java 兩種緩存

JAVA緩存有兩種: 

一、檔案緩存,是指把資料存儲在磁盤上，可以XML格式，也可以序列化檔案DAT格式還是其它檔案格式。 

二、記憶體緩存，也就是實作一個類中靜态Map,對這個Map進行正常的增删查。

其代碼如下：

目錄 [隐藏] 

1 Cache類 

2 CacheManager類 

 JAVA緩存-Cache類        

public class Cache { 

private String key;//緩存ID 

private Object value;//緩存資料 

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("删除前的大小："+CacheManager.getCacheSize()); 

// CacheManager.getCacheAllkey(); 

// CacheManager.clearAll("aaaa"); 

// System.out.println("删除後的大小："+CacheManager.getCacheSize()); 

}

JAVA緩存-CacheManager類        public class CacheManager { 

private static HashMap cacheMap = new HashMap(); 

//單執行個體構造方法 

private CacheManager() { 

//擷取布爾值的緩存 

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; 

//設定布爾值的緩存 

public synchronized static boolean setSimpleFlag(String key,boolean flag){ 

if (flag && getSimpleFlag(key)) {//假如為真不允許被覆寫 

}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); 

//得到緩存。同步靜态方法 

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,通過周遊HASHMAP下的所有對象，來判斷它的KEY與傳入的TYPE是否比對 

public synchronized static void clearAll(String type) { 

Iterator i = cacheMap.entrySet().iterator(); 

String key; 

ArrayList arr = new ArrayList(); 

while (i.hasNext()) { 

java.util.Map.Entry entry = (java.util.Map.Entry) i.next(); 

key = (String) entry.getKey(); 

if (key.startsWith(type)) { //如果比對則删除掉 

arr.add(key); 

for (int k = 0; k < arr.size(); k++) { 

clearOnly(arr.get(k)); 

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); 

//擷取緩存資訊 

public static Cache getCacheInfo(String key) { 

if (hasCache(key)) { 

Cache cache = getCache(key); 

if (cacheExpired(cache)) { //調用判斷是否終止方法 

cache.setExpired(true); 

return cache; 

}else 

return null; 

//載入緩存資訊 

public static void putCacheInfo(String key, Cache obj, long dt,boolean expired) { 

Cache cache = new Cache(); 

cache.setKey(key); 

cache.setTimeOut(dt + System.currentTimeMillis()); //設定多久後更新緩存 

cache.setValue(obj); 

cache.setExpired(expired); //緩存預設載入時，終止狀态為FALSE 

cacheMap.put(key, cache); 

//重寫載入緩存資訊方法 

public static void putCacheInfo(String key,Cache obj,long dt){ 

cache.setTimeOut(dt+System.currentTimeMillis()); 

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 

long nowDt = System.currentTimeMillis(); //系統目前的毫秒數 

long cacheDt = cache.getTimeOut(); //緩存内的過期毫秒數 

if (cacheDt <= 0||cacheDt>nowDt) { //過期時間小于等于零時,或者過期時間大于目前時間時，則為FALSE 

} else { //大于過期時間 即過期 

//擷取緩存中的大小 

public static int getCacheSize() { 

return cacheMap.size(); 

//擷取指定的類型的大小 

public static int getCacheSize(String type) { 

int k = 0; 

if (key.indexOf(type) != -1) { //如果比對則删除掉 

k++; 

return k; 

//擷取緩存對象中的所有鍵值名稱 

public static ArrayList getCacheAllkey() { 

ArrayList a = new ArrayList(); 

a.add((String) entry.getKey()); 

} catch (Exception ex) {} finally { 

return a; 

//擷取緩存對象中指定類型 的鍵值名稱 

public static ArrayList getCacheListkey(String type) { 

if (key.indexOf(type) != -1) { 

a.add(key);