-
package lhm.hcy.guge.frameset.cache;
import java.util.*;
/**
* <p>Title: </p>
*
* <p>Description: Manage cache</p>
* Deep blue 2008-11-28 think
* Extensible function: When chche reaches memory overflow, some of the earliest cache objects must be cleared, which requires saving the creation time of each cache object.
* <p>Copyright: Copyright (c) 2008</p>
*
* <p>Company: </p>
*
* @author Deepblue 2008-11-11
* @version 1.0
*/
public class CacheManager {
private static HashMap cacheMap = new HashMap();
//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 of Boolean values
public synchronized static boolean setSimpleFlag(String key,boolean flag){
if (flag && getSimpleFlag(key)) {//If true, overwriting is not allowed
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;
}
}
//Get the cache. Synchronized static methods
private synchronized static Cache getCache(String key) {
return (Cache) cacheMap.get(key);
}
//Determine whether there is a cache
private synchronized static boolean hasCache(String key) {
return cacheMap.containsKey(key);
}
//Clear all caches
public synchronized static void clearAll() {
cacheMap.clear();
}
//Clear a specific type of cache and determine whether its KEY matches the incoming TYPE by traversing all objects under the HASHMAP
public synchronized static void clearAll(String type) {
Iterator i = cacheMap.entrySet().iterator();
String key;
ArrayList<String> arr = new ArrayList<String>();
try {
while (i.hasNext()) {
java.util.Map.Entry entry = (java.util.Map.Entry) i.next();
key = (String) entry.getKey();
if (key.startsWith(type)) { //If matched, delete
arr.add(key);
}
}
for (int k = 0; k < arr.size(); k++) {
clearOnly(arr.get(k));
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
//Clear 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 static Cache getCacheInfo(String key) {
if (hasCache(key)) {
Cache cache = getCache(key);
if (cacheExpired(cache)) { //Call the method to determine whether to terminate
cache.setExpired(true);
}
return cache;
}else
return null;
}
//Load cache information
public static void putCacheInfo(String key, Cache obj, long dt,boolean expired) {
Cache cache = new Cache();
cache.setKey(key);
cache.setTimeOut(dt + System.currentTimeMillis()); //Set how long it takes to update the cache
cache.setValue(obj);
cache.setExpired(expired); //When the cache is loaded by default, the termination status is FALSE
cacheMap.put(key, cache);
}
//Rewrite the method of loading cache information
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);
}
//Determine whether the cache is terminated
public static boolean cacheExpired(Cache cache) {
if (null == cache) { //The incoming cache does not exist
return false;
}
long nowDt = System.currentTimeMillis(); //The current number of milliseconds in the system
long cacheDt = cache.getTimeOut(); //Expiration milliseconds in cache
if (cacheDt <= 0||cacheDt>nowDt) { //When the expiration time is less than or equal to zero, or when the expiration time is greater than the current time, it is FALSE
return false;
} else { //Expires if it is greater than the expiration time
return true;
}
}
//Get the size in cache
public static int getCacheSize() {
return cacheMap.size();
}
//Get the size of the specified type
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) { //If it matches, delete it
k++;
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
return k;
}
//Get all key value names in the cache object
public static ArrayList<String> 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;
}
}
//Get the key value name of the specified type in the cache object
public static ArrayList<String> 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;
/**
* <p>Title: </p>
*
* <p>Description: Cache DTO</p>
*
* <p>Copyright: Copyright (c) 2008</p>
*
* <p>Company: </p>
*
* @author Deepblue 2008-11-11
* @version 1.0
*/
public class Cache {
private String key;//cache ID
private Object value; // cache data
private long timeOut;//update time
private boolean expired; //whether to terminate
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;
}
}
//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 < 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("Size before deletion: "+CacheManager.getCacheSize());
// CacheManager.getCacheAllkey();
// CacheManager.clearAll("aaaa");
// System.out.println("Size after deletion: "+CacheManager.getCacheSize());
// CacheManager.getCacheAllkey();
}
}
This article comes from the CSDN blog. Please indicate the source when reprinting: http://blog.csdn.net/hello_zhenyu/archive/2009/12/18/5030366.aspx