrayList ();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{returnA }     }//gets The key value name of the specified type in the cache object     public StaticArrayListGetcachelistkey(String Type) {ArrayList A =NewArrayList (); 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{returnA }     } } packagelhm.hcy.guge.frameset.cache; public  class Cache {         PrivateString key;//cache ID        PrivateObject value;//cache Data        Private LongtimeOut;//update Time        Private BooleanExpired//whether Termination         public Cache() {Super(); } public Cache(String key, Object value,LongtimeOut,BooleanExpired) { this. Key = key; this. Value = value; this. Timeout = timeout; this. expired = expired; } publicStringGetKey() {returnKey } public Long GetTimeout() {returntimeOut; } publicObjectGetValue() {returnValue } public void Setkey(string String)         {key = string; } public void SetTimeOut(LongL) {timeOut = l; } public void SetValue(object Object)         {value = object; } public Boolean isexpired() {returnExpired } public void setexpired(BooleanB) {expired = b; } }//test class,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 < 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 ("size before deletion:" +cachemanager.getcachesize ());//cachemanager.getcacheallkey ();//cachemanager.clearall ("aaaa");//System.out.println ("size after deletion:" +cachemanager.getcachesize ());//cachemanager.getcacheallkey ();} }

Implementation of cache caching mechanism used in Java